The IQ Controversy, the Media and Public Policy 0887388396, 9780887388392

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The IQ Controversy, the Media and Public Policy Mark Snyderman and Stanley Rothman

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Transaction Books N ew B runsw ick (U SA ) and O xford (UK )

C opy rig h t © 1988 by T ra n sactio n , Inc. N ew B runsw ick, N ew Jersey 08903 All rights reserved u n d e r In te rn a tio n a l a n d P an -A m erica n C o p y rig h t C o n ­ v entions. N o p a rt o f th is b o o k m ay be re p ro d u ce d o r tra n sm itte d in an y fo rm o r by an y m eans, elec tro n ic o r m e ch an ical, in c lu d in g photocopy, recording, o r an y in fo rm a tio n storage an d retrieval system , w ith o u t p rio r p erm issio n in w riting from th e publisher. All in q u irie s sh o u ld be ad d ressed to T ra n sactio n Books, R u tg ers— T h e S tate U niversity, N ew B runsw ick, N ew Jersey 08903. L ib rary o f C ongress C atalog N u m b er: 87-35403 ISBN: 0-88738-151-0 P rin ted in th e U n ite d S tates o f A m erica Library o f C ongress Cataloging in Publication Data S n y d e rm a n , M ark. T h e controversy, th e m edia, a n d p u b lic policy / M ark S n y d e rm a n an d S tanley R o th m a n . p. cm . ISB N 0-88738-151-0 1. Intelligence levels. 2. Intelligence levels in m ass m ed ia. 3. Intelligence levels— P ublic o p in io n . 4. Intelligence levels-G o v e rn m e n t policy. I. R o th m a n , Stanley, 1927. II. T itle. III. T itle: Intelligence q u o tie n t controversy, th e m ed ia, a n d p u b lic policy. BF431.S615 1988 153.9'dc 19 87-35403

To m y p a re n ts for all they have given. — M.S. To D .R .T. for helping m e u n d ersta n d . — S.R.

Contents P reface A ck now ledgm ents 1. In tro d u c tio n : T h e IQ C ontroversy in P erspective 2. T h e N a tu re o f Intelligence 3. T h e H erita b ility o f IQ 4. R ace an d Class D ifferences in IQ 5. T h e Im p ac t o f Intelligence T esting 6. It's All T h ere in Black an d W hite: T h e E x ten t o f N ew s M edia C overage 7. N o N ew s Is G o o d News: T he N a tu re o f N ew s M edia C overage 8. C onclusion: T h e N ew Sociology o f Science A p p endices Index

ix x iii 1 43 79 105 139 175 203 249 261 303

Preface Very few q u estio n s have spark ed m o re vio len t co n tro v ersy in th e past tw o decades th a n tho se relatin g to th e n a tu re o f in telligence an d in te l­ ligence testing. In th e 1950s it w as w idely agreed by b o th ex p e rts a n d th e in fo rm ed pu b lic th a t intelligence was so m e th in g th a t co u ld be m e asu red by IQ tests, an d th a t b o th th e genetic en d o w m e n t o f th e in d iv id u al a n d his o r her e n v iro n m e n t played a role in differences in m e asu red intelligence. D u rin g th e 1960s an d 1970s th is view ca m e u n d e r sh a rp attack . IQ tests w ere c o n d e m n e d as biased against b oth m in o ritie s a n d th e poor. It was asserted th a t we d o n o t know w h at intelligence is; th a t w h atev er it is, we do n o t know how to m easu re it, a n d th a t in d iv id u al differences in intelligence, how ever m easu red , are prim arily, if n o t entirely, a fu n ctio n o f n u rtu re ra th e r th a n genetic en d o w m e n t. Today th e critiq u es o f IQ an d intelligence testin g have achieved th e statu s o f co n v e n tio n a l w isdom a m o n g ed u c ated laym en. It is w idely believed th a t new er scientific stu d ies have discred ited old er views, w hich w ere b ased on b ad , even d ish o n est, science, a n d th a t th e great m a jo rity o f scien tists in the field o f intelligence a n d intelligence studies su p p o rt th ese studies. T h e new co n v e n tio n a l w isdom has had im p o rta n t p u b lic policy co n seq u en ces. To d e te rm in e th e views o f th e relev an t scientific c o m m u n ity o n these m a tte rs, we surveyed a b ro ad sam ple o f (p rim arily acad em ic) ex p e rts in th e field. We fo u n d th a t, w hatever th e co n v e n tio n a l w isdom holds, m o st ex ­ p erts c o n tin u e to believe th a t intelligence can be m easu red , a n d th a t ge­ n etic en d o w m e n t plays an im p o rta n t role in in d iv id u al differences in IQ. W hile ex p erts believe th a t IQ tests are so m ew h at biased, th ey do n o t b e­ lieve th a t th e bias is serious en o u g h to d iscred it such tests, an d th ey believe th a t m easu red IQ is an im p o rta n t d e te rm in a n t o f success in A m erican society. Indeed, despite th e discred itin g o f so m e o f Cyril B u rt’s w ork on IQ heritability, th e w eight o f evidence su p p o rtin g such views, to ju d g e from th e scholarly literatu re , is p ro b ab ly g reater today th a n it was in th e 1950s. In th is book we are less in terested in w h eth e r o r n o t th e ex p erts are right th a n in exploring th e reaso n s for th e divergence o f ex p e rt an d p u b lic views an d th e influence o f this divergence on pu b lic policy. T h e IQ co n tro v ersy is

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The IQ Controversy

ex a m in e d in th e c o n te x t o f o u r study o f ex p e rt o p in io n . E x p ert o p in io n is th e n c o m p a re d to new s m e d ia re p o rtin g o f su ch o p in io n , based o n a d e­ ta ile d c o n te n t analysis o f coverage o f th e IQ co n tro v ersy by th e n atio n al m e d ia over a p erio d o f fifteen years. We co n c lu d e th a t th e p u b lic ’s view o f th e IQ co n tro v ersy has been p artly sh ap ed by in a c c u ra te m ed ia coverage, b u t th a t, m o re broadly, it has been sh ap ed by changes in th e n a tu re o f A m eric an liberalism a n d th e key ro le o f th e civil rights issue in A m eric an life. T h e a rtic u la te p u b lic ’s p erc ep tio n s o f th e o p in io n s o f ex p e rts in th e field have b een sh ap ed far m o re by th e g eneral in tellectu al c lim a te th a n by th e ac tu a l views o f th e ex p e rt c o m ­ m unity. T h is b o o k consists o f eight chapters. C h a p te r 1 discusses th e h isto ry o f th e study o f IQ a n d p u b lic contro v ersy a b o u t it. O u r survey o f ex p e rt o p in io n is in tro d u c e d in C h a p te r 2. C h a p te rs 2 to 5 su m m a riz e th e contro v ersy over th e n a tu re o f in te l­ ligence, th e q u e stio n o f heritability, g ro u p differences in IQ , a n d th e use o f intelligence tests. T h e scholarly a n d lay lite ra tu re on th ese issues is re­ view ed an d th e views o f o u r ex p e rt sam p le discussed. (A so m ew h at m o re tech n ical, if briefer, discussion o f th e resu lts o f o u r survey can be fo u n d in M ark S n y d e rm a n an d S tanley R o th m a n , “ Survey o f E x p ert O p in io n on Intelligence a n d A p titu d e T esting,” A m eric a n P sychologist 42, 2 (F e b ru a ry 1987): 137—144.) C h a p te rs 6 a n d 7 describe o u r analysis o f new s m e d ia coverage o f th e IQ issue. O u r findings are su m m a riz e d in C h a p te r 8. In th a t ch a p te r we also r e tu rn to th e ce n tral th e m e o f th e study, i.e., th e social a n d p o litical facto rs th a t influence th e c o m m u n ic a tio n o f in fo rm a tio n a b o u t co n tro v ersial sci­ entific issues to th e p ublic. We also draw so m e g en eral co n c lu sio n s a b o u t th e ch an g in g role o f science a n d scientists in decisio n s a b o u t p u b lic policy. We c o n c lu d e th a t th e grow ing in fluence o f new strateg ic elites a n d th e ch an g in g role o f th e m ass m e d ia have had a p ro fo u n d effect on th e c o m ­ m u n ic a tio n o f scientific in fo rm a tio n to th e public. T h e en d o f th e book c o n ta in s a series o f a p p e n d ic es th a t g enerally c o n ­ ta in m o re tech n ical in fo rm a tio n a b o u t th e ex p e rt survey a n d c o n te n t a n a l­ ysis. A p p e n d ix A is a c h ro n o lo g y o f th e d e v e lo p m e n t o f n o tio n s o f intelligence a n d intelligence te stin g a n d th e con tro v ersy a b o u t these. A p ­ p en d ix E is o f p a rtic u la r n o te because it c o n ta in s th e resu lts o f a su rv ey o f th e a ttitu d e s o f jo u rn a lis ts an d ed ito rs o n th e IQ q u estio n . T h is book is o n e o f a series o f studies sp o n so red by th e C e n te r for th e S tu d y o f Social a n d P olitical C h an g e a t S m ith C ollege. T h e stu d ies focus on c o m m u n ic a tio n o f scientific in fo rm a tio n a b o u t co n tro v ersial issues to th e p ublic. O th e r areas th a t have been o r are being stu d ied in clu d e n u clea r

Preface

xi

energy an d en v iro n m e n ta l cancer. T hese studies, in tu r n , are p a rt o f a m a jo r ex p lo ra tio n by th e C e n te r o f the n a tu re a n d d irec tio n o f social an d p o litical change in th e U n ite d S tates, directed by S tanley R o th m a n . O u r q u estio n n a ire s, codebooks, an d c o m p u te r tap es have been d ep o si­ te d at th e R o p er P ublic O p in io n C e n te r at th e U n iv ersity o f C o n n e cticu t, as have the tap es a n d co d ebook o f o u r c o n te n t analysis.

Acknowledgements T h e a u th o rs gratefully acknow ledge th e follow ing scholars a n d p u b lic a ­ tio n s fo r p e rm issio n to use p re v io u sly p u b lis h e d m a te ria l: P ro fesso r T h o m a s J. B ouchard, Jr. an d S cience for p erm issio n to use F igure 1 from T.J. B o uchard et. al. “ F am ilia S tudies o f Intelligence: A R eview ” , S cience 212 (29 May. 1981), p.1056. We th a n k Ja m es D avis, S heldon W hite, a n d th e p ilo t stu d y resp o n d e n ts for th e ir helpful c o m m e n ts d u rin g th e d ev e lo p m e n t o f th e q u estio n n a ire , K ath lee n M c C artn e y a n d D ouw e Y n te m a for th e ir help w ith th e statistical analyses, an d Ja cq u e lin e B o u d reau an d A rian n e S tu b b s for th e ir assistance in th e p re p a ra tio n an d m ailing o f th e q u e stio n n a ire s a n d fo llo w -u p s. A lan M cA rdle played a key role in getting th e d a ta in final o rd e r a n d in d ev elo p ­ ing th e m ore com p lex statistical analyses. K u d o s to Ia n C o n d ry , S ally C o n n o r, M ic h a e l E a s tw o o d , A im e e F lam ilto n , R ich ard M alone, a n d Ja n e W ein zim m er for w ith stan d in g th e ord eal o f c o n te n t analysis coding. O le H olsti a n d Phil S to n e lent th e ir ex p ertise to th e d ev e lo p m e n t o f th e coding schem e. P atric ia D avies helped th e c o n te n t analysis ch a p te rs alo n g th e p ath to readability. T h e en tire p ro ­ je c t w as aided by several co n v e rsatio n s w ith C arol Weiss. Special th a n k s to R ich a rd H e rrn ste in for his in v alu ab le co m m e n ts on th e q u e stio n n a ire a n d th e m a n u sc rip t o f th e b ook , as well as for access to his v o lu m in o u s files, an d to W ill G o ld b eck , w ho deserves m u c h o f th e c red it for w h a t’s right w ith th e c o n te n t analysis, an d n o n e o f th e b lam e for w h a t’s w rong. T h e follow ing fo u n d a tio n s p rovided financial su p p o rt for o u r w ork: T h e C a rth ag e F o u n d a tio n , T he S arah Scaife F o u n d a tio n , T h e E a rh a rt F o u n d a ­ tio n , a n d T h e J. M. F o u n d a tio n .

1 Introduction: The IQ Controversy in Perspective

The C hallenge to Testing

In F eb ru ary 1969, th e H arvard E d u ca tio n a l R eview ( H E R ) p u b lish ed an artic le en title d “ H ow M uch C an We Boost IQ a n d S cholastic A chieve­ m e n t? ” T h e auth o r, U n iv ersity o f C a lifo rn ia ed u c a tio n professor A rth u r Je n sen , h ypothesized th a t th e a p p a re n t failure o f large scale co m p en sa to ry e d u c a tio n p ro g ra m s in te n d e d to b o o st IQ a n d sc h o lastic a c h ie v e m e n t co u ld be traced to th e largely h eritab le n a tu re o f intelligence. H e also p ro p o sed th a t th e average IQ difference betw een th e b lack an d w hite p o p u ­ la tio n s in th e U n ite d States m ight be d u e in p a rt to gen etic factors. R eactio n to J e n se n ’s article w as swift an d severe. T h e m essage scraw led o n w alls an d p lacard s an d c o n ta in e d in h an d b ills d istrib u te d by stu d e n t p ro testo rs at Berkeley was th a t Je n sen w as a racist an d a N azi, a n d sh o u ld be o u sted from th e university. Je n se n ’s office w as p icketed, a n d his classes w ere regularly d isru p te d . S im ilar rea ctio n m e t Je n s e n ’s a tte m p ts to give lectures at o th e r cam puses. For weeks, th e stu d e n t n ew sp ap er was filled w ith articles an d letters c o n c e rn in g Je n sen , m o st highly critical, m a n y violently so. A t o n e p o in t, th e activities o f th e Berkeley ch a p te r o f th e S tu d en ts for a D em o c ratic Society (SD S) b ecam e so bellig eren t th a t th e c a m p u s police th o u g h t it best to assign tw o p la in clo th es b o d y g u ard s to ac c o m p an y Je n sen a ro u n d c a m p u s.1 A t H arv ard , letters to th e C rim so n also a tta c k e d Jen sen , b u t m an y p ro ­ tests w ere directed at th e H E R for having p u b lish ed th e article. P erh ap s a n tic ip a tin g th e in fla m m a to ry effect o f Je n se n ’s arg u m e n ts, th e H E R had solicited, p rio r to th e p u b lic atio n o f Jen sen 's article, c o m m e n ta rie s by seven ex p e rt critics. T hese w ere p ublished in th e follow ing issue (Spring). But even the ed ito rs o f th e H E R h ad n o t an tic ip a te d th e full force o f th e

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The IQ Controversy

rea ctio n to Je n sen , an d they w ere u n p re p a re d to h an d le it. D ecid in g th a t th e seven scholarly reb u ttals p u blished in th e sp rin g w ere insufficient, th e ed ito rs in clu d ed a d d itio n a l critiq u es in th e S u m m e r 1969 issue o f th e jo u r ­ nal. M any o f these, by th e ir u ncivil a n d a rb itra ry n atu re , w ere far below th e sta n d a rd s o f an acad em ic jo u rn a l. T he ed ito rs released a sta te m e n t c la im ­ ing th a t they h ad nev er asked Je n sen to deal w ith th e racial issue in his article, an assertio n Je n sen w as easily able to refu te by p ro d u c in g a copy o f H E R 's original so licitatio n le tte r in c lu d in g an o u tlin e specifically m e n tio n ­ ing racial differences in intelligence. W hen all else failed, th e H E R ed ito rs te m p o ra rily sto p p ed selling copies o f th e issue co n ta in in g Je n se n ’s article, even refusing to sell rep rin ts to Jen sen him self.2 R e a c tio n fro m J e n s e n ’s p ro fe ssio n a l colleag u es w as, a t best, m ix ed . M an y d ecried th e uncivil tre a tm e n t being acco rd ed Je n sen , an d p u b licly d efen d ed his right to express his views, w hile d eclarin g th e ir ow n disag ree­ m e n t w ith his conclu sio n s. O th ers expressed th e ir a g re em e n t w ith Je n sen in perso n al letters a n d co n v ersatio n s, b u t w ere u nw illing to d o so publicly. T h e strongest a n d m o st p ro m in e n t professional sta te m e n ts w ere d ecid ed ly a n ti- J e n s e n .3 T h e S ociety fo r th e P sychological S tu d y o f S ocial Issues (SPSSI), a d ivision o f th e A m eric an Psychological A sso ciatio n (APA), re­ leased a five page sta te m e n t to all the m a jo r new s services o u tlin in g th e ir d isa g re em en t w ith v irtu ally all o f th e m a jo r p o in ts in Je n s e n ’s article .4 A g ro u p called Psychologists for Social A ction urged J e n s e n ’s ex p u lsio n from th e APA. T h e 1969 co n v e n tio n o f th e A m eric an A n th ro p o lo g ical A ssocia­ tio n (AA A ) passed a reso lu tio n co n d e m n in g J e n se n ’s p o sitio n on racial differences a n d en c o u rag in g m em b ers to fight racism th ro u g h th e use o f “ all available o u tle ts in th e n a tio n a l a n d local m ed ia.”5 T h e u p ro a r su rro u n d in g J e n se n ’s thesis w as n o t lim ite d to college c a m ­ puses. As th e AAA h ad h o ped, th e n a tio n a l a n d local new s m ed ia w ere q u ic k to pick u p on th e story, em p h asizin g J e n s e n ’s co n c lu sio n s a b o u t racial differences. T h e H E R ed ito rs them selves played a cru cial ro le in fostering press coverage, se n d in g press releases a n d co p ies o f th e a rtic le an d reb u ttals to m a n y new spapers an d p o p u la r m agazines. T h e m e d ia w asted n o tim e in giving full coverage to Jen sen . By J u n e 1969, th e N e w York T im e s alread y h ad d ev o ted several articles to Je n se n ’s a rg u m e n ts a n d th e en su in g p rotests, an d each o f th e th ree m a jo r new sw eeklies h ad p u b lish ed at least o n e artic le on Je n se n ’s th e o ry th a t blacks are “ B o rn D u m b .”6 L ocal new spapers th ro u g h o u t th e c o u n try pro v id ed sim ila r coverage. W h en th e N e w York T im e s M a g a zin e p u b lish ed a lengthy article en title d “je n sen ism , n. T h e T h eo ry th a t IQ Is D e te rm in e d Largely by th e G en es” in A ugust 1969, n o t on ly h ad a new w ord e n tered th e m ed ia vocabulary, b u t th e T im e s M a g a zin e received m o re letters th a n it had for th e p u b lic a tio n o f an y artic le in its history, a n d m o re letters th a n th e p ap e r h ad received on

Introduction: The IQ Controversy in Perspective

3

an y issue since th e assassination o f P resid en t K ennedy.7 T h e T im es M a g a ­ zin e p u blished fifteen o f th e letters over a tw o -w eek p erio d . M an y o f th e m n o t only attac k ed Je n sen for his p o sitio n s on th e h eritab le n a tu re o f in te l­ ligence. an d th e possible genetic causes o f race differences in IQ. b u t also criticized intelligence tests in general as biased a n d m ean in g less as m e a ­ sures o f intelligence. The Controversy and Its Effects T h e c o n te n t o f th e T im e s M a g a zin e letters is an in d ic atio n th a t th e p u blic controversy h ad b ec o m e m u ch larger th a n Je n sen a n d his h y p o th ­ eses. T he past eighteen years has seen a steady stream o f attac k s on in te l­ ligence an d a p titu d e tests, b o th from p o litica l o rg a n iz a tio n s a n d from w ith in th e psychological an d ed u c atio n al c o m m u n itie s. It is freq u en tly claim ed th a t tests are cu ltu rally biased, invalid, irre le v an t, stig m atizin g , an d restrictive o f o p p o rtu n itie s. Test m ak ers have been accused o f ex ertin g u n w a rra n te d co n tro l over test ta k ers’ lives, an d o f engaging in secretive an d u n fair practices. O rg a n iz atio n s like th e N atio n al E d u ca tio n A ssociation (N EA ). th e N AACP. a n d th e A ssociation o f Black Psychologists (A B P) have called for a co m p lete m o ra to riu m on sta n d ard iz ed tests. R alp h N ad e r has been active in recen t years in criticizing th e E d u ca tio n a l T esting Service (ETS), m akers o f th e Scholastic A p titu d e Test (SAT) an d o th e r ad m issio n s tests, for p e rp e tu a tin g class d istin ctio n s, a n d th e ir ow n w ealth, th ro u g h biased a n d m eaningless tests. Books w ith titles like T h e S cien ce a n d P olitics o f IQ , T he T esting Trap, T he M y th o f M ea su ra b ility , an d T h e M ism e a su re o f M a n have added fuel to th e fire by q u e s tio n in g th e en tire testin g en te r­ p rise.8 N o r has th is criticism subsided. A n O cto b e r 1985 press co n feren ce a n n o u n c e d th e fo rm a tio n o f “ FairT est.” an o rg an iz atio n w hose p u rp o se it is to “e x a m in e th e exam iners.” Jo h n Weiss, th e executive d ire c to r o f F air­ T est e x p la in e d th a t “ [e]very y ea r th e e d u c a tio n a l a n d c a re e r o p p o r ­ tu n itie s— an d self p erc ep tio n s— o f over 10 m illio n A m eric an s are forever altered by p sychological exam s. M o st o f th e se sta n d a rd iz e d m u ltip le ch oice tests are cu ltu rally biased an d p oorly designed.”9 T h e result o f m u c h o f th is criticism has been su b stan tia l change in test use p ractices in th e th ree m a jo r areas in w hich in telligence an d ap titu d e tests have tra d itio n a lly been used: elem e n ta ry a n d se co n d a ry schools, e m ­ p lo y m en t. an d ad m issio n to schools o f higher e d u c atio n . As a m a tte r o f g eneral practice in e le m e n ta ry an d se co n d a ry schools, th e re is reason to believe th a t tests o f intelligence an d general a p titu d e are n o t as freq u en tly given, o r as often used, as they once were. In a 1964 n atio n w id e survey c o n d u c te d by th e A kro n , O hio, P ublic S chools, 100% o f large -c ity an d - c o u n ty test d irec to rs polled re p o rte d using g ro u p ab ility (intelligence a n d

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The IQ Controversy

a p titu d e ) tests in elem e n ta ry school grades 4 th ro u g h 6, a n d in ju n io r high g rades 7 th ro u g h 9. A 1977 fo llo w -u p survey fo u n d th a t th e freq u en cy o f test use had declin ed d ram atically, to 23.4% in g rades 4 to 6 a n d 35.1% in ju n io r high sc h o o l.10 M uch o f th e change in g ro u p intelligence a n d a p titu d e test use is a resu lt o f a grow ing ed u c atio n al tre n d away fro m th e se p aratio n o f stu d e n ts in to ab ility groups, know n as track in g . C onsequently, as even m a n y o f testing's strongest p ro p o n e n ts have agreed, w ith o u t th e necessity o f se p aratin g s tu ­ d e n ts by ability level m u c h o f th e need for sy stem atic in telligence an d a p titu d e testing vanishes. A fter all, how useful is know ledge o f a stu d e n t’s IQ to a te ac h er w hose p rim a ry c o n c e rn is th a t th e stu d e n t m a ste r th e class m a terial? T h ere is, o n th e o th e r h an d , th e d an g e r th a t th ese n u m b e rs (IQ an d a p titu d e test scores) ca n be m isin te rp rete d a n d m isu sed by th o se w ith ­ o u t th e p ro p e r train in g . S om e have expressed th e fear th a t know ledge o f in telligence test scores m ay actu ally be h a rm fu l to th e stu d e n t, creatin g u n rea listic ex p e ctatio n s o f e ith e r to o little o r to o g reat ac ad e m ic ach iev e­ m ent. T h e m o v e m en t away from track in g , a n d fro m th e use o f in telligence a n d a p titu d e tests in m a k in g trac k in g decisions, w as given a su b stan tia l b o o st by a 1967 federal c o u rt decision. H ob so n v. H a n se n 11 w as th e first in a series o f c o u rt cases involving testin g th a t have h a d a m a jo r im p a c t on testin g practices. In H obson, th e ability g ro u p in g system th e n in ex isten ce in th e W ashington, D .C ., p u b lic schools was ch allenged as b eing racially d isc rim i­ n a to ry as defined in T itle VI o f th e Civil R ights A ct o f 1964. T h e p rin cip al piece o f evidence for racial d isc rim in a tio n w as th e d isp ro p o rtio n a te e n ro ll­ m e n t o f black ch ild ren in low er ability groups. T esting b ec am e an issue in th e case because it was d e te rm in e d th a t scores o n g ro u p -a d m in is te re d ap titu d e tests w ere an im p o rta n t elem e n t in th e p la ce m en t decision. O n average, black stu d e n ts scored low er on these tests th a n d id w h ite stu d en ts. Ju d g e Skelly W right was th u s forced to e x a m in e th e valid ity o f th ese tests. E x p ert testim o n y from b o th sides o f th e case m a d e it clear th a t th e ap titu d e tests used w ere n o t, n o r w ere th ey in te n d e d as, m e asu res o f in n a te ability, b u t w ere in te n d e d as tests o f ac q u ired skills th a t are in flu en ced by a ch ild ’s c u ltu ra l a n d ed u c atio n al b ac k g ro u n d . To Ju d g e W right, th a t black ch ild ren scored low er o n such tests w as ta n ta m o u n t to racial bias, a n d he ru led in favor o f th e plaintiffs, striking dow n th e D .C . trac k in g system , a n d p lacing a stigm a on intelligence a n d a p titu d e tests. T h e o n u s o f th e H ob so n d ecision w as felt clearly in L a r r y P. v. W ilson R ile s ,12 th e m o st im p o r ta n t c o u r t case to d a te in v o lv in g IQ tests. In N o v em b e r 1971, th e p a re n ts o f seven b lack ch ild ren b ro u g h t su it ag ain st th e S tate o f C a lifo rn ia in th e U n ite d States D istric t C o u rt for th e N o rth e rn D istric t o f C a lifo rn ia, claim in g th a t th e ir ch ild ren h ad been in c o rrec tly

Introduction: The IQ Controversy in Perspective

5

p laced in classes for th e educab le m en tally reta rd e d (E M R ) o n th e basis o f cu ltu rally biased IQ tests. T h e plaintiffs, u n d e r th e in stig atio n an d w ith th e assistance o f th e Bay A rea A ssociation o f Black P sychologists, th e U rb a n League, an d th e N A A C P Legal D efense F u n d , a m o n g o th ers, p resen ted as ev idence o f racial d isc rim in a tio n th e fact th a t b lack ch ild ren w ere rep re­ sen ted in E M R classes in San F rancisco in n u m b e rs far in excess o f th e ir p ro p o rtio n in th e school d istric t as a w hole, as well as th e claim th a t th e ch allenged intelligence tests w ere th e p rim a ry d e te rm in a n t o f E M R p lace­ m en t. A n in ju n c tio n was sought, calling for th e e lim in a tio n o f all cu ltu rally b iased tests, a réé v alu a tio n o f all black E M R ch ild ren , a n d th e estab lish ­ m e n t o f a q u o ta so th a t black ch ild ren w ould no longer be d isp ro p o r­ tio n a te ly assigned to E M R classes. T h e case w as h eard by Ju d g e R o b e rt P eckham . T h ere is an im p o rta n t d istin c tio n betw een th e H o b so n an d L a rry P. cases, o th e r th a n th a t o nly th e la tte r w as a challenge to tests directly. H o b ­ son involved larg e -scale a d m in istra tio n o f gro u p in telligence a n d a p titu d e tests in an ap p lica tio n o f q u estio n a b le value, ability gro u p in g . In L a r r y P., o n th e o th e r h an d , in d iv id u ally a d m in iste re d intelligence tests, universally recognized as m o re valid a n d reliable th a n gro u p tests, w ere being attac k ed precisely w here they had previously been th o u g h t to be m o st useful, for d iagnosis o f a n d ed u c atio n al p la n n in g for special needs stu d en ts. Ju d g e P eckham accepted th e d a ta on d isp ro p o rtio n a te E M R e n ro llm e n t as p rim a facie evidence o f d isc rim in a tio n , th u s shifting th e b u rd e n o f p ro o f to th e d efe n d an ts to show a ratio n al c o n n e c tio n betw een th e tests an d th e ir alleged use. As a resu lt o f th e p re lim in a ry hearing. Ju d g e P eck h am c o n ­ clu d ed th a t the state had failed to m eet th is b u rd e n , an d ru led th a t th e school system had vio lated th e stu d e n ts' rights to eq u al p ro tec tio n . H e g ran te d a p re lim in a ry in ju n c tio n in 1972 en jo in in g an y fu tu re p la ce m en t o f black ch ild ren in to E M R classes on th e basis o f in telligence tests. In 1974, th a t in ju n c tio n was b ro ad e n ed to in c lu d e th e elim in a tio n o f in te l­ ligence testin g o f all black ch ild ren in C a lifo rn ia, an d a y ear later th e state b o ard o f ed u c a tio n ex ten d ed th e m o ra to riu m to th e use o f in telligence tests for th e p la ce m en t o f all stu d e n ts in to E M R classes. T h e full trial began in O cto b e r 1977 a n d lasted over seven m o n th s. T w enty-six ex p e rt w itnesses w ere called by b o th sides, in an a tte m p t to establish th e validity, o r invalidity, o f IQ tests for E M R p lacem en t. T h e c o u r t’s decision, w hich did n o t co m e u n til 1979, w as essentially th e sam e as in th e p re lim in a ry hearing. Judge P eckham fo u n d c u ltu ra l bias in tests to be th e m o st rea so n ab le e x p la n a tio n for th e d isp ro p o rtio n a te n u m b e r o f blacks in E M R classes, a n d co n c lu d e d th a t th e state had o n ce again failed to establish th e validity o f intelligence tests for th is pu rp o se. T h e ju d g e th e re fo re ru led th a t th e plaintiffs had m et th e ir b u rd e n o f proving d isc rim i­

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n a tio n on th e p a rt o f th e state, a n d en jo in ed th e sta te fro m using an y IQ tests fo r th e p la ce m en t o f b lack ch ild ren in to E M R classes w ith o u t th e p rio r ap proval o f th e c o u rt. In a d d itio n , th e c o u r t’s d ecisio n req u ired th a t th e sta tu s o f all b lack ch ild ren cu rre n tly en ro lled in E M R classes be im m e ­ d iately reev alu ated , an d th a t E M R e n ro llm e n t be m o n ito re d so th a t th e p ro p o rtio n o f all m in o rity ch ild ren in C a lifo rn ia ’s E M R classes reflected th e ir p ro p o rtio n in th e school p o p u la tio n . In 1984, Ju d g e P e c k h a m ’s d ec i­ sion was u p h eld by th e U n ite d States C o u rt o f A ppeals for th e N in th C irc u it.13 Ironically, as Ju d g e P eck h am w as reaching his d ecisio n , C a lifo rn ia w as in th e process o f com p letely revising its system o f special ed u c a tio n in o rd er to b rin g it in line w ith th e federal E d u ca tio n for All H a n d ic a p p e d C h ild re n A ct o f 1975. T h is law calls for m o re in d iv id u alize d p ro g ra m s o f in stru c tio n for h an d ic a p p e d ch ild ren , as well as ed u c a tio n in reg u lar classro o m s w h en ­ ever possible. U n d e r th e M aster P lan for Special E d u ca tio n , as it w as th e n called, C a lifo rn ia n o longer has an y th in g resem b lin g E M R classes o r th e E M R classification; labels are now ap p lied to types o f in stru c tio n , n o t to th e stu d e n ts, a n d very few h a n d ica p p ed stu d e n ts are co m p letely sep arated fro m th e ir n o n -h a n d ic a p p e d classm ates. M oreover, th e sta te keeps n o rec­ o rd s o f th e p ro p o rtio n o f stu d e n ts o f vario u s racial a n d e th n ic b ack g ro u n d s en ro lled in these p rogram s. All o f th is m e an s th a t u n til late 1986, in te l­ ligence tests c o n tin u e d to be used in C a lifo rn ia as o n e elem e n t o f an extensive p ro g ram o f e v a lu a tio n an d special ed u c a tio n c u rric u lu m p la n ­ n in g for b o th black an d w hite stu d e n ts, a n d th e L a r r y P. ru lin g w as vir­ tu ally u n e n fo rc e a b le .14 In D e c em b e r 1986, Ju d g e P eck h am issued a d irectiv e b an n in g sta te a d ­ m in istra tio n o f intelligence tests to all b lack ch ild ren referred for special e d u c atio n . In M ay 1987, M a ry A m aya received a le tte r fro m th e p u b lic school in R ialto , C a lifo rn ia, asking her p e rm issio n to te st h e r son, D e m o n d C raw ford, for possible p la c e m e n t in special ed u c a tio n classes. T h e le tte r c o n ta in e d a p o stscrip t ex p lain in g th a t because D e m o n d is black, th e school psychologist w ould be u n ab le to give h im an intellig en ce test. Ms. A m aya b ec am e angered th a t h er child w as being d ep riv e d o f a co m p lete analysis o f his p ro b lem s in school. U n c o n v in c e d by ex p la n a tio n s o f te st bias fro m th e N A A C P a n d L arry P.’s atto rn ey , M s. A m aya to o k h er case to th e U n ite d S tates Civil R ights C o m m issio n , w ho in Ju ly 1987 began g ath erin g facts a b o u t th e case o f D e m o n d C raw fo rd .15 T h e o u tc o m e o f th is in v estig atio n an d an y legal ac tio n M s. A m aya m ay p u rsu e co u ld have a p ro fo u n d effect on th e use o f intelligence tests in special ed u c atio n . A t presen t, it is difficult to gauge th e overall im p a ct o f th e L a r r y P. d ecision on th e use o f in d iv id u ally a d m in iste re d in telligence tests for spe­ c ia l-n e e d s stu d en ts. C o m p re h en siv e d a ta o n such test p ractices are sorely

Introduction: The IQ Controversy in Perspective

7

lacking. We do know th a t these tests can n o longer be used for th e d iagnosis o f th e special ed u c a tio n needs o f black ch ild ren in th e C a lifo rn ia p u b lic schools. M oreover, follow ing th e ap p ellate c o u rt d ecision, a challenge to test use in federal d istric t c o u rt in any state in th e N in th C irc u it (A rizo n a, Id aho, M o n ta n a , N evada, O regon, a n d W ashington) w ould p ro b ab ly lead to a sim ila r b an in tho se ju risd ic tio n s. It is also likely th a t th e fear o f litig ation has h ad a chilling effect on te st a d m in istra tio n in o th e r school d istricts, p articu la rly w here black stu d e n ts are involved. T h e legal p ro ce d u re in test challenge cases, w here adverse im p a ct (gener­ ally in te rp re ted as low er average scores by blacks o r o th e r m in o rities on tests used to m ake allocative decisions) is ta k en as p rim a facie ev idence o f d is c rim in a tio n , w as established in a 1971 S u p rem e C o u rt case in v olving em p lo y m e n t testing, Griggs v. D u k e Power C o .'6 In fact, charges o f racial d isc rim in a tio n in em p lo y m e n t p ractices th ro u g h th e use o f biased a p titu d e tests have been the m o st c o m m o n an d m o st successful fo rm o f legal c h a l­ lenge to tests in recen t years. T h e ease w ith w hich em p lo y m e n t tests are stru ck dow n derives from th e G riggs case, in w hich th e c o u rt p laced th e b u rd e n o f p ro o f u p o n th e em p lo y er in cases o f adverse im p a c t to show th a t th e te st in q u e stio n is “ a reaso n ab le m easu re o f jo b p e rfo rm a n c e ,” a n d sh o u ld be used despite in e q u alitie s in te st score betw een gro u p s. T h e c o u rt left u n an sw ered th e q u estio n o f precisely w h at such a m easu re en tails, b u t th e S u p rem e C o u rt an d low er c o u rts in su b se q u en t cases have estab lish ed th e practice o f show ing “great d efe re n ce” to th e E q u al E d u ca tio n O p p o r­ tu n ity C o m m issio n (E E O C ) G u id e lin e s on E m p lo y m e n t T estin g P ro­ cedures. (T he E E O C is charged w ith enfo rcin g T itle VII o f th e 1964 C ivil R ights A ct, d ealing w ith u n fair labor practices, a n d is th e rec ip ien t o f th o u sa n d s o f c o m p la in ts o f u n fa ir test use each year.) T h is cu sto m has dealt a v irtu a l d ea th blow to th e use o f ap titu d e tests in e m p lo y m e n t (o f seventy T itle VII cases decid ed by federal c o u rts betw een 1971 a n d 1976, 80 p e rc e n t w ere w on by th e p la in tiffs ).17 T h e E E O C G u idelines rely heavily on th e APA S ta n d a rd s fo r E d u ca tio n a l a n d P sycho­ logical T ests, w hich establishes v alid atio n criteria m e a n t p rim a rily for test d ev elo p ers w ith th e resources to c o n d u c t la rg e -scale v alid atio n stu d ies in v olving h u n d re d s o f subjects. In d iv id u al em ployers, o n th e o th e r h an d , can rarely afford to c o n d u c t such studies, a n d so m u st rely on th e v alid a­ tio n supplied by th e test m aker, w hich generally d e m o n stra te th e tests’ ab ility to pred ict p erfo rm a n c e on a w ide variety o f jo b s o f generic d escrip ­ tio n . T h e c o u rts have, in general, been unw illing to accep t such v alid atio n in cases w here th e re is adverse im p a ct; em ployers have been req u ired to show co m p re h en siv e v alid atio n d a ta specific to th e jo b o r jo b s in q u e s­ tio n .18 O n e result o f th is legal p reced en t, a n d th e clim a te o f fear p ro d u ce d by

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The IQ Controversy

g o v ern m e n t advisories on test u se ,19 m ay be th e d e v e lo p m e n t o f fairer a n d m o re valid em p lo y m e n t tests. A m ore c o m m o n rea ctio n seem s to be th e e lim in a tio n o f em p lo y m e n t testin g by m a n y firm s (a 1976 survey o f 200 co m p a n ie s fo u n d th a t 42% w ere using e m p lo y m e n t tests, c o m p a re d to 90% d o in g so in a sim ila r survey in 1963)20 in favor o f o th e r selection p ro ce d u re s (interview s, b io d a ta, etc.) th a t th e c o u rts are w illing to accept. T h a t these legally accep ted criteria all p red ic t jo b p e rfo rm a n c e less well th a n ap titu d e tests led one testin g ex p e rt to quip, “ I t’s O .K . to be fairly stu p id , b u t n o t O .K . to be unfairly stu p id .”21 E m p lo y m e n t te stin g in th e public sector, w hich is far m o re c o m m o n th a n in priv ate industry, has also suffered a declin e as a resu lt o f litig atio n . A m a jo r setback to civil service testin g ca m e w ith th e 1981 c o n se n t d ecree in volving th e federal g o v e rn m e n t’s P rofessional a n d A d m in istra tiv e C a re er E x a m in a tio n (PACE). A su it b ro u g h t again st th e U .S. C ivil Service C o m ­ m issio n in 1972 alleged d isc rim in a tio n again st black ap p lic a n ts th ro u g h th e use o f th e F ederal Service E n tra n c e E x a m in a tio n (FSEE), a te st o f verbal a n d q u a n tita tiv e rea so n in g used for e m p lo y m e n t in over 200 federal jo b s .22 W hile th e case w as o n appeal in 1975, th e Civil Service C o m m issio n rep la ce d th e FSE E w ith PACE, a carefu lly c o n s tru c te d a n d rese arch e d ex am m easu rin g five types o f ability d e m o n stra te d to be im p o rta n t to p e rfo rm a n c e in 118 jo b s. T h e five subtests co u ld be w eighted d ifferentially d e p e n d in g o n th e jo b in q u estio n . D espite its a p p a re n t w e ll-d o c u m e n te d validity, a 1979 T itle VII challenge to PACE led to a 1981 c o n sen t d ecree th a t called for th e e lim in a tio n o f th e exam over th ree years. T h e federal g o v ern m e n t, like m an y o th e r em ployers, finds itself m o v in g to w ard sep a­ rate, highly jo b - re la te d exam s fo r each jo b category. In practice, ju s t a b o u t th e o nly e m p lo y m e n t tests th a t have been ab le to m e et such challenges are th o se w ith high “ face” validity, th a t is, ac tu al w ork sam p les th a t lo o k like th e jo b being tested for. As a case in p o in t, co n sid er th e N ew York C ity Police D e p a rtm e n t’s se rg e an t’s exam . In Ju ly 1981, an ag re em e n t w as reach ed betw een th e city, th e federal g o v ern m e n t, a n d v ari­ o us m in o rity g ro u p s w ith in th e police d e p a rtm e n t in o rd e r to settle a series o f civil rights suits ch arging th a t th e se rg e an t’s ex am th e n in use d isc rim i­ n ated against m in o rity m em bers. T h e se ttle m e n t stip u la te d th a t a new test be developed, o n e specifically designed n o t to be d iscrim in ato ry . T h e test w as d eveloped by a F lo rid a firm chosen by th e city w ith th e ap p ro v al o f th e o th e r p arties to th e agreem en t. T h e new test, designed in c o n s u lta tio n w ith ex p e rts from th e city ’s police a n d p erso n n e l d e p a rtm e n ts , co st $ 5 0 0 ,0 0 0 to d evelop a n d validate. T h e test w as given to a g ro u p o f over 11,000 p olice officers in Ju ly 1983. Slightly less th a n 11 p e rc e n t o f w h ite officers passed th e test, co m p ared to on ly 1.6 p erc en t o f black an d 4.4 p e rc e n t o f H isp a n ic can d id ates. G ro u p s rep rese n tin g black a n d H isp a n ic officers ch arg ed th a t

Introduction: The IQ Controversy in Perspective

9

th e test w as racially biased a n d d e m a n d e d th a t th e resu lts be th ro w n o u t. M ayor K och expressed confidence th a t th e te st h ad been p ro p erly v alid ated a n d w as n o t biased, an d a n n o u n c e d th a t his a d m in istra tio n w ould sta n d by th e te st results. T h e c o m p la in a n ts filed related law suits claim in g th a t th e test was d isc rim in a to ry a n d sh o u ld be elim in a te d . In N o v em b er 1985 th e city a n n o u n c e d th a t it w ould n o t use th e results o f th e 1983 se rg e an t’s ex am , an d instead w ould p ro m o te police officers on th e basis o f a q u o ta system . T h is policy reversal follow ed a d e te rm in a tio n by city law yers th a t th ey co u ld n o t d e m o n stra te to a c o u r t’s satisfactio n th a t th e exam was sufficiently jo b related to w a rra n t its use d espite adverse im p act. In p a r­ ticular, ce rtain q u e stio n s o n th e exam w ere deem ed in d efen sib le as jo b related because, for exam ple, they req u ired ex am in ees to p ro d u ce from m e m o ry in fo rm a tio n a b o u t th e degree o f seriou sn ess o f v ario u s crim es, d a ta th a t sergeants co u ld look u p w hen actu ally on th e jo b . T h e city su b se­ q u e n tly began an investigation o f how o n e - h a lf m illio n d o llars co u ld have b een so m isspent. W hile th u s far escaping d irect legal challenge in c o u rt, ap titu d e test use in ad m issio n s to schools o f higher ed u c a tio n has been n o less th e su b ject o f p u b lic criticism in recen t years th a n has test use in e le m e n ta ry a n d seco n d ­ a ry schools a n d in em p lo y m e n t. In 1980, C o lu m b ia U n iv ersity stu d e n t A llan N a irn a n d his associates, w orking u n d e r th e au sp ices o f R alp h N ader, p u b lish ed T he R eig n o f E T S . In th e book, criticism s tra d itio n a lly reserved for sta n d a rd intelligence tests are d irected at tests used in ad m issio n s. N a irn et al. argue th a t tests like th e SAT a n d the Law S chool A d m issio n s Test (LSAT) are alm o st useless as p red ic to rs o f p e rfo rm a n c e in college o r law school, are racially a n d socio eco n o m ically biased, a n d are a fraud foisted on th e p u b lic by th e ETS in o rd er to keep u p profits a n d p e rp e tu a te th e ir in o rd in a te hold over test ta k ers’ lives. T he R eig n o f E T S , a n d a host o f o th e r boo k s a n d articles, are p a rt o f th e m o st recen t tre n d in th e IQ controversy: a m ove tø lessen relian ce on a d m is s io n s te sts. W h e n a 1977 C ollege E n tra n c e E x a m in a tio n B o ard (C EE B ) study p an el suggested th a t th e fifteen year d eclin e in SAT scores am o n g A m eric an high school stu d e n ts m ight be d u e in p a rt to d eclin in g ac ad e m ic sta n d ard s, th e N E A , th e c o u n try ’s largest te ach ers’ o rg an iz atio n , resp o n d e d by n am in g th e real c u lp rit— th e biased a n d in v alid SAT.23 In 1979, largely as a resu lt o f lobbying by th e N ad e r o rg an iz atio n . N ew Y ork S tate passed a tr u th - in - te s tin g law, req u irin g all a d m iss io n s -te st m a k ers to release th e c o n te n ts a n d answ ers to th e ir tests to th e g en eral p u b lic w ith in a specified tim e after test ad m in istra tio n . T h e law w as passed over th e o b jec­ tio n o f the testin g industry, w hich argued th a t such a law w ould increase test costs a n d red u ce test validity by p rev e n tin g test m ak ers from reusing q u e stio n s o f proven w orth. (W h n th e m a k ers o f th e M edical C ollege A d ­

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m ission Test [M CAT] th re a te n e d to rem ove th e ir te st from th e state ra th e r th a n a tte m p t th e nearly im possible task o f c o n s tru c tin g a co m p letely new a n d equally valid exam on each a d m in istra tio n , th e legislators acq u iesced by g ran tin g an ex e m p tio n to th e M CAT a n d c e rta in o th e r tests d raw n from a lim ite d co rp u s o f know ledge.) S im ilar legislation w as su b seq u en tly p ro ­ posed in the U .S. C ongress, forcing E TS to a n n o u n c e a p o licy o f v o lu n ta ry d isclosure n atio n w id e in o rd e r to u n d e rc u t w h at th ey feared w ould be an even h a rsh e r law. (O n e o f th e goals o f th e new o rg an iz atio n FairT est is to get such a n a tio n a l law passed.) T h e effect o f pu b lic d eb a te o n ad m issio n s test p ractices is difficult to gauge. In 1969, B ow doin C ollege in B runsw ick, M ain e, b ecam e th e first m a jo r college in th e U .S. to sto p req u irin g stu d e n ts to su b m it SAT scores. W hile it h ard ly caused a tid al wave, B ow doin has been jo in e d by a h an d fu l o f o th e r colleges in rec en t years. H arv ard C ollege has co n sid ered a ch an g e in ad m issio n s policy w hereby ap p lic a n ts w ould be able to su b m it ach iev e­ m e n t test scores in specified subjects in lieu o f SAT scores. In 1985, th e H a rv a rd B usiness S chool a n n o u n c e d th a t it w ould no lo n g er req u ire ap p li­ c a n ts to su b m it G ra d u a te M a n a g e m e n t A dm issio n Test (G M A T ) scores, an d Jo h n s H o p k in s M edical S chool a d o p te d th e sam e policy reg ard in g M CATs. T h e m oves by H a rv a rd a n d Jo h n s H o p k in s m ay be p ro g n o stic, in light o f these schools’ tra d itio n a l role as bellw eth ers in th e ed u c atio n al co m m u n ity . A t p resen t, however, it is n o t clear th a t th e con tro v ersy has h ad m u c h o f an effect on ad m issio n s test use besides these iso lated in stan ces. F or o n e th in g , m o st colleges are n o t very selective. W hile v irtu a lly every fo u r-y e a r college in th e U n ite d S tates req u ires ap p lic a n ts to su b m it eith er SAT o r A m eric an C ollege T esting (A C T) scores, th e vast m a jo rity o f college ap p li­ c a n ts are accep ted by eith er th e ir firs t- o r se c o n d -c h o ic e schools.24 T h u s, it is o n ly a t a sm all n u m b e r o f th e m o st selective colleges, a n d at g rad u a te a n d p ro fe ssio n a l schools, th a t a d m issio n s c rite ria are im p o r ta n t a t all. O f course, th e m o st selective schools are also th o se a ttra c tin g th e m o st ta l­ e n te d ap p lica n ts. It th e re fo re often b ecom es necessary for th ese sch o o ls to decide am o n g a g ro u p o f ap p lica n ts, alm o st all o f w h o m w ould p ro b ab ly succeed if a d m itte d , o n th e basis o f sm all differences in high school o r college grades, test scores, o r o th e r factors. W h en ta le n te d stu d e n ts are d en ied ad m issio n to a p restigious univ ersity p a rtia lly as a resu lt o f a sm all n u m b e r o f q u e stio n s m issed on a f o u r- h o u r ex am p u rp o rte d to m easu re “ scholastic a p titu d e ,” c o m p la in ts in ev itab ly will be heard. T h ere is m o re to th e contro v ersy a b o u t ad m issio n s tests, however, th a n a h an d fu l o f unsuccessful Ivy L eague ap p lica n ts. T h e ce n tral issue in th e p u b lic d e b a te over in te llig en c e a n d a p titu d e te stin g is th a t th ese tests, w h eth e r in th e schools, o n th e jo b , o r in adm issio n s, are being used to

Introduction: The IQ Controversy in Perspective

11

allo cate im p o rta n t resources an d o p p o rtu n itie s by ra n k in g people a c co rd ­ ing to “ in tellig en ce” o r “ a p titu d e ” on th e basis o f a very sm all sam p le o f behavior. E d u ca tio n a l an d o cc u p atio n al resources are lim ited , a n d d ec i­ sio n s a b o u t th e ir allo ca tio n m u st be m ade. T raditionally, A m erican s have a tte m p te d to m ak e such decisions o n the basis o f m erit, an d tests have been seen as one objective c riterio n for d oing so. P ublic co n tro v ersy arises w hen th e tests help p ro d u ce allocative decisions th a t ru n c o u n te r to o u r ideals a b o u t fair an d eq u itab le tre a tm e n t, nam ely, w hen th e re are significant g ro u p differences in th e d istrib u tio n o f ed u c atio n al a n d em p lo y m e n t o p ­ p o rtu n itie s. Elence, th e o u tc ry against Jen sen , th e L a r r y P. d ecisio n , an d th e c u rre n t em p lo y m e n t testin g clim ate. T h e key to u n d e rsta n d in g th e IQ co n troversy lies in th e h istorical conflict betw een tw o stran d s in A m erican th o u g h t, th e desire for increasingly efficient a n d objectiv e assessm ent, an d th e b elief in h u m a n eq uipotentiality. Early Developm ents T h e p u b lic atio n o f C harles D a rw in ’s O n the O rigin o f Species in 1859 w as a sem in al ev en t in the d ev e lo p m e n t o f intelligence a n d ap titu d e tests. Testing, o f w h atev er form , has as its fu n d a m e n ta l goal th e m e a su re m e n t o f in d iv id u al differences. Tests o f m en tal ac h ie v em e n t, i.e., know ledge, h ad been used in th e schools a n d in em p lo y m e n t long befo re D arw in (the C h inese have had a system o f civil service e x a m in a tio n s for m o re th a n 3,000 years), b u t w ith th e th e o ry o f ev o lu tio n cam e an in te rest in dif­ ferences in in n a te ability as well. D arw in h im self had little to say a b o u t psychological ch aracteristics; he w as m o re c o n c e rn e d w ith n a tu ra l v ariatio n in physical stru c tu re a n d fu n c­ tio n . T h e ap p lica tio n o f D arw in ia n prin cip les to th e psychological realm th erefo re fell to D a rw in ’s h a lf-c o u s in , F ran cis G alto n . A tru e R en aissan ce m a n , G a lto n m a d e significant c o n trib u tio n s in the fields o f statistics, m e te ­ orology, geography, an d crim inology, am o n g others. H e is p ro b ab ly best k n ow n, however, as th e fo u n d e r o f eugenics, th e b elief th a t h u m a n ity can be im p ro v ed th ro u g h selective breeding. G a lto n believed th a t im p o rta n t differences betw een people w ere largely th e resu lt o f differences in in h e rited abilities. In s u p p o rt o f his thesis, G alto n p u blished a genealogical stu d y in 1869 en title d H ere d ita ry G enius. Selecting a rep rese n tativ e sam p le from v ario u s d irecto ries o f fam o u s m en, G a lto n in q u ire d in to th e sta tu s o f th e ir relatives. H e fo u n d a m u c h higher p ro p o rtio n o f em in en c e w ith in th e fam ilies o f his sam p le th a n w ould be expected by ch an ce. M oreover, th e clo ser th e relative, th e m o re likely th a t he o r she w as e m in e n t, a n d th e g reater th e sim ilarity in th e field in w hich em in en c e w as achieved. W hile recognizing th a t th e relatives o f these high achievers m o st likely sh ared

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The IQ Controversy

su p e rio r en v iro n m e n ts as well as su p e rio r genes, G a lto n was co n v in ce d th a t m o st o f th e differences in a c h ie v em e n t betw een m en w ere th e resu lt o f differences in n a tu ra l ability, p rim a rily intelligence. W hile biographical d irec to ries prov id ed a useful in d ic a to r o f n a tu ra l ability, G a lto n n eeded a m o re d irec t m easure. I f eugenics w as to b eco m e a practical reality, it was necessary to have a m e th o d for id en tify in g th o se w ith n atu ra l ta le n t a t an early age. In a tte m p tin g to dev elo p such a m e a­ sure, G a lto n began w ith th e assu m p tio n , c o n siste n t w ith B ritish em p iricist tra d itio n , th a t w h at we know is ac q u ired th ro u g h o u r senses. D ifferences in p ercep tu al speed a n d acu ity m u st th erefo re be cru cial to differences in intellect. In 1884, initially as p a r t o f th e In te rn a tio n a l H ea lth E x h ib itio n in L o n d o n , a n d la te r as p a rt o f th e Science M u se u m in S o u th K en sin g to n , G a lto n set u p an A n th ro p o m e tric L aboratory. V isitors to th e la b o ra to ry co u ld , for a sm all fee, have v arious m e asu rem en ts ta k en a n d recorded. Besides gross physical m e a su re m e n ts o f height, w eight, a n d so fo rth , th e la b o ra to ry c o n ta in e d n u m e ro u s m e asu res o f n eu ro lo g ical a n d se n so ry fu n ctio n in g , such as sim ple rea ctio n tim e, visual a n d a u d ito ry sensitivity, co lo r p erc ep tio n , a n d steadiness o f h an d . F ar from a ca rn iv al sideshow, G a lto n ’s la b o ra to ry was able to collect reliable d a ta from o ver 9,000 in d i­ viduals; th is w as th e first a tte m p t at th e scientific m e a su re m e n t o f in d iv id ­ ual differences in psychological ch aracteristics. T h e w ork o f su m m arizin g th ese d a ta by age, sex, etc., a n d o f describ in g th e in te rre la tio n sh ip s betw een th e v arious m easu res a n d classifications, led to th e d ev e lo p m e n t o f im p o r­ ta n t statistical te c h n iq u e s for m easu rin g significance a n d co rrela tio n . As G alto n was m a k in g his re a c tio n -tim e an d sen so ry m e a su re m e n ts at S o u th K en sin g to n , th e first im p o rta n t w ork in ex p e rim e n ta l psychology w as b ein g c o n d u c te d in th e L eip zig la b o ra to rie s o f W ilh e lm W u n d t. W u n d t used m a n y o f th e sam e m e a su re m e n ts as G alto n , b u t to a d ifferen t p u rp o se. W u n d t w as interested , n o t in in d iv id u al differences in m e n ta l fu n ctio n in g , b u t in th e stru c tu re o f th e m in d th a t w as co m m o n to all in div id u als. O n e o f his stu d e n ts, an A m eric an n a m e d Ja m es M cK een C attell, was in terested in stu d y in g in d iv id u al differen ces in rea ctio n tim e. W hile u n ab le to in te rest W u n d t in th e idea, C attell h ad h ea rd o f G a lto n ’s w ork in E ngland an d a rra n g e d to stu d y w ith him . Follow ing his te n u re in E n gland, C attell re tu rn e d to th e U n iv ersity o f P en n sy lv an ia, w here he b e c a m e th e w o rld ’s first p ro fe sso r o f p sycholog y (p sy ch o lo g y h ad p re ­ viously been a sub d iscip lin e o f philosophy). A t P en n , C attell estab lish ed th e first univ ersity la b o ra to ry d ev o ted to th e psychological m e a su re m e n t o f in d iv id u al differences, w ork he c o n tin u e d a t C o lu m b ia U niversity. In 1890, C attell co in ed th e te rm “ m e n ta l tests” to describe th e series o f stren g th , se n sa tio n , r e a c tio n - tim e , a n d m e m o ry ta sk s he a n d h is s tu d e n ts d e ­ velo p ed .25 C a tte ll-ty p e testin g flourished d u rin g th e n ex t decade, w hich

Introduction: The IQ Controversy in Perspective

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saw C attell beco m e th e first c h a irm a n o f the APA’s C o m m itte e on M en tal a n d Physical Tests. T h e sensory a n d re a c tio n -tim e ap p ro a ch to m e n tal testin g w as h u rt badly in 1901 by o n e o f C a tte ll’s ow n g rad u ate stu d en ts, C lark W issler.26 In th e first c o rrela tio n a l study o f m e n ta l te st results, W issler o b ta in ed m e n ta l test scores a n d ac ad e m ic grades from over 300 C o lu m b ia a n d B a rn a rd College stu d en ts. H e fo u n d v irtu ally n o c o rre la tio n betw een m e n tal test scores a n d ac ad e m ic grades. A p rofessional controv ersy over th e validity o f th e W issler results an d th e C attell tests e n su e d .27 b u t qu ick ly b ecam e m o o t as d ev e lo p m e n ts in F ran ce forever ch anged th e face o f m e n tal testing. In 1895 F ren ch psychologist A lfred B inet an d his stu d e n t V icto r H en ri p u b lish ed an article in B in et’s new ly fo u n d ed jo u rn a l, L ’A n n é e P sychol­ ogique, en title d “ La Psychologie Individuelle." B inet a n d H en ri o u tlin ed w h at they called an in d iv id u al psychology. W hile g eneral psychology was c o n c e rn e d w ith th e general p ro p ertie s o f “psychic p rocesses," in d iv id u al psychology h ad as its aim th e study o f how these processes differ from in d iv id u al to in d iv id u al, a n d betw een th em selves w ith in th e sam e in d iv id ­ ual. To th is en d , th e a u th o rs critically e x a m in e d th e th e n m o st p o p u la r m e th o d for stu d y in g in d iv id u al psychic differences, th e C a tte ll-ty p e tests o f sim ple sensory a n d m e m o ry processes. T hese tests w ere criticized as b eing to o n arro w in focus an d to o sim ple to p ro d u ce m ean in g fu l in d iv id ­ ual differences. B inet a n d H en ri p roposed th a t th e p ro p er m e th o d for stu d y in g in d iv id u al psychology req u ired a w ide variety o f tests o f different types in o rd er to give a m o re co m p lete profile o f in d iv id u al psychic fu n c­ tio n in g . F urther, th ey argued th a t a t least som e o f these tests m u st ta p th e h igher m en tal fu n ctio n s, such as im a g in a tio n a n d c o m p re h en sio n , for it is th e re th a t o n e finds m o st significant in d iv id u al differences. R ecognizing th a t th e m e a su re m e n t o f these higher fu n ctio n s w ould involve a ce rtain loss o f p recision as co m p ared to sim ple rea ctio n tim e an d m e m o ry tasks, th e a u th o rs w ere no n eth eless co n fid e n t th a t th e rich n ess o f th e d a ta w ould ov ercom e an y obstacles. T h e B inet an d H en ri article drew th e b a ttle lines q u ite clearly betw een th e C attell an d B inet schools o f m e n tal testing. As ev id en ce accu m u lated , however, it becam e o b vious w here th e fu tu re lay. B inet w as able to draw su p p o rt from w ork by O e h rn , E bbinghaus, a n d o th ers, show ing th a t m o re co m p lex m e m o ry tests w ere su p e rio r to sim ple task s in d isc rim in a tin g th e m e n tal cap ab ilities o f stu d e n ts a n d m e n tal p atien ts. A n 1899 artic le by S tella S harp, a C o rn ell g rad u a te stu d e n t, directly c o m p ared C a tte ll-ty p e to B in e t-H e n ri-ty p e tests in an ex p e rim en tal settin g .28 W hile skeptical ab o u t th e overall value o f in d iv id u al psychology (S harp was a s tu d e n t o f E. B. T itchener, th e leading A m erican p ro p o n e n t o f W u n d t’s school o f general psychology). S h arp co n clu d ed th a t th e B in e t-H e n ri ap p ro a ch o f using var-

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ied tests o f higher m e n tal fu n ctio n s w as su p e rio r in th e id e n tifica tio n o f in d iv id u al differences. M o st o f th e d a ta a n d m eth o d o lo g y in favor o f th e B in e t-H e n ri ap p ro a ch ca m e from B inet him self. T h ro u g h o u t th e 1890s B in et a n d his stu d e n ts d eveloped tests o f vario u s higher m e n ta l fu n ctio n s such as verbal m em ory, suggestibility, a n d p ic tu re d escrip tio n , using F ren ch sch o o lch ild re n as su b ­ jects. In his w ritings, B inet suggested th a t w hen d ealin g w ith h ig h er fac­ u ltie s su c h as im a g in a tiv e n e s s , w h e re th e re is n o a b s o lu te sc ale o f m e a su re m e n t, th e on ly m e an in g fu l te st m easu res are in te rin d iv id u a l. In o th e r w ords, te st q u estio n s o f th is type m u st be scaled ac co rd in g to how ex a m in e es actu ally p erfo rm o n th e tasks. A n o th e r m a jo r ad v a n ce in th e d ev e lo p m e n t o f th e intelligence te st cam e in a 1900 p ap e r by B in et in w hich he developed a series o f tests fo r “a tte n tio n .” H e first asked a P aris sch o o l­ te ac h er for th e five “ m o st in te llig en t” a n d six “least in te llig en t” ch ild ren in h e r class.29 B inet began w ith a large series o f tests, e lim in a tin g th o se th a t d id n o t differentiate betw een th e tw o g ro u p s o f ch ild ren . T h e p ractice o f d irect co m p ariso n to in d e p e n d e n t criteria w as to b ec o m e critical to la ter in telligence te st d ev elo p m en t. B in et’s o th e r m a jo r c o n c e rn d u rin g th is p erio d w as th e u n reliab ility o f th e m e th o d s th e n in use for th e diagnosis a n d classification o f th o se in h osp itals for th e m e n tally defective a n d for th e id e n tifica tio n o f a b n o rm a l sc h o o lch ild ren . T hese m e th o d s w ere an y th in g b u t sta n d ard iz ed , v ary in g w idely from e x a m in e r to exam iner, a n d in c lu d in g such diverse m e asu res as B in e t- a n d C a tte ll-ty p e m e n tal tests, subjective im p ressio n s o f cleanliness, a n d m edical ex a m in a tio n s. L ittle a tte m p t h ad been m a d e to regulate th ese p ractices o r to d e te rm in e if th e tests bein g used w ere in fact related to in tellectu al fu n ctio n in g . B inet believed th a t he co u ld ap p ly his d ev elo p in g set o f m en tal tests to these fu n ctio n s in a m o re sy stem atic way. H is o p p o rtu n ity ca m e in 1904, w hen th e m in iste r o f p u b lic in stru c tio n set u p a co m m issio n to stu d y th e e d u c a tio n a l p ro b lem s o f s u b n o rm a l sch o o lch ild re n in Paris. In o rd e r for these ch ild ren to receive th e special ed u c a tio n th ey need ed , it w as necessary to find an o b jectiv e way o f id e n ti­ fying tho se m o st in need o f help. B inet a n d his s tu d e n t T h eo d o re S im o n w ere charged w ith d eveloping such a test. T h e resu lt o f th e ir efforts, th e 1905 B in e t-S im o n scale, is generally co n sid ered th e first usable intelligence te st.30 T h e value o f th e B in e t-S im o n scale w as d erived fro m a series o f featu res B inet h ad been w orking on d u rin g th e p rev io u s decade: •

T h e test was, as B inet an d S im on called it, a “ M etrical Scale o f In te l­ ligence.” T h e th irty test item s w ere arra n g e d in o rd e r o f in creasin g diffi­ culty, w ith difficulty levels established th ro u g h sta n d a rd iz a tio n o n b o th

Introduction: The IQ Controversy in Perspective

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n o rm a l a n d s u b n o r m a l c h ild re n aged th re e to elev en in th e P aris schools. • T h e test ite m s w ere age graded. It was rep o rted , for ex am p le, th a t th e average th re e -y e a r-o ld m ade it th ro u g h item 9, w hile fiv e -y e a r-o ld s co rrectly answ ered item s th ro u g h n u m b e r 14 (sta n d a rd iz a tio n w as only p rovided for o d d -n u m b e re d years in the 1905 scale). Test scores w ere th u s re p o rte d n o t in te rm s o f an ab so lu te level o f intelligence, b u t by c o m p arin g a s tu d e n t’s m e n tal age (a g e -e q u iv a le n t o f highest q u estio n answ ered correctly) to his o r h er chronological age. R e ta rd a tio n o r a d ­ v an c em en t was re p o rte d in years. (In o rd er to elim in a te n o n lin e arities in th is m e th o d o f rep o rtin g te st scores— a fiv e -y e a r-o ld p e rfo rm in g at th e th re e -y e a r-o ld level is actu ally m o re reta rd e d th a n an e le v e n -y e a rold w ho tests as a n in e -y e a r -o ld — G e rm a n psychologist W illiam S tern , in 1911, p ro p o sed th e use o f th e “ m e n ta l q u o tie n t,” in w hich a ch ild ’s m en tal age is d iv id ed by his o r her chron o lo g ical age.31 T oday’s in te l­ ligence q u o tie n t, o r IQ, is deriv ed from th is m easu re, a n d is essentially th e m en tal q u o tie n t m u ltip lie d by 100.) It w as th e g en iu s o f B inet to sta n d ard iz e m e n tal age. B inet u n d e rsto o d th a t intelligence, w h atev er it is, increases d u rin g ch ild h o o d , an d th a t it is m o re fru itfu l for a p sy ch o l­ ogy o f in d iv id u al differences to c o n c e n tra te o n relativ e levels o f in te l­ ligence th a n to try to m easu re such a n eb u lo u s c o n c ep t in ab so lu te term s. • T h e scale item s tested a w ide variety o f sim ple a n d h ig h er m e n tal fu n c­ tio n s in o rd e r to provide a m o re co m p lete p ic tu re o f th e c h ild ’s in te lle c­ tu a l fu n ctio n in g . T h u s, for exam ple, item 1 m e asu red sim p le visual co o rd in a tio n , in w hich th e child h ad to m ove head an d eyes in o rd er to follow a lighted m a tch passed before th e eyes. In ite m 5, th e ch ild was req u ired to rem ove a p ap e r w rap p er from a piece o f ch o co late. Item 11 asked ch ild ren to rep e at a series o f th ree digits follow ing oral p re se n ta ­ tio n . Item 20 ask ed fo r th e rese m b la n ce betw een g ro u p s o f v ario u s n a m e d objects, such as a w ild pop p y a n d b lood , o r an a n t, a fly, a n d a butterfly. Item 30, th e m o st difficult in th e scale, asked for th e d istin ctio n betw een such ab stra ct te rm s as “ lik in g ” a n d “ respecting.” T h e te st th u s p rovided a m easu re o f general in tellectu al capacity, ra th e r th a n o f th e m o re specific fu n ctio n s m e asu red by ea rlier tests develo p ed by B inet an d others. T h e m o st im p o rta n t featu re o f th e B in e t-S im o n scale, o f course, was th a t it w orked. T h e 1905 scale, a n d even m o re so its 1908 revision, proved to be ex trem ely useful for identifying th e retard ed . In a d d itio n , th e B in e tS im o n scale p rovided a general r a n k -o rd e rin g o f n o rm a l a n d su b n o rm a l stu d e n ts th a t w as co n siste n t w ith o th e r in d ic ato rs o f intelligence such as te a c h e r a n d p eer e v a lu a tio n s a n d ease o f trainability , b u t d id so in a m o re efficient an d reliable m a n n e r th a n th e o th e r m easures. Typical o f th e reactio n to th e scales w as th a t o f H. H. G o d d a rd , w ho in

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1910 tran slate d th e 1908 scale in to E nglish for use in th e U n ite d S tates. A t first skeptical th a t o n e co u ld m easu re global in tellig en ce in th e ex act way B inet an d S im o n p roposed, G o d d a rd w as am az ed by th e scale’s accu racy w hen he began to use it a t his V in elan d , N ew Jersey school for feeble­ m in d e d children. A n o th e r A m eric an psychologist p a rtic u la rly im p ressed by th e B in e tS im o n scales w as Lew is T erm an . As a g ra d u a te stu d e n t a t C lark U niversity, T erm an h ad been w orking o n his ow n intelligence scale b ased o n h igher m e n ta l processes w hen th e first B in e t-S im o n scale w as p u b lish ed . In 1916, as a p rofessor o f psychology a t S tan fo rd U niversity, T erm a n p u b lish ed th e S tan fo rd R evision o f th e B in e t-S im o n scale,32 b ased p artially on his ow n w ork a n d p artially on th e final 1911 revision (B in et died in th a t year) o f th e B in e t-S im o n . T e rm a n ’s test, w hich in its su b se q u en t revision has c o m e to be k now n as th e S ta n fo rd -B in e t, b ecam e th e sta n d a rd by w hich all later intelligence tests have been judged. The Army Tests and the First Controversy T h e great need for reliable selection devices an d th e en th u sia sm o f th e early A m erican m e n tal testers very q uickly led to w id esp read in telligence te st use in th e U n ite d States in th e years before W orld W ar I. T h e m o st c o m m o n use w as for th e screening o f ch ild ren a n d th e id e n tifica tio n o f th e fe e b le -m in d e d in pu b lic a n d priv ate schools. In tellig en ce tests w ere also a d m in iste re d in o th e r in stitu tio n s, in c lu d in g ho sp itals, p riso n s a n d in san e asy lu m s. M a n y o f th ese in s titu tio n a l a p p lic a tio n s w ere s m a ll-s c a le re ­ search projects, however. L arg e-sc ale intelligence a n d a p titu d e te stin g in th e school an d w orkplace w as p rec lu d ed by th e expensive a n d tim e - c o n ­ su m in g n a tu re o f in d iv id u al te st a d m in istra tio n . T h e sta tu s o f m e n tal testin g ch anged d ram a tic ally w ith th e first la rg e scale usage o f gro u p intelligence tests d u rin g W orld W ar I. T h e d ev elo p ­ m e n t o f intelligence tests alo n g th e B in e t-S im o n m o d el th a t co u ld be ad m in iste re d to a large g ro u p sim u lta n eo u sly h ad been progressing slowly in th e years p receding th e war. A s early as 1910, B in et a n d S im o n h ad discussed th e feasibility o f g ro u p testing o f a rm y rec ru its.33 T h e m o st n o ta ­ ble progress w as m ad e by A rth u r O tis, a s tu d e n t o f T e rm a n ’s at S tan fo rd , w ho in 1917 dev eloped an objectively scored p a p e r -a n d -p e n c il test th a t T erm a n claim ed p ro d u ce d scores alm o st id en tical to th e in d iv id u a lly -a d ­ m in iste re d S ta n fo rd -B in e t.34 O tis’ test served as an im p o rta n t m o d el for th e W orld W ar I A rm y exam s. W hen th e U n ite d States e n te re d th e w ar in 1917, R o b e rt Y erkes o f H arv ard , th e n p resid e n t o f th e APA, q u ick ly m o b i­ lized psychologists to aid th e w ar effort, a n d to p ro m o te th e u sefulness o f th e ir n ascen t en terp rise. A m o n g th e c o m m itte e s fo rm e d w as o n e ch a ired

Introduction: The IQ Controversy in Perspective

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by Yerkes, on M e th o d s o f Psychological E x am in in g o f R ecru its. Y erkes assem bled in V in elan d , N ew Jersey a gro u p o f A m eric a’s leading m e n ta l testers, in c lu d in g T erm a n a n d G o d d a rd , for the p u rp o se o f d ev elo p in g a g ro u p -a d m in is te re d test th a t w ould aid in p lacing rec ru its in to ap p ro p ria te jo b s a n d co u ld id en tify tho se in c o m p e te n t to serve. T h e results o f th e ir efforts, as accep ted for use by th e arm y, w ere th e A lp h a a n d B eta exam s. T h e A lpha c o n ta in e d q u estio n s in such areas as a rith m etica l reasoning, n u m b e r series c o m p le tio n , a n d an a lo g ie s— categ o ries sim ila r to th o se fo u n d in the S ta n fo rd -B in e t a n d m an y p re se n t-d a y intelligence tests. T h e Beta, in te n d ed for use w ith illiterate recruits, co n ta in e d sim ila r q u estio n s, b u t in purely p icto rial form . Yerkes, an d th e A rm y D ivision o f P sychology th a t he h ead ed , supervised th e a d m in istra tio n o f th e A lpha a n d B eta to nearly 2 m illio n A rm y re­ cru its. T h e im p a c t these test results h ad o n th e w ar effort is u n ce rtain . W hile nearly 8,000 recru its w ere re c o m m e n d e d for disch arg e as m en tally in c o m p e te n t, a n d th o u sa n d s o f o th ers w ere assigned ac co rd in g to th e ir test scores,35 m an y A rm y officers w ere skeptical o f th e su d d e n ly u b iq u ito u s m e n tal testers an d th e ir “ scientific” in stru m e n ts a n d refused to use the results. N onetheless, th a t Y erkes a n d his g ro u p o f testers w ere able to d ev elop th e tests a n d organize th e ir a d m in istra tio n to so m a n y recru its u n d e r w a rtim e c o n d itio n s d e m o n stra te d th e feasibility o f larg e-scale g ro u p in telligence testing. T h e success o f th e A rm y tests, at least from a logistical perspective, a n d th e experience gained in develo p in g these a n d m o re specific a p titu d e tests d u rin g th e war, tra n sfo rm e d psychology from an ac ad e m ic d iscip lin e in to a profession. A fter th e war, th e new g ro u p -te stin g tech n o lo g y w as ap p lied on a regular basis in schools a n d industry. T h e rapidly ex p a n d in g an d ch a n g ­ ing A m erican p o p u la tio n an d social stru c tu re o f th e first p a rt o f th is c e n ­ tu ry created a d esp erate need for efficient selection tools, a n d th e m en tal testers were only to o h ap p y to help o u t. M en tal testing, to u te d as th e scientific so lu tio n to selection prob lem s, fit nicely w ith p o p u la r Progressive ideas o f reshaping society th ro u g h th e ratio n al a p p lica tio n o f science. By 1921, 2 m illion A m erican sch o o lch ild ren w ere being tested by on e o r a n ­ o th e r gro u p intelligence test, m ostly for p la c e m e n t in h o m o g e n eo u s class­ r o o m s ( t r a c k i n g ) .36 A d d itio n a lly , i n d i v i d u a l l y - a d m i n i s t e r e d te s ts c o n tin u e d to be w idely used for th e id e n tifica tio n a n d p la ce m en t o f spe­ c ia l-n e e d s stu d en ts. T h e ap p lica tio n o f the new selection to o ls after W orld W ar I w as p ar­ ticu larly ev id en t in em p lo y m e n t, w here th e e n th u sia sm w ith w hich m an y em ployers accepted intelligence tests reflected a p erc ep tio n o f th e tests as m a jo r too ls o f efficiency. In th e years im m ed ia te ly follow ing th e war, h u n ­ d red s o f c o m p an ie s began to use co m m ercially available tests to m ak e

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e m p lo y m e n t decisions, w hile on ly a h an d fu l o f firm s d ev o ted th e reso u rces necessary to develop p ro p e r testin g p ro g ra m s.37 T h is sta te o f affairs w as p artially th e resu lt o f sa lesm an sh ip by m a n y o f th e m e n ta l testers, w ho w ere an x io u s to ap p ly th e ir new technology, even in cases w here, as so m e o f th e ir colleagues w arn ed , tests h ad n o t been sufficiently v alid ated fo r th e uses to w hich th ey w ere being put. Besides p u ttin g psychology o n th e m ap, th e A rm y tests h ad a n o th e r co n seq u en ce: they set off th e first p u b lic contro v ersy a b o u t in telligence testing. T h e A rm y d a ta revealed th a t m e m b ers o f im m ig ra n t gro u p s, o n th e average, scored low er th a n n a tiv e -b o rn A m erican s, a n d th a t im m ig ra n ts from so u th e rn a n d e a ste rn E u ro p e (w ho w ere in g eneral m o re recen t a rriv ­ als) scored low er th a n th o se from n o rth e rn a n d w estern E u ro p e. Black rec ru its scored low est o f all. M oreover, based o n th e ag e -g ra d e d sta n d a rd s in use, th e average m e n tal age o f all A rm y rec ru its w as 13. T h e im m ig ra n t d a ta w ere seized u p o n by C arl B righam , an assistan t p rofessor o f psychology a t P rin c eto n , w hose 1923 b o o k A S tu d y o f A m e r ­ ican Intellig en ce is a racist treatise by an y sta n d ard . B righam arg u ed th a t th e A rm y d a ta d e m o n stra te d th e w e ll-k n o w n in ferio rity o f th o se o f M ed i­ te rra n e a n stock, as c o m p ared to th e N o rd ic races o f n o r th e r n E u ro p e. H is co n c lu sio n w as th a t th e U n ite d States m u st restrict im m ig ra tio n from so u th e rn a n d e a ste rn E u ro p e in o rd er to keep th e A m eric an gene pool fro m d eterio ratin g . W hile B rig h a m ’s b o o k a p p a re n tly h ad little in flu en ce in p olitical circles, it is evidence th a t th e sam e racism a n d x e n o p h o b ia th a t p ro d u c e d th e restric tio n ist Im m ig ra tio n A ct o f 1924 w ere am en a b le to th e te stin g d ata. Sim ilarly, p o p u la r eugenicist w riters w ere q u ic k to p o in t to th e average m e n ta l ability o f A rm y recru its (despite th e A rm y testers’ ow n w arn in g s th a t th e n u m b e rs sh o u ld n o t be in te rp re te d to o literally) as a w arn in g th a t we m u st a c t q u ick ly to im prove o u r b ree d in g stock. (T h e A rm y d a ta fit nicely w ith th e increasingly p o p u la r A m eric an eugenics m o v em en t; by th e m id 1930s, 24 states h ad laws m a n d a tin g sterilizatio n for th o se w ith c e rta in h eritab le defects, in c lu d in g fe e b le -m in d e d n e ss.)38 T h e rea ctio n o f m a n y w ho fo u n d th e co n c lu sio n s b ein g d raw n fro m th e A rm y results a b h o rre n t w as to a tta c k n o t on ly th e co n c lu sio n s b u t th e tests them selves. C e rta in c o n te m p o ra ry critics, m o st n o ta b ly S tep h en Jay G o u ld in T h e M ism e a su r e o f M a n a n d L eon K am in in T h e S cien ce a n d P olitics o f IQ , have sought to a tta c k th e testin g edifice by exposing its racist fo u n d atio n s. T h e y arg u e th a t th e early m e n ta l te ste rs p ro p a g a te d in te llig en c e tests largely as a m e an s o f d e m o n stra tin g th e in h e re n t su p e rio rity o f m id d le a n d u p p e r-c la ss w hites, a n d th a t to d a y ’s tests a n d th o se w h o s u p p o rt th em rep rese n t th e sam e agenda. A c o m m o n ta ctic used by such w riters is to describe in detail o n e ex tre m e case, like B righam , a n d th e n argue th a t it is

Introduction: The IQ Controversy in Perspective

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ty p ical o f th e m e n ta l-te s tin g c o m m u n ity as a w hole. In fact, racism was p ro b ab ly less c o m m o n am o n g th e early m e n tal testers th a n am o n g th e rest o f th e p o p u la tio n o f th e tim e. O n ce testin g e n te re d its p erio d o f m o st rap id a n d so p h isticated d e v e lo p m e n t in th e 1930s, th e re is no longer ev idence o f racist influence. T h e long h isto ry o f a tte m p ts by m a in stre a m p sy c h o m etri­ cian s to develop c u ltu re -fa ir tests is o n e in d ic a tio n th a t tests have been m o re th a n too ls for m a in ta in in g th e sta tu s quo. F re q u en tly q u o te d in ac c o u n ts o f th e in h e re n t racism o f testin g is K am in ’s d escrip tio n o f H. H . G o d d a rd ’s assessm ent o f new ly arriv in g im m i­ g ran ts a t Ellis Island: “ 83% o f th e Jews, 80% o f th e H u n g aria n s, 79% o f th e Italian s, an d 87% o f the R ussian s w ere ‘feeblem in d ed .’”39 G o d d a rd does in d eed re p o rt these n u m b e rs, b u t K am in a n d tho se w h o cite h im fail to tell th e ir readers th a t G o d d a rd d id n o t believe th e g ro u p s tested to be rep rese n ­ ta tiv e o f im m ig ra n ts from th o se co u n tries, n o r was he w illing to a ttrib u te th e ir fe e b le -m in d e d n e ss to genetic causes.40 It is also n o t th e case th a t th e A rm y testing d a ta w ere in an y way im p o rta n t to th e passage o f th e Im m i­ g ratio n A ct o f 1924, rep o rts by S tep h en Jay G o u ld an d L eo n K am in n o t­ w ith stan d in g . A n ex a m in a tio n o f th e relev an t legislative h isto ry reveals th a t th e A ct w ould have been passed had the testin g d a ta n ev er ex isted .41 T h a t th e G o u ld /K a m in h isto ry is so u n critically re p o rte d in th e new s m edia a n d elsew here is a n o th e r ex am p le o f th e pervasiveness o f a n ti­ testin g se n tim e n t today. T h e p o st-W o rld W ar I m e n ta l-te stin g co m m u n ity , w hile obviously n o t w illing to c o n d e m n te stin g as a w hole, co u ld be fo u n d o n b o th sides o f th e d eb a te over th e A rm y d ata. M an y psychologists a n d e d u c a to rs w ere critical o f B righam ’s b o o k a n d o f tho se w ho w ould draw stro n g co n c lu sio n s from th e obviously flawed A rm y tests.42 It w as p o in te d o u t, for ex am p le, th a t on six o f the eight subtests o f th e A lpha th e m o st c o m m o n score w as zero, an in d ic a tio n th a t th e test was to o difficult, a n d th erefo re m ean in g less as a m easu re o f intelligence. T h o u g h in te n d e d as m easu res o f n ativ e ability, it w as clear th a t th e tests w ere to o d e p e n d e n t o n specific c u ltu ral know ledge, a flaw p a rtic u la rly o n ero u s to rec en t im m ig ran ts. P hysical c o n d itio n s var­ ied across test a d m in istra tio n s, often involving c ra m p e d q u a rte rs a n d in a d ­ e q u a te lighting an d acoustics. M ental age ca lc u latio n s w ere b ased o n a su p p o sed ad u lt m e n tal age o f sixteen, even th o u g h few o f th e recru its had a tte n d e d school past th e age o f fo u rte en . M any critics also p o in te d o u t th a t test scores o f im m ig ra n t g roups w ere higher th e longer th e g ro u p s h ad been in th is co untry, in d ic atin g th a t m u c h o f th e low scores o f th ese g ro u p s co u ld be a ttrib u te d to an u n fam iliarity w ith A m eric an cu ltu re. B righam h ad ta k en these d a ta to m ean th a t recent im m ig ra n t g ro u p s w ere in n a tely less in tellig en t th a n ea rlier ones. In co n tra st to tho se b o th in an d o u t o f th e psychological c o m m u n ity

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w ho a tta c k e d th e A rm y te sts a n d th e ir in te rp re ta tio n s , Y erkes h im s e lf w rote th e forew ord to B rig h am ’s b ook, n o tin g th a t “ [t]he a u th o r p resen ts n o t th e o ries o r o p in io n b u t fact.”43 M oreover, m a n y early psychologists w ere ce rtain ly a m e n a b le to th e idea o f in n a te differences in intelligence betw een racial a n d so c io -e c o n o m ic groups. W hile n o t co n v in ced by th e A rm y d ata, T erm a n w arn ed in 1922 th a t “ N o n a tio n ca n afford to overlook th e d an g e r th a t th e average q u a lity o f its g erm plasm m ay g rad u ally d e te rio ­ rate as a resu lt o f u n re stric te d im m ig ratio n .”44 H e also arg u ed , in discussing th e resu lts o f th e o rig in a l s ta n d a rd iz a tio n te sts o f th e S ta n fo rd -B in e t, “ [t]h a t the ch ild ren o f th e su p e rio r social classes m ak e a b e tte r show ing in th e tests is p ro b ab ly due, fo r th e m o st p a rt, to a su p e rio r o rig in al en d o w ­ m e n t.”45 R e g ard in g racial differen ces, T e rm a n h y p o th e siz e d th a t w h en p ro p e r ex p e rim en ts o n A m eric an In d ian , M exican , a n d N egro in telligence w ere c o n d u c te d “ th e re will be discovered en o rm o u sly significant racial differences in general intelligence, differences w hich c a n n o t be w iped o u t by an y sch em e o f m e n ta l cu ltu re.”46 T h e lo u d e st p o p u la r voice raised again st th e m e n ta l te stin g m o v e m en t w as th a t o f W alter L ip p m a n n . In a series o f articles in th e N e w R ep u b lic in 1922 a n d 1923, L ip p m a n n p resen ted w h at th e N e w R ep u b lic e d ito rs called a n “ analysis a n d e stim a te o f intelligence tests.”47 L ip p m a n n ’s p rim a ry ta r­ get w as th e idea th a t intelligence tests w ere m easu res o f in n a te m e n tal ability, o r o f “ in tellig en ce” for th a t m atter. H e believed th a t th is id ea was bein g sold to th e p u b lic by elitists (w hat he called th e “ N ew S n o b b ery ” ) atte m p tin g to m a in ta in th e sta tu s q u o (th en , as now, te st scores are higher in th e u p p e r classes), an d by p o w e r-h u n g ry psychologists w ho, w ith o ne ex a m in a tio n , w ould be able to asce rta in a c h ild ’s im m u ta b le m e n tal c a p ac­ ities. T h e N e w R ep u b lic p u b lish ed a reply to L ip p m a n n by T erm an , w ho, th o u g h su rprisingly sarcastic in to n e, w as reaso n ab le in su b stan ce. H e ex ­ p la in ed th a t n o psychologist believed th e tests to be p u re m easu res o f m e n ta l ability (th o u g h to be sure genes w ere th e m o st im p o rta n t factor), a n d th a t w hile ce rta in ly n o t perfect, intelligence tests w ere q u ite useful in d o in g th e k in d s o f things o n e w ould expect an in telligence te st to do. O n e d o u b ts, however, th a t T e rm a n ’s m e a n -sp irite d n e ss (in resp o n se to L ip p ­ m a n n ’s suggestion th a t e n v iro n m e n ta l influences early in life m ig h t have a significant effect o n intelligence, T erm a n pro p o sed th a t L ip p m a n n begin an investig atio n o f th e IQ effects o f “d ifferent versions o f M o th e r G o o se ” )48 d id h im m u ch good in th e p u b lic rela tio n s war. T h e wave o f p u b lic d eb a te set off by th e A rm y d a ta e n d e d by th e m id 1920s, b u t th e issues ad d ressed — h ered ity vs. e n v iro n m e n t, th e n a tu re o f in tellig en ce, a n d th e p ro p e r uses o f te stin g — have re m a in e d im p o r ta n t w ith in professional circles, an d , d u rin g th e past tw en ty -fiv e years, have again en tered th e p u b lic consciousness.

Introduction: The IQ Controversy in Perspective

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As p u b lic attac k s on m e n tal tests w ere subsiding, th e te stin g m o v e m en t was evolving from a largely ex p e rim en tal en terp rise in to a w ell-estab lish ed professional endeavor. T h e 1920s an d 30s saw a p ro liferatio n o f in te l­ ligence a n d specific a p titu d e tests. T erm an p u blished his first revision o f th e S ta n fo rd -B in e t, invo lv in g a sta n d a rd iz a tio n sam ple o f over 3,000 ad u lts an d ch ild ren , in 1937.49 Two years later, D avid W echsler p u b lish ed his first intelligence test, w hich w as to becom e th e W echsler A d u lt Intelligence Scale, th e m o st w idely used in d iv id u a lly -a d m in is te re d intelligence test for a d u lts.50 T h is p erio d w as also n o ta b le for th e d ev e lo p m e n t o f so p h isticated statistical te ch n iq u e s for d e te rm in in g th e reliability a n d validity o f tests, th e in tro d u c tio n o f m a c h in e -s c o rin g te ch n iq u e s, an d th e first larg e-scale a d o p tio n an d tw in studies for system atically investig atin g th e relative roles o f h ered ity a n d e n v iro n m e n t in intelligence. A dditionally, several jo u rn a ls a n d p ro fe ssio n a l o rg a n iz a tio n s d ev o ted to p sych o lo g ical m e a su re m e n t w ere fou n d ed , as w ere n u m e ro u s te st-p u b lish in g firm s d ed icated to th e d ev e lo p m e n t a n d d issem in a tio n o f psychological tests (by 1936 th ere were at least 96 different firm s p u b lish in g tests).51 As a resu lt o f th is increasin g p ro fessio n alizatio n , a general declin e in D arw in ia n e x p lan a tio n s o f b e­ havioral p h e n o m e n a , an d p erh a p s also because o f th e ir ea rlier ex p erien ces in th e pu b lic d o m a in , tho se w ho developed a n d stu d ied intelligence tests b ec am e less bold in th e ir p ro c la m a tio n s a b o u t in n a te m e n ta l ab ility an d th e sources o f g ro u p differences in IQ. E ven B righam a d m itte d in 1930 th a t o n e can m ak e no stro n g claim s a b o u t gro u p differences in in tellig en ce.52 T h e p ublic seem ed to pay little a tte n tio n to an y o f th ese d ev elo p m en ts, ex cept in so far as th ey fo u n d tests beco m in g an increasingly c o m m o n p a rt o f th e ir lives. World War II and the Awakening o f Public C onsciousness T h e p o te n tia l d e m o n stra te d by th e A rm y tests o f W orld W ar I w as real­ ized d u rin g th e S econd W orld War, w hen th e U .S. a rm e d forces engaged in a m assive testin g program . M ore th a n 9 m illion rec ru its to o k th e A rm y G en e ra l C lassification Test (A G C T), a test o f general a p titu d e th a t, in te r­ estingly, th e new breed o f A rm y testers w as very careful n o t to call an in te llig en ce test. U n lik e th e A rm y A lp h a a n d B eta, th e A G C T clearly played an im p o rta n t role in selection a n d classification. M oreover, specific a p titu d e tests, like those given by th e A ir F orce to screen p o te n tia l pilots, p roved to be tre m e n d o u sly useful in fu n n elin g th o se m o st q u alified in to expensive a n d tim e -c o n s u m in g tra in in g p ro g ra m s.53 As in W orld W ar I, th e general p erc ep tio n , p erh a p s m o re a c cu rate follow ing th e S econd W orld War, w as th a t th e testin g estab lish m e n t h ad d e m o n stra te d th a t tests o f m e n tal ability w ere efficient d e c isio n -m a k in g tools.

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A fter th e war, th e grow th o f testin g c o n tin u e d a t a rap id pace. In th e schools, intelligence tests b ecam e a regular p a rt o f th e c u rric u lu m , w here th ey w ere used to segregate stu d e n ts by ability a n d for ed u c atio n al an d career g uidance. In a 1949 artic le in th e N ew York T im e s M a g a zin e, B en­ ja m in F in e estim a ted th a t 20 m illion sch o o lch ild re n w ould be ta k in g in te l­ ligence tests d u rin g th e u p co m in g school year.54 In college ad m issio n s, th e SAT (in tro d u c e d in 1926 a n d req u ired by on ly a sm all fractio n o f colleges a n d universities b efore th e w ar) w as ad o p ted , alo n g w ith th e ACT, by nearly every school in th e n atio n . D u rin g th e w ar years, th e C EEB , sp o n so rs o f th e SAT, d ro p p e d th e ir ea rlier essay -ty p e a c h ie v em e n t te st to c o n c e n tra te on th e m u ltip le -c h o ic e SAT. T h e SAT w as in te n d e d to be less d e p e n d e n t on an y fixed c u rric u lu m th a n an a c h ie v em e n t test, a n d th u s m o re eq u itab le. P erhaps th e largest effect o f th e w artim e testin g p ro g ra m w as felt in e m p lo y m e n t. Surveys o f A m erican in d u stry by W alter D ill S co tt fo u n d th a t th e percen tag e o f c o m p an ie s using intelligence tests for h irin g a n d p ro m o tio n in creased from 26 p erc en t in 1940 to 63 p e rc e n t in 1957.55 T h e g o v ern m e n t helped, as th e new ly fo u n d ed U n ite d S tates E m p lo y m e n t Serv­ ice m a d e tests available at n o cost to em ployers, a n d w ould even dev elo p a n d sta n d ard iz e special tests in re tu rn for d a ta su p p lied to th e g o v ern m en t. T h e e n larg em e n t o f intelligence a n d a p titu d e te stin g in em p lo y m e n t after th e w ar follow ed a d eclin e in such testin g d u rin g th e 1920s a n d 1930s. In d u strial leaders o f th e first p a r t o f th e c e n tu ry h ad failed to heed th e w arn in g s o f im p ro p e r v alid atio n , a n d q uickly fo u n d th a t th e ir u n v alid ated tests w eren ’t w orking. T h e H aw th o rn e W orks p ro jec t o f th e late 1920s, th e first la rg e -scale so c ial-sc ien c e stu d y o f in d u stria l pro d u ctiv ity , co n firm ed w h at em ployers w ere b eg in n in g to realize: th a t m o tiv a tio n a l a n d social factors are as im p o rta n t to c e rta in k in d s o f p ro d u ctiv ity as is ab ility or e x tern al incentives. M ilita ry testin g d u rin g th e S eco n d W orld W ar o n ce again co n v in ced em ployers o f th e usefulness o f intelligence a n d a p titu d e tests. Ironically, th e re en su ed a n o th e r p ro liferatio n o f co m m ercially avail­ able em p lo y m e n t tests, an d o v eren th u siasm a b o u t test use o n th e p a r t o f b o th em p lo y ers a n d te st m a k ers. As before, m a n y in th e te stin g field w arn ed th a t e m p lo y m e n t tests w ere being o verused .56 T h e original p ro m ise o f intelligence tests was as a to o l for in creased efficiency in ed u c a tio n a n d em p lo y m e n t. In th e p o stw ar e n v iro n m e n t, tests held o u t a new hope: th e m e an s for achieving a m o re d e m o c ra tic society th ro u g h th e u n b iased search for ability. Tests b ecam e a to o l for ach iev in g a social o rd e r based n o t o n privilege o r w ealth, b u t on m e rit an d ability.57 D u rin g W orld W ar I, th e validity o f th e tests w as co n firm e d by th e fact th a t officers, w ho w ere “ obv io u sly ” m o re in telligent, o u tsc o re d en listed m e n on th e A rm y tests. B ut th e A m eric an m o o d h ad sh ifted by th e en d o f W orld W ar II, an d th e em p h asis o n m e rit coexisted u neasily w ith a grow ing c o n ­

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sensus am o n g b o th th e pu b lic a n d professionals th a t ability was eq u ally d istrib u te d am o n g all g ro u p s a n d social classes. It is n o t su rp risin g , in th e era o f B row n v. th e B o a rd o f E d u c a tio n , th a t a 1956 poll o f A m eric an a ttitu d e s to w ard d eseg reg atio n fo u n d th a t a lm o st 80 p e rc e n t o f w h ite A m eric an s believed blacks to be th e ir in te lle ctu al equals, co m p ared to o nly h a lf as m a n y w ho believed th e sam e th in g in 1942.58 T h e c o n tra d ic tio n betw een th e new view a n d th e reality o f g ro u p differences in test scores was resolved by th e assu m p tio n th a t, as racial d isc rim in a tio n declin ed , m in o r­ ity g roups w ould o b ta in scores on vario u s m easu res o f intelligence an d ach ie v em e n t eq u al to th o se o f o th e r groups. T h u s, in tellig en ce tests w ere p erceived as progressive in stru m e n ts fo r help in g th e u n d erp riv ileg ed to th e ir rightful place. T h e 1949 N ew York T im e s M a g a zin e artic le by F in e is in stru c tiv e as a b a ro m e te r o f th e p o p u la r m o o d tow ard intelligence testing. E n titled “ M o re a n d M ore, th e IQ Idea Is Q u e stio n e d ,” it is a rare (for th e tim e) p o p u la r c ritiq u e o f testing, an d a n excellent ex am p le o f th e ex cep tio n p ro v in g th e rule. F in e w as w orried a b o u t ov errelian ce o n intelligence te st scores a t th e expense o f m o tiv a tio n a l variables in p red ic tin g stu d e n t p erfo rm an ce . Fie says o f IQ tests, “ Today . . . it is im possible to exaggerate th e ir c o n tin u e d influence o n A m eric an te ac h in g m ethods.” 59 A fter citin g n u m e ro u s in ­ stances o f stu d e n ts o u tp e rfo rm in g th e ir IQs, a n d ex h o rtin g ed u c ato rs n o t to p u t to o m u c h faith in im p erfect in stru m e n ts. F in e ’s d am ag in g c o n ­ clu sio n is: “ In th e classroom a p u p il’s capacity for le arn in g , even if gauged o nly approxim ately , is one o f th e m o st im p o rta n t facts we can know a b o u t h im a n d if IQ tests show a te a c h e r w h at to expect in classro o m p erfo r­ m a n ce th e n they have a definite validity. O nly at all tim es we m u st re­ m e m b e r th a t they c a n n o t be relied u p o n exclusively.”60 A cc o m p an y in g th e generally favorable a ttitu d e s to w ard intelligence te st­ ing o f th e postw ar p u b lic w as a lack o f c o n c e rn for th e g ro u p difference issue, a subject th a t had b een so im p o rta n t in ea rlier p u b lic d eb ate a b o u t testing, an d w ould be again. T h e only m e n tio n o f g ro u p differences in intelligence in th e F ine article is a discussion o f a tte m p ts by U n iv ersity o f C h ica g o so c io lo g ist A llison D avis to d ev e lo p m o re c u ltu r e - f a ir tests. R a th e r th a n attac k in g intelligence tests as biased. F ine m e n tio n s D avis’ w ork m erely as an in d ic a tio n th a t o th e r factors besides n ativ e m e n tal ab il­ ity can affect a y o u n g ster’s score. (In th e p rofessio n al co m m u n ity , D avis’ w ork, like th a t o f m a n y o th e rs w ho a tte m p te d to dev elo p c u ltu re -fre e or c u ltu re -fa ir tests, was generally seen as a noble b u t failed a tte m p t— he was n ev er able to develop a test th a t significantly red u ced so c io eco n o m ic d if­ ferences in test score b u t w as still p redictive o f acad em ic success.) F u rth e r evidence th a t gro u p differences in intelligence w ere n o t a signifi­ c a n t p u b lic issue is the lack o f p u b lic rea ctio n to th e article “ Psychological

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The IQ Controversy

T ests-A S cien tist’s R e p o rt o n R ace D ifferences” in U.S. N ew s a n d W orld R ep o rt in 1956.61 V illanova psychology professo r F ra n k M c G u rk arg u ed th a t th e significant b la c k -w h ite IQ difference a p p a re n t in th e A rm y tests o f W orld W ar I h ad n o t d ecreased a t all d u rin g th e follow ing fo rty years, d esp ite vast im p ro v e m e n t in th e social a n d e c o n o m ic c o n d itio n s o f black A m ericans. H is co n c lu sio n w as th a t th e IQ difference co u ld n o t be a t­ trib u te d to in fe rio r black e n v iro n m e n t. U n lik e th e public, th e professional c o m m u n ity was n o t w illing to ignore such sta te m en ts. A m o n th afte r th e M c G u rk piece, U.S. N ew s ran a tw o page sta te m e n t signed by eighteen social scientists in w hich th ey d en ied th a t th e re was sufficient scientific evidence to ju stify th e co n c lu sio n o f significant genetic g ro u p differences in intelligen ce.62 W hile th e re ce rtain ly w as n o sh o rtag e o f scientific investigations o f th e g ro u p differences p ro b le m — A ud rey S hu ey ’s 1958 T h e T esting o f N egro In tellig en ce review ed over 2 00 such stu d ies— p u b lic sta te m e n ts a b o u t genetic g ro u p differences w ere m e t w ith sh a rp critical rea ctio n fro m th e professio n al co m m u n ity . T h e atro c itie s c o m m itte d in th e n a m e o f th e N azi eugenic policies assu red th a t an y ta lk o f genetic g ro u p differences w as ta b o o . In a d d itio n to M c G u rk , H e n ry G a r re tt’s d escrip tio n o f th e prevailing s e n tim e n t regarding g ro u p differences as “eq u a lita ria n d o g m a ” w as m e t w ith p u b lic cen su re by th e SPSSI.63 A udrey S huey w as u n ab le to get a m a jo r scientific p u b lish in g firm to ac cep t h er b ook, w hich c o n c lu d e d th a t th e re was a significant genetic c o m p o n e n t to b la c k -w h ite IQ differences, a n d had to have it p rin te d p ri­ vately.64 Sim ilarly, w hen U n iv ersity o f C hicago physiologist D w ight Ingle criticized fellow scientists for ig noring th e possibility o f g en etic racial dif­ ferences in intelligence in a 1964 S cience m ag azin e article, su b se q u en t issues c o n ta in e d a host o f hostile replies.65 T h e ac rim o n io u s n a tu re o f p rofessional d e b a te o n th is to p ic w en t v irtu a lly u n n o tic e d by a p u b lic g enerally pleased w ith c u rre n t testing practices a n d o u tco m es. T h in g s began to change d u rin g th e late 1950s a n d early 1960s, as th ree tre n d s converged to a lte r p erc ep tio n s a b o u t intellig en ce testing. T h e first w as a shift in focus in th e psychological co m m u n ity , p a rtic u la rly in d e ­ v elo p m en tal psychology. T h e increasingly p o p u la r w ork o f Je a n P iaget an d his follow ers w as placing th e em p h asis in th e grow th o f co g nitive stru ctu re s o n th e ch ild ’s in te ra c tio n w ith his en v iro n m e n t. M o re a n d m o re, psy ch o l­ ogists ca m e to u n d e rsta n d th a t it was n o t a q u estio n o f n a tu re vs. n u rtu re , b u t n a tu re a n d n u rtu re interactin g . A ch ild ’s intelligence, w h ate v er its g enetic co m p o n e n t, co u ld be significantly en ric h ed o r im p o v erish ed by th e e n v iro n m e n t. T h e m a jo r trea tise o f th is new p h ilo so p h y w as th e 1961 b o o k In telligence a n d E xp erien ce by U niversity o f Illin o is psychologist J. McV. H u n t. H u n t p rese n ted a g reat deal o f evidence to s u p p o rt his p o sitio n th a t in telligence was alm o st infinitely plastic. H u n t’s b o o k , an d th e ideas it

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rep resen ted , w ere e n o rm o u sly influential in b o th the scientific c o m m u n ity an d p ublic policy circles, w here, along w ith B e n ja m in B lo o m ’s 1964 S ta ­ b ility a n d C hange in H u m a n C haracteristics, it p ro v id ed th e scientific ju stifica tio n for th e H ead S tart program . T h e sto ry o f th e beginnings o f H ead S tart is an excellent ex am p le o f how science m ay be u su rp ed for p olitical purposes. T h e original m o tiv a tio n for H ea d S ta rt grew o u t o f th e in creasing e n v iro n m e n ta lism in b o th th e psy­ chological c o m m u n ity a n d p olitical circles, a n d the co n se q u e n t b elief th a t p o verty co u ld be e lim in a te d th ro u g h e d u c atio n . T h e fo u n d ers o f th e H ea d S ta rt pro g ram saw it as a lo n g -te rm social pro g ram aim ed a t m a n y ele­ m e n ts o f the ch ild ’s en v iro n m e n t, in c lu d in g the fam ily a n d c o m m u n ity as m u c h as the classroom . W hen th e pro g ram w as sold to th e p u b lic a n d th e p o licym akers, however, th e politically m o re p alatab le q u ic k fix w as e m p h a ­ sized: tw o m o n th s in a special su m m e r pro g ram w ould significantly raise th e IQs o f u nderprivileged c h ild re n .66 T h e p o sitio n th a t th e e n v iro n m e n t can significantly affect intelligence, even w here genetic factors are im p o rta n t, is o n e w ith w hich few social scientists w ould argue. B ut th e new wave o f th e early 60s in v o lv ed m o re th a n a m ere em p h asis on th e en v iro n m e n t. S om ew here along th e way gen etic factors w ere ignored. T h e lo n g -sta n d in g psychological co n sen su s th a t genes play a large role in w ith in -g ro u p differences in intelligence had b ro k e n dow n. N o o n e seem ed to be den y in g o u trig h t th a t genes are im p o r­ ta n t to intelligence, b u t th e re w as alm o st a con sp iracy o f silence a b o u t th e su b ject as psychologists an d ed u c ato rs b ecam e th e th a n k fu l recip ien ts o f m illio n s o f d o llars o f federal g ra n t m oney aim ed a t raising th e IQ s o f th e un derprivileged. T h e second im p o rta n t tre n d o f th e era involved th e p u b lic as m u c h as th e professionals. P erhaps in ev itab le in light o f th e tre m e n d o u s en th u sia sm w ith w hich A m erica em b ra ce d testin g afte r W orld W ar II, th e 1960s saw a grow ing d ise n c h a n tm e n t w ith intelligence tests as to o ls for ach iev in g a m o re d em o cratic society. P o p u lar b o oks a n d articles beg an ap p e arin g in w hich tests w ere criticized as im p u re m easu res o f intelligence, a n d th e te stin g c o m m u n ity was p o rtra y ed as an a n ti-d e m o c ra tic force w ith u n ­ ju stified pow er over p eo p le’s lives. A dditionally, th e re w ere c o m p la in ts o f o v errelian ce on an d m isin te rp re ta tio n o f test scores. M an y p are n ts an d teachers, in a d eq u a tely tra in e d in p sy chom etrics, su c cu m b ed to th e m agic o f th e IQ , a n d th e b elief th a t a single test score co u ld tell th e m m o st o f w hat th ey need ed to know a b o u t a ch ild ’s ability to succeed. In a way, th e in creas­ ing c o m p la in ts a b o u t testin g w ere m erely an ex ten sio n o f B en jam in F in e ’s ea rlier w arnings, b u t now th e p ublic seem ed m o re in c lin e d to listen. In 1949, th e tests rep resen ted th e ro ad to the good life; by th e 1960s, it was clear th a t m a n y people nev er got there.

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The IQ Controversy

R e la te d to th e se d e v e lo p m e n ts , o f c o u rs e , w as a g ro w in g p u b lic aw areness o f in e q u ity in A m eric an society, a n d th e will to d o so m e th in g a b o u t it. T h e civil rights m o v e m en t aw akened p u b lic co n scio u sn ess to th e d ep lo ra b le social a n d e c o n o m ic circ u m sta n ce s o f m a n y m in o rity groups, a n d eq u a lity b ecam e th e w atchw ord. M an y o f th e in e q u itie s a p p a re n t in e d u c a tio n a n d e m p lo y m e n t, like d is p ro p o rtio n a te b lack e n ro llm e n t in E M R classes, involved resources a n d o p p o rtu n itie s in w hich in tellig en ce o r a p titu d e te s tin g p la y ed a n a llo c a tiv e ro le . P e r s is te n t ra c ia l a n d s o ­ c io ec o n o m ic IQ differences co u ld on ly be in te rp re te d as ev id en ce o f th e c u ltu ra l d ep riv a tio n experienced by v arious m in o rity g ro u p s a n d /o r as th e resu lt o f test bias. T h ere w ere, however, d ee p er issues involved. As D an iel Bell has argued in T h e C ultu ra l C ontradictions o f C a p ita lism , liberal cap italist d em o cracy in th e U n ite d States had been b u ilt on n o tio n s o f in d iv id u alism , te m p e re d by c o m m itm e n ts to h ard w ork a n d se lf-re stra in t deriv ed fro m a C alv in ist religious sensibility. Science a n d e n lig h te n m e n t h ad ero d e d th e religious view, w hich defined w ork as a calling, a n d replaced it w ith th e n o tio n o f w ork as so m e th in g th a t w ould lead to ever g rea ter in d iv id u al m ateria l satisfaction. In c o n te m p o ra ry A m erica th e la tte r n o tio n h ad been replaced by th e urge to achieve satisfactio n th ro u g h in d iv id u al se lf-d e v elo p m e n t a n d th e c o n s u m p tio n o f m ean in g fu l experience. T h e u n d e rm in in g o f tra d itio n a l bourgeois sensibilities, in c lu d in g c o m ­ m itm e n ts to s e lf-re stra in t a n d a p p ro p ria te p a tte rn s o f au th o rity . Bell a r­ gues, h ad been en co u rag ed by in tellectu als (b road ly d efin ed ) in b o th E u ­ ro p e a n d A m erica, a n d ab so rb e d by th e professio n al elites em erg in g in ad v a n ce d c a p ita list societies. Bell stresses w h at he calls th e “d isju n c tio n o f realm s." W hile th e te c h n o -e c o n o m ic realm calls for efficiency a n d m er­ ito c ratic hierarchy, th e c u ltu ra l realm was now em p h asizin g th e eq u a lity o f all ex p erien ce.67 To m a n y o f th o se on th e Left, especially, IQ tests a n d even th e n o tio n o f IQ ca m e to be seen as th e very e p ito m e o f a stratified , im p e rso n al, b u ­ rea u cratic, racist society. To a tta c k th e m w as also to m o u n t a c ritiq u e ag a in st th a t society in general. Enter Jensen A sp ark w as ap p lied to th e tin d e r box created by th ese co nverging social tre n d s by A rth u r Je n sen in early 1969. P erh ap s to rch is a b e tte r im age, for Je n sen d id n o t m erely specu late a b o u t ta b o o issues; “ EIow M u ch C a n We B oost IQ a n d S cholastic A ch iev em en t?” w as d irected at th e h e a rt o f th e c u rre n t orthodoxy. T h e artic le begins “C o m p e n sa to ry ed u c a tio n has been trie d a n d it a p p a re n tly has failed.”68 T h ere follow s a 1 2 3 -p ag e review o f th e

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scientific literatu re on th e genetic a n d en v iro n m e n ta l d e te rm in a n ts o f in ­ telligence. A m o n g Je n se n ’s conclusions: the failure o f larg e-scale c o m p e n ­ sa to ry ed u c a tio n p ro g ram s to raise IQ s significantly is best ex p lain ed by th e lim ita tio n s placed o n in tellectu al plasticity by an in d iv id u a l’s genetic e n ­ d o w m en t. Based on th e cu rre n tly available evidence, Je n sen placed th e h eritab ility o f intelligence at a b o u t .80, m e an in g th a t 80 p erc en t o f th e in d iv id u al differences in IQ in th e A m eric an p o p u la tio n co u ld be trac ed to g enetic differences. T h o u g h h ardly belligerent in to n e, Je n sen was, by th e n a tu re o f his sta te m en ts, “girding h im se lf for a holy w ar against ‘en v iro n m e n ta lists,’” as o n e c o m m e n ta to r p u t it.69 C o m in g as th ey d id o n th e heels o f th e W estin g h o u se L e a rn in g C o rp o ra tio n re p o rt, w hich h ad c o n c lu d e d th a t th e p ro m ise d IQ gains from H ea d S ta rt h ad n o t m a teria liz ed ,70 Je n s e n ’s re ­ m ark s w ere n o t likely to sit well w ith th e psychological a n d ed u c atio n al estab lish m en t. M oreover, th o u g h he a d m itte d th a t in telligence is n o t easily m easu red , Je n sen argued for th e validity a n d usefulness o f intelligence tests, a n d was w illing to accept th e tests as m easu res o f intelligence, a view c o u n te r to th e grow ing d isillu sio n m e n t w ith testin g am o n g th e a rtic u la te a n d in fo rm e d public. As m u c h as these sta te m e n ts a b o u t IQ h eritab ility a n d th e valid ity o f tests w ere likely to, a n d in fact did, in cite critical rea ctio n , n o th in g in Jen sen 's article w as nearly as in fla m m a to ry as his sp e cu la tio n s a b o u t th e fifte e n -p o in t b la c k -w h ite IQ difference, a gap th a t has existed for as long as th e re have been useful m easu res o f intelligence. Je n sen fo u n d it “ n o t an u n rea so n ab le h ypo thesis” th a t genetic factors are im p lica te d in th is dif­ ference. A d m ittin g th e re w as insufficient evidence to reach a stro n g c o n ­ c lu sio n . Je n se n n e v e rth e le ss felt th a t th e e x istin g e v id e n c e w as m o re co n siste n t w ith a h ypothesis o f g enetic a n d en v iro n m e n ta l d e te rm in a tio n th a n w ith a strictly en v iro n m e n ta l ex p lan a tio n . T h e v iru le n t rea ctio n to Je n se n ’s article on college ca m p u se s an d in th e p o p u la r press m a rk e d the beginning o f th e m o d e rn IQ controversy. T h e fu ro r over Je n sen to u c h ed off a p ublic d eb ate over intelligence testin g m u c h larger th a n th a t created by th e A rm y tests. T h e o p p o sitio n to testin g th a t h ad been p ro m in e n t afte r W orld W ar I, a n d w hich had begun to surface again d u rin g th e 1960s, cam e fully to th e fore d u rin g th e first h a lf o f th e 70s. Besides th e q u estio n o f g ro u p differences in intelligence, th e issues o f test validity, the heritab ility o f intelligence, an d o f course, c u ltu ra l bias e n tered th e p o p u la r literatu re . T h e 1970s saw a flood o f p o p u la r b o o k s on testing, alm o st all o f w hich w ere critical o f Je n sen a n d o f in telligence tests in general. T h e new s m edia helped to foster p ub lic d eb ate by in creasin g th e ir coverage o f testin g issues. D u rin g th e first h a lf o f th e last decade, n early every g e n e ra l-in te re st m agazine in th e c o u n try h a d at least o ne

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article o n th e IQ controversy, co n c e n tra tin g p rim a rily o n th e racial issue. T h e m a jo r new spapers, like th e N e w York T im e s a n d th e W ashington Post, closely follow ed th e exploits o f th e p rin cip als in th is u n fo ld in g d ram a . A n d th e re w as p le n ty to cover. A m o n g th e m o re p ro m in e n t players w as H a rv a rd psychology p ro fesso r R ich a rd H e rrn ste in . H is e n try in to th e d e b a te is an ex a m p le o f how p u b lic co ntroversies o ften feed u p o n them selves. H e rrn s te in , w h o is n o t a p sy ch o ­ m e tricia n , a n d w ho h ad nev er d o n e an y research o n issues related to in te l­ ligence o r testing, b ec am e in te reste d in th e to p ic th ro u g h a ch a p te r he h ad w ritte n for an in tro d u c to ry tex tb o o k , a n d th ro u g h J e n se n ’s article. H e fo u n d p a rtic u la rly co m p ellin g Je n se n ’s arg u m e n ts a b o u t th e su b stan tia l h eritab ility o f intelligence. H e rrn s te in began to read m a n y o f th e original so urces an d becam e co n v in ce d th a t Je n sen w as co rrec t. H e rrn s te in was also stru ck by th e im p o rta n t role intelligence seem ed to play in ec o n o m ic m o b ility in A m eric an society. In a 1971 A tla n tic artic le en title d “ I.Q .,” H e rrn s te in argued th a t if intelligence is im p o rta n t in th e race to get ah ead , an d if intelligence is largely h eritab le, th e n th e re will be genetic differences b etw een m e m b ers o f d ifferent so c io eco n o m ic classes. H e m ad e no m e n tio n o f th e racial issue, p er se, except to say th a t th e m o st rea so n ab le co n c lu sio n a t p rese n t is th a t we d o n ’t know if genetic facto rs are im p lica te d o r not. N onetheless, blacks are d isp ro p o rtio n a te ly rep rese n ted in th e low er classes, a n d it w as easy to g ro u p H e rrn s te in w ith Je n sen as yet a n o th e r ex a m p le o f a long histo ry o f w hite elitists ready to use te st scores a n d g enetics as ju stific a tio n for an in e q u ita b le social stru ctu re . As w ith Je n sen , th e rea ctio n to H e rrn s te in w as hostile. H is classes w ere regularly d isru p te d , he w as p rev e n ted from sp eak in g a t H arv ard a n d at o th e r cam puses, even w hen he h ad co m e to speak a b o u t issues o th e r th a n testing, a n d he was regularly called a racist. In th e press a n d elsew here, H e rrn s te in ’s n am e b ecam e linked w ith th a t o f Je n sen an d S tan fo rd ph y s­ icist W illiam Shockley. A 1971 A m eric an A n th ro p o lo g ical A sso ciatio n res­ o lu tio n c o n d e m n e d “as d a n g e ro u s an d u nscien tific th e racist, sexist o r a n ti-w o rk in g class th e o ries o f genetic in ferio rity p ro p ag a ted by R. H e rrn s ­ te in , W. S hockley an d A. Je n sen .”71 T h e new s m e d ia w ere fo n d o f d escrib ­ ing th is u n h o ly triu m v ira te as sc ien tists h o ld in g co n tro v e rsia l th e o rie s a b o u t th e in n a te in ferio rity o f blacks. In fact, H e rrn s te in h ad m a d e no claim s a b o u t th e racial issue, a n d Je n sen said n o th in g a b o u t inferiority, o n ly low er intelligence. S hockley w as a d ifferent story. M ore b la ta n tly p o litical th a n Je n sen o r H e rrn s te in , Shockley, a N obel P rize w in n er (as o n e o f th e in v e n to rs o f th e tran sisto r), w as p ro b ab ly m o re responsible th a n an y o n e for giving th o se on th e p ro -te stin g side a b ad n am e. E ven before th e p u b lic a tio n o f J e n s e n ’s article, S hockley h a d been try in g to get th e N a tio n a l A cad em y o f Sciences

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(N A S) to sp o n so r research on g ro u p differences in intelligence. In to n es sm ack in g o f ea rlier eugenicists, S hockley w ould speak o f “dysgenic tren d s" in th e A m eric an p o p u la tio n , an d at o n e p o in t sp ecu lated p u b licly a b o u t paying people n o t to have ch ild ren , th e a m o u n t o f p ay m en t to be d eter­ m in e d by th e in d iv id u a l’s IQ; th e low er th e IQ . th e larger th e in c en tiv e n o t to breed. W hen, in 1980, m illio n a ire in v e n to r R o b e rt G ra h a m sta rted his sp erm b an k for N obel P rize w inners, S hockley was o n e o f th e first to c o n trib u te a n d th e only o n e to a d m it it publicly. As S hockley to u re d th e c o u n try p ro p o u n d in g his views, th e N ew York T im e s pro v id ed b lo w -b y -b lo w coverage o f th e tu m u lt. T h e N A S, w hich for years h ad refused to h o n o r S hockley’s call for research, su rp risin g ly c a p itu ­ lated in 1971, b u t on ly in agreeing th a t racial differences sh o u ld be stu d ied . T h ey declin ed to fu n d such research. Testing Under Attack W hile Jensen's H E R artic le w as th e spark th a t to u c h e d off th e IQ c o n tro ­ versy, it w ould be a m istake to believe th a t th e re w ould have b een no co n troversy w ith o u t it. C riticism o f te stin g w as o n th e rise th ro u g h o u t th e 60s; Je n se n ’s article served to accelerate th e pace an d to focus a tte n tio n on th e racial issue. As early as 1968, how ever, th e A sso c iatio n o f B lack P sychologists h ad called for a co m p lete m o ra to riu m on sta n d ard iz ed te st­ ing, charging th a t th e tests w ere biased a n d w ere b eing used to stigm atize m in o rity ch ild ren . In 1972, th e N E A passed a sim ila r reso lu tio n . T h e co n troversy was, in fact, m u ch b ro a d e r th a n th e th e o ries o f H e rrn ste in , Je n sen , a n d Shockley. M u ch o f the grow ing d isillu sio n m e n t w ith te stin g w as tied to a n o th e r ed u c atio n al m o v e m en t, tow ards m a in strea m in g . M a in strea m in g refers to th e te ac h in g o f h a n d ic a p p e d ch ild ren in th e sam e classro o m w ith th e ir n o n h a n d ic a p p e d peers, ra th e r th a n in se p arate classes, a n d is m a n d a te d by P u b lic Law 9 4 -1 4 2 , th e E d u c a tio n for All H a n d ic a p p e d C h ild re n A ct o f 1975. In th e years p receding th e passage o f 9 4 -1 4 2 , m a n y ed u c ato rs had c o m e in c re a sin g ly to b eliev e th a t te a c h in g h a n d ic a p p e d c h ild re n (re ­ gardless o f th e ty p e o f h an d ica p ) in se p arate classes is stig m atizin g a n d d e trim e n ta l to th e e d u c a tio n a l process. A t th e sam e tim e , as previously m e n tio n e d , th e re w as a very stro n g tre n d away fro m tra c k in g (ab ility g ro u p in g ) a m o n g n o n h a n d ic a p p e d ch ild ren , th e idea b eing th a t all ch ild ren sh o u ld , as m u c h as possible, be given th e sam e ed u c atio n . A large p a rt o f th e p ro b lem w ith tra c k in g a n d o th e r fo rm s o f ed u c atio n al segregation is th a t stu d e n ts fro m c e rta in racial a n d so c io eco n o m ic g ro u p s find th e m ­ selves d isp ro p o rtio n a te ly in th e excluded groups. As a p rim a ry to o l by w h ich trac k in g a n d p la c e m e n t decisions are m ad e, in telligence a n d a p ­

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titu d e tests ca m e u n d e r close scrutiny. T h e L a r r y P. d ecisio n is, o f course, o n e ex am p le o f w here th is e x a m in a tio n led. A m o n g th e n u m e ro u s critiq u es o f intelligence te stin g to a p p e a r d u rin g th is perio d w as a 1974 b ook. T h e S cience a n d Politics o f IQ by P rin c e to n psychologist L eon K am in . L ike H e rrn s te in , K am in h ad n o ex p erien ce w ith testing before th e p u b lic a tio n o f J e n s e n ’s article. Ironically, K am in b ecam e in te reste d in th e to p ic w hen, as c h a irm a n o f th e P rin c e to n p sy ch o l­ ogy d e p a rtm e n t in 1972, he h ad to deal w ith th e fu ro r resu ltin g fro m a sched u led talk by H e rrn s te in . W hen K am in e x a m in e d th e intelligence lite ra tu re for him self, he ca m e to co n c lu sio n s th a t w ere th e o p p o site o f H e rrn s te in ’s. N o t only, K am in decided, h ad th e h isto ry o f testin g been o n e long a tte m p t to keep m in o ritie s an d th e low er classes from u su rp in g th e privileges o f tho se in power, b u t th is p o liticiza tio n o f science in c lu d ed th e d a ta on IQ heritability. K a m in claim ed th a t th e re w as no rea so n ab le evi­ d en c e fo r a n y h eritab le c o m p o n e n t to in d iv id u al differences in IQ. T h is w as a rem a rk a b le assertio n in th a t it flew in th e face o f over fifty years o f research th a t had alm o st u n a n im o u sly c o n c lu d e d th a t IQ h eritab ility was su b stan tia l. It h as been n o te d th a t th is co n sen su s h ad been largely fo rg o t­ te n d u rin g th e e n v iro n m e n ta list d o m in a te d 60s, b u t it h ad n ev er been d irectly d isp u ted . In th e ac rim o n io u s clim a te o f th e 70s, a n y th in g was possible. As a resu lt o f his radical p o sitio n , K a m in often fo u n d h im se lf playing th e p a rt o f th e sp o k e sm an for th e o p p o sitio n in m e d ia ac c o u n ts o f th e d eb ate over IQ heritability. A lthough K a m in rep rese n ted th e m o st ex tre m e p o ssi­ ble p o sitio n o n th e issue, th e p ro d u ce rs o f 6 0 M in u te s a n d o th ers w ere h ap p y to set h im u p o p p o site Je n sen o r H e rrn s te in , giving th e view ing an d re a d in g a u d ie n c e th e im p re ssio n th a t e x p e rts w ere, a t b est, u n d e c id e d a b o u t th e role o f genes in in tellig en ce.72 T h a t Je n sen o r H e rrn s te in w ere o ften ch o sen to rep resen t th e h e re d ita ria n p o sitio n d id n o t help m a tte rs, since th ey h ad alread y been associated w ith racism in ea rlier press rep o rts. T h e d ea th blow fo r th e h e re d ita ria n p o sitio n , from th e m ed ia p ersp ec­ tive, ca m e w ith th e w idely publicized scandal su rro u n d in g S ir C yril B u rt, th e B ritish psychologist w ho, late in life, a p p a re n tly h ad faked d a ta c o n ­ ce rn in g th e h eritab ility o f intelligence. E vid en ce o f B u rt’s deceit began to su rface in 1973 a n d 1974, b u t w as n o t b ro u g h t to th e a tte n tio n o f th e g eneral pu b lic an d th e ac ad e m ic estab lish m e n t as a w hole u n til late 1976, w hen articles in th e T im e s o f L o n d o n a n d S cien ce m a g az in e73 (an d su b se­ q u e n tly th e N e w York T im e s a n d th e rest o f th e A m eric an p rin t m ed ia) review ed th e evid en ce th a t B u rt h ad in v e n ted d a ta fo r tw in stu d ies o f IQ heritability, an d publish ed , u n d e r th e n am es o f fictitio u s au th o rs, p ap ers su p p o rtin g his ow n p o sitio n s a n d attac k in g th o se o f his critics. T h e im m e ­ d ia te r e a c tio n fro m m a n y o f th o s e m o s t c o n c e r n e d a b o u t th e IQ

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h eritab ility issue w as as irra tio n a l as it w as predictab le. F rien d s o f B u rt, a n d o th e r believers in su b stan tia l IQ heritability, saw th e attac k s o n B u rt as a n o th e r ex am p le o f th e sm e ar ta ctics o f left-w in g e n v iro n m e n ta lists o u t to destroy th e e n tire testing estab lish m e n t. E n v iro n m en talists, on th e o th e r h a n d , accepted th e evidence against B u rt as p ro o f th a t th e h ere d itaria n th e o ry o f intelligence was, fro m th e beginning, a co n sp iracy ag ain st m in o r­ ities an d th e p oor.74 T h a t th is m in i-c o n tro v e rsy en d e d w ith L. S. H ea rn shaw ’s careful b iography o f B u rt in 19 7 9,75 in w hich th e a u th o r co n clu d es th a t B u rt m o st likely was guilty o f in te lle ctu al frau d , d id n o t help th e p ro ­ te stin g cause in th e larger d eb a te a b o u t IQ. T h e new s m e d ia covered these ev en ts closely, em p h asizin g th e dam ag e caused to th e h e re d ita ria n p o sitio n by th e loss o f B urt's d ata. To be sure, th e m ed ia w ere generally carefu l to p o in t o u t th a t th ere w ere tho se w ho believed th e loss o f th is d a ta m ad e little difference to th e stren g th o f th e h ere d itaria n claim , b u t th e sp o k esm en for th is positio n w ere usually Je n sen o r H e rrn ste in . The Controversy as a W hole A t th e h e a rt o f th e IQ controversy is a clash betw een tw o sets o f values c e n tra l to A m e ric a n th o u g h t. T h e rela tiv e d o m in a n c e o f th ese valu es th ro u g h o u t the tw en tieth c e n tu ry has largely co n tro lled th e fate o f in te l­ ligence testin g in th is country. As we have alread y p o in te d o u t th is clash closely parallels w h at D aniel Bell has called th e “ d isju n ctio n o f realm s.” T h is d isju n ctio n is reflected in the ratio n al b elief in intelligence a n d a p ­ titu d e tests as efficient to o ls for th e d istrib u tio n o f resources, coexisting w ith a c u ltu ral a n d p olitical o u tc ry again st supposed in d iv id u al a n d gro u p differences in intelligence. T h e IQ controversy rep resen ts a clash o f values, o ften w ithin th e sam e person, betw een a b elief in a m e rito cratic h ierarch y (efficiency) an d th e desire to see everyone succeed (eq u ality ).76 T h e desire for efficiency places the em p h asis on differences betw een in div id u als, w hile eq u a lity c o n c e n tra te s on th e sim ilarities. Efficiency in a co m plex in d u stria l society req u ires th a t resources a n d o p p o rtu n itie s (e d u ­ ca tio n , em p lo y m e n t, pow er) be allocated to tho se w ho will use th e m m o st p roductively, as defined by th e p ro d u c tio n re q u ire m e n ts (m aterial, artistic, scientific, etc.) o f th e society. A m o n g th e skills m o st im p o rta n t to p ro d u c ­ tivity in o u r society is in tellectu al ap titu d e o f vario u s sorts. In a cap italist system , value is placed on these skills th ro u g h v ario u s rew ards (m oney, prestige, etc.), w hich serve as in cen tiv es to assure th a t skills are p ro p ag ated an d resources p ro p erly allo cated th ro u g h c o m p e titio n . B ut th e d istrib u tio n o f rew ards th ro u g h co m p e titio n also ca rrie s w ith it th e n o tio n o f dessert. T h o se w ho receive sought after rew ards are. ideally, th o se w ho m o st deserve th e m , hence th e n o tio n o f th e m eritocracy. B ut ju s t as th e aristocracy,

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o riginally m e an in g “rule by th e best citiz en s,” w as c o rru p te d in to “ ru le by w ealth an d in h e rita n c e ,” so m ay “ rule by th e m o st d eserv in g ” (read “ best citizens” ) c o n ta in th e seeds o f elitism a n d racism . In tellig en ce an d a p titu d e tests m ay in fact be useful too ls fo r th e a c h ie v em e n t o f an efficient a n d p ro d u ctiv e society, b u t th e system they help p ro p ag a te ca rrie s w ith it th e d an g e r o f an en tre n c h e d elite w ho can p erv e rt th ese to o ls to m a in ta in a n o tio n o f th e ir ow n in h e re n t superiority. T h e eg alitarian ideal is th e an tith e sis o f elitism a n d racism , a n d th e su b ju g atio n o f in d iv id u als a n d g ro u p s resu ltin g th e re fro m . T h e d e m o cratic ideal th a t all m en are created eq u al req u ires th a t u n d e r a cap italist system th e co m p e titio n be fair an d th a t resources be allo cated to th o se m o st d e­ serving (to th o se w ho possess th e necessary a ttrib u te s an d skills), irre sp e c­ tive o f race, religion, ethnicity, w ealth, a n d o th e r facto rs th o u g h t to be irre le v an t to o p tim u m resource u tiliza tio n . (P ro p o n e n ts o f affirm ativ e ac­ tio n an d o th e r q u o ta system s argue th a t society will a c tu a lly fu n ctio n m o re sm o o th ly if so m e o f these factors are ta k e n explicitly in to a c c o u n t in o rd er to c o rre c t past inequities.) T h e d an g e r in h e re n t in eg alitarian ism is th a t a p h ilo so p h y o f h u m a n rights m ay be e x tra p o lated in to a th e o ry o f h u m a n n atu re . T h a t in d iv id u als sh o u ld be tre a te d equally does n o t m e an th a t all in d iv id u als are equal. W h e th e r as a resu lt o f ac cid en ts o f b irth a n d e n ­ v iro n m e n t, o r th ro u g h stren g th o f will, people differ in ab ilities o f all sorts, an d it is possible th a t these abilities are n o t eq u ally d istrib u te d a m o n g all p ossible su bgroups o f the p o p u la tio n . Yet in a system w here th e re is m e rit a tta c h e d to c e rta in a ttrib u tes, regardless o f th e ir origin, in e q u ity is easily perceived, even in situ a tio n s w here c o m p e titio n is fair a n d objective. W h en tests tell us th a t in d iv id u als a n d g roups differ in average in tellectu al ability, th e re is a te n d en c y to b la m e th e m essenger a n d cry “ con sp iracy ,” ra th e r th a n accept w h at m ay be an u n p le a sa n t fact. T h e te n d en c y tow ard a p p a r­ en tly irra tio n a l response (if th a t is w h at m u c h criticism o f testin g is) is h eig h ten ed by th e a p p a re n t racism an d elitism (if th a t is w h at tra d itio n a l p ro -te s tin g views are) o f th o se w ho m a in ta in th a t in tellig en ce tests m e a ­ sure im p o rta n t a ttrib u te s o n w hich indiv id u als, a n d possibly groups, differ genetically. It m ight be argued th a t th e d ic h o to m y here o u tlin e d is u n d e rm in e d by th e fact th a t th e m e rito crac y is an egalitarian ideal, to be c o n tra ste d w ith th e elitist aristocracy. T h is w as tru e in th e years follow ing W orld W ar II, w hen tests w ere p ro cla im e d as tools for achiev in g a m e rito c ra tic o rd er based on fair co m p e titio n betw een m e m b ers o f all gro u p s. O n e o f th e p ro d u c ts o f th e civil rights m o v e m en t w as a red efin itio n o f fair c o m p e ti­ tio n . F airness ca m e to be defined in te rm s o f o u tc o m es (eq u al rep rese n ta­ tio n ) ra th e r th a n processes (equal o p p o rtu n ity ). N o t all o f th o se w ho had su p p o rte d th e tra d itio n a l m e rito cratic n o tio n s w ere w illing to acq u iesce in th is change (p artic u larly th o se w ho h ad benefited from th e system ), h en ce

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th e conflict betw een m e rito crac y an d eg alitarian ism . T h e te rm s are ours; n o d o u b t te s tin g 's s u p p o r te r s w o u ld n o t c o n s id e r th e m s e lv e s n o n ­ eg alitarian, n o r w ould its critics call th em selves a n ti-m e rito c ra tic . T h e IQ co n troversy is n o t d riven by th e conflict betw een perso n s, however, b u t by th e conflict betw een tw o essentially d e m o c ra tic ideals. O n e can see, in th e h isto ry o f th e IQ controversy prev io u sly o u tlin ed , th e im p e tu s o f factors favoring th e relative d o m in a n c e o f o n e o r th e o th e r o f these views. A t th e tu rn o f th e century, a n d th ro u g h th e F irst W orld War, th e need to organize th e chaos created by in creasin g in d u stria liz a tio n , th e grow th o f p u b lic ed u c atio n , a n d th e rap id influx o f m y riad im m ig ra n t g ro u p s placed th e em p h asis squarely o n efficiency, role sp ecializatio n , an d th e id en tificatio n o f in d iv id u al differences. T h e use an d p o p u la rity o f in te l­ ligence a n d a p titu d e tests increased rapidly, often m o re rap id ly th a n th e validity o f th e tests w arra n te d . A t the sam e tim e, th e excesses o f th e m er­ ito c ratic ethos, co u p led w ith x e n o p h o b ia tow ard im m ig ra n t g roups a n d a long h isto ry o f racism , led to th e b a sta rd iz a tio n o f th e W orld W ar I A rm y testin g results. T h e en su in g IQ controversy rep rese n ts th e first eg alitarian b acklash. Betw een th e w ars, as eugenic a n d x en o p h o b ic a ttitu d e s w aned, m e n tal testers b ecam e m o re professional, th e view of tests as to o ls o f efficiency c o n tin u e d to ho ld th e u p p er h a n d , a n d few c o m p la in ts a b o u t testin g w ere h eard. T h e eg alitarian ethic, on th e rise after W orld W ar II, em b ra ce d th e new ly refu rb ish ed tests as m ean s for a m o re eq u itab le d istrib u tio n o f re­ sources, a n d sta n d ard iz ed testin g enjoyed its greatest p o p u larity . T h e love affair w as sh o rt lived, however, as eg a litarian ism b lo sso m ed in to th e civil rights m o v em en t, a n d a heavily e n v iro n m e n ta list view o f h u m a n n atu re . Je n sen , H e rrn s te in , a n d Shockley pro v id ed fo d d er for grow ing c o n sp ir­ ato rial th eo ries o f th e testin g en terp rise, a n d a new, m o re pervasive IQ co n troversy em erged. In recen t years, th e en em ies o f te stin g have gain ed im p o rta n t g ro u n d in th is ongoing war. It is th e p u rp o se o f th is b o o k to e x a m in e m o re closely th e im p o rta n t c o m b a ta n ts a n d battlefields in th e w ar over testing. M o st o f th e fighting has ta k en place on tw o fronts: in th e new s m edia, a n d in p u b lic policy aren as. We have discussed how th o se o p posed to testin g a p p e a r to have m ad e co nsid erab le gains in b o th d o m a in s. T h is m ay o r m ay n o t be for th e best. W h a t is u n fo rtu n a te a b o u t th e p u b lic controversy over in telligence an d a p titu d e testin g is th a t it is so often u n in fo rm e d . M u c h o f th e relev an t d iscussion an d decision m a k in g seem s m o re influen ced by p o litical co n sid ­ e ra tio n s th a n by th e em p irical lite ra tu re on intelligence an d testing. T h e recen t h isto ry o f th is contro v ersy is m a rk e d by th e in creasin g su b su m p tio n o f w h at is p rim a rily a te ch n ic al issue, th e validity a n d usefulness o f in te l­ ligence a n d ap titu d e tests, u n d e r p olitical con cern s. Tests are an im p o rta n t p u b lic policy issue, as th ey c o n tin u e to play a

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m a jo r allocative role in ed u c a tio n an d em p lo y m e n t. T h e ir p o liticiza tio n is th e re fo re to so m e degree desirable; in a p a rtic ip a to ry dem ocracy, citizens sh o u ld have a say in how resources are d istrib u ted . D ifficulties arise w hen th is p o liticiza tio n so overw helm s th e te ch n ic al issues th a t it is fo rg o tten th a t m o st m e m b ers o f society, in c lu d in g m o st o f th o se ch arg ed w ith policy d ecisions, are ill eq u ip p ed to deal w ith th e te ch n ic al q u e stio n s involved. W h a t has h ap p e n ed in th e IQ contro v ersy is th a t th e ex p e rt voice has been m isin te rp rete d an d m isrep resen ted , as science has been p erv erted for p o lit­ ical ends. (T h e decision to use intelligence tests is a policy, an d th erefo re p olitical, decision, in w hich th e te ch n ic al q u estio n o f t e s t v alidity sh o u ld play an im p o rta n t, b u t n o t necessarily decisive, p a rt. T h e q u e stio n o f test validity, o r test bias, on th e o th e r h an d , is a p u rely te ch n ic al o n e, a n d sh o u ld n o t be influenced by political co n sid eratio n s.) T h e new s m ed ia have, o f course, always ap p ealed to ex p e rts in th e ir coverage o f controversies, b u t th e te n d en c y in th e m e d ia is to p a in t every­ th in g in black a n d w hite, as if ex p erts are equally split betw een tw o d i­ am etric ally o p p o site positions. We have n o te d th is te n d e n c y regarding th e IQ h eritab ility q u estio n . F u rth e rm o re , th e re is reaso n to believe th a t th e m ed ia m ay have alread y decid ed w hat th e ex p e rts th in k c o n c e rn in g IQ. W h en T im e m ag azin e tells us, as it did in 1977, th a t “th e m o re tests th a t are devised, th e m o re ed u c ato rs seem to d o u b t th e ir validity,’’77 we are led to believe th a t tho se w ho publicly a tta c k tests are ech o in g th o se m o st know ledgeable a b o u t th em . F lerrn stein has n o te d th a t every review o f a b o o k c o n c e rn in g intelligence testin g in th e N ew York T im e s B o o k R ev iew betw een 1975 a n d 1981 is critical o f testing, a n d th a t n o n e o f th e review ers is a tra in e d p sy c h o m e tric ia n .78 In th e legislatures a n d in th e co u rts, ex p ertise o ften tak es a back seat to p o litical co n sid eratio n s. T h e difficulties here are sim ila r to th o se in th e new s m edia. A s in th e m edia, w here co n tro v ersy is p rese n ted as a clash betw een p o la r opposites, th e ad v ersary system , as p racticed in legislative h earings an d , to a g rea ter ex ten t, th e co u rts, is n o t co n d u c iv e to th e a c ­ q u isitio n o f em p irica l know ledge. R a th e r th a n being p resen ted w ith an o b je c tiv e a s se ss m e n t o f th e lite ra tu re , le g isla to rs a n d ju d g e s h e a r th e stro n g est possible case for w h at are often th e m o st ex tre m e a rg u m e n ts in a d eb ate. Faced on ly w ith o p tio n s at th e extrem es, d ecision m ak ers m u st e ith e r a d o p t an ex tre m e p o sitio n o r d evelop o n e o f th e ir ow n. U n fo r­ tu nately, such decisions are o ften o u t o f synch w ith th e facts. C onsider, fo r exam ple, th e decisions reach ed by Ju d g e P eck h am in th e L a r r y P. case, a n d by a n o th e r federal d istric t c o u rt ju d g e, Jo h n G rady, in a highly sim ila r case in 1980 (P A S E v. Hannon).™ As in L a r r y P., Ju d g e G ra d y was asked to en jo in th e use o f intelligence tests for th e p la ce m en t o f black ch ild ren in to special ed u c a tio n classes becau se th ese tests are racially

Introduction: The IQ Controversy in Perspective

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biased. R em arkably, Ju d g e G ra d y ’s decision w as exactly th e o p p o site o f th a t reached by Judge P eckham . G ra d y c o n c lu d e d th a t th ese tests are n o t sufficiently biased to ju stify a d isc o n tin u a tio n o f th e ir use. E x am in atio n o f th e tran sc rip ts o f these cases reveals th a t each ju d g e was p resen ted w ith a great deal o f te ch n ic al in fo rm a tio n from ex p e rts testify in g for b o th sides co n c ern in g th e bias issue. U n ab le to reach a firm co n c lu sio n from th is m o u n ta in o f co nflicting d ata, th e ju d ic ia l decisions reveal th a t th e ju d g es essentially ignored m u ch o f the ex p e rt te stim o n y an d reach ed th e ir own co n c lu sio n s a b o u t test bias based on tw o d ifferent criterio n , b o th o f w hich are eq u ally w rong from a te ch n ic al sta n d p o in t. It is clear from Ju d g e P eck h am s d ecision a n d from his sta te m e n ts d u rin g th e trial th a t he accepted as an in c o n tro v e rtib le fact th a t th e re is n o dif­ ference in th e “tru e " level o f reta rd a tio n betw een vario u s racial a n d eth n ic groups. T herefore, an y te st th a t p u rp o rts to show such a difference m u st be biased. Such an arg u m e n t is circ u lar w ith o u t o th e r ev id en ce for th e asser­ tio n o f equal levels o f re ta rd a tio n , b u t it has th e very useful p ro p e rty o f en d in g discussion. H aving heard all th e ex p e rt te stim o n y a b o u t c u ltu ra l bias in intelligence tests d u rin g th e P A SE case. Ju d g e G ra d y decid ed th a t he c o u ld n 't decide. H e th erefo re e x a m in e d th e tests in q u estio n o n an ite m - b y -ite m basis, an d d e te rm in e d for h im s e lf how m a n y ite m s lo o k e d b iased . U n lik e Ju d g e P eck h a m , w ho fre q u e n tly cited e x p e rt te stim o n y to b ack up his c o n ­ clusions, Judge G ra d y was n o t co n v in ced th a t th e ex p erts testifying at th e trial w ere th em selves being very objective. U n fo rtu n a tely , G ra d y ’s m e th o d o f m easu rin g bias is useless w ith o u t d a ta o n how test ta k ers actu ally p er­ fo rm on each q u estio n . In th e absence o f w h at he felt to be reaso n ab le ex p e rt testim ony, a n d lacking ex p e rt know ledge him self. Ju d g e G ra d y w as forced in to m a k in g a decision, on faulty g rounds, th a t affected th e lives o f h u n d re d s o f schoolchildren. T h e controversy su rro u n d in g intelligence an d a p titu d e testin g has im ­ p o rta n t p ractical co n seq u en ces, b u t th e p olitical n a tu re o f th e con tro v ersy seem s to have o b scu red th a t it is highly tech n ical as well. W h en tech n ical issues becom e im p o rta n t m a tte rs o f p u b lic policy, w h eth e r in th e co u rts, th e legislatures, o r th e new s m edia, th e adversary n a tu re o f political d eb ate will in evitably obscu re an objective assessm ent o f ex p e rt o p in io n . A n ac cu ­ rate p ic tu re o f ex p e rt o p in io n a b o u t intelligence an d a p titu d e testin g is th erefo re needed. Such a survey is n o t a m e an s o f settlin g th e tech n ical issues— scientific q u estio n s c a n n o t be answ ered by c o n sen su s— b u t is an a tte m p t to re m a in unb iased in th e one elem e n t o f an essentially p o litical d ecision w here objectivity is m o st im p o rta n t. T h e next fo u r ch a p te rs o f th is book will discuss th e fo u r m a jo r areas o f c o n te n tio n in the IQ controversy: (1) th e n a tu re o f intelligence, or, m o re

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accurately, w h at intelligence tests m easure; (2) th e h eritab ility o f IQ ; (3) th e n a tu re o f racial a n d class differences in intelligen ce te st scores, in c lu d in g a d iscussion o f th e bias issue; a n d (4) th e use a n d m isuse o f intelligence an d a p titu d e tests. T hese ch a p te rs will in c lu d e a s u m m a ry o f th e p o sitio n s held on each o f th e issues by th e v arious c o n s titu e n ts in th e IQ d eb ate. T h e d iscussion will focus, however, on th e results o f a large scale survey o f ex p e rt o p in io n on contro v ersial aspects o f intelligence an d a p titu d e testing. M any o f th e issues dealt w ith in the follow ing ch ap ters, a n d in th e q u e s­ tio n n a ire , have n o t been th e su b ject o f m u c h p u b lic d iscu ssio n (i.e., new s m e d ia coverage), b u t have been im p o rta n t elem e n ts in th e lo n g er a n d m o re co m p re h en siv e d e b a te a b o u t te stin g in th e scholarly literatu re . It is h o p ed th a t readers, p articu la rly th o se charged w ith p u b lic policy decisions, will th ereb y gain a fuller u n d e rsta n d in g o f th e sources o f c o n te n tio n in th e IQ controversy an d , m o st im p o rta n t, w here th e ex p e rt p o p u la tio n sta n d s on th ese issues. C h a p te rs 4 an d 5 also in c lu d e an an aly sis o f th e rela tio n sh ip betw een th e d em o g ra p h ic a n d b ac k g ro u n d ch aracteristics o f o u r ex p e rt sam ple, a n d th e ir o p in io n s a b o u t testing. C h a p te rs 6 a n d 7 describe th e results o f a c o n te n t an aly sis o f new s m ed ia coverage o f th e m o d e rn IQ controversy. We have an a ly zed all coverage o f te stin g -re la te d issues ap p e arin g in ten m a jo r p rin t a n d telev isio n new s sources from th e years 1969 (the year o f J e n s e n ’s sem in al article) to 1983, inclusive. T h e analysis co n c e n tra te d o n how th e v ario u s co n tro v ersial is­ sues w ere p rese n ted a n d p a rtic u la rly o n how ex p e rt o p in io n a b o u t th ese issues was rep resen ted . C o m p ariso n betw een these results a n d th o se o f th e ex p e rt survey will provide a m e asu re o f new s m ed ia ac cu racy on coverage o f th e IQ controversy. A d d itio n a lly C h a p te r 7 in clu d es th e resu lts o f a survey o f jo u rn a lis t o p in io n a b o u t key testin g issues, as w ell as ratin g s o f new s m edia coverage from o u r testin g experts. T h e co n c lu d in g ch a p te r p resen ts a synthesis o f th e survey an d c o n te n t­ analysis results a n d a m o re general d iscussion o f th e rela tio n sh ip betw een science an d politics. We will also discuss th e role o f p u b lic o p in io n in th e IQ contro v ersy an d th e influ en ce o f th e m edia, ac ad e m ia , a n d th e g eneral p u b lic o n pu b lic policy. It is im p o rta n t to n o te, before begin n in g a d iscu ssio n o f th e im p o rta n t issues in th e controversy, w h at th is b o o k is not ab o u t. We will n o t ex a m in e th e contro v ersy su rro u n d in g a c h ie v em e n t tests— th o se tests in te n d e d to m easu re specific know ledge, ra th e r th a n skills o r abilities. T h ere will, th e re ­ fore, be no d iscussion o f tw o recen tly d isp u ted testin g issues; m in im u m c o m p ete n cy testin g for stu d e n ts, a n d te a c h e r c o m p ete n cy testing. T h ese tests a re aim ed a t m easu rin g th e know ledge req u ired fo r g ra d u a tio n a n d teach in g , respectively, n o t a p titu d e o r intelligence. T h ere will, however, be co n sid erab le discussion o f th e m u c h -d e b a te d a p titu d e -a c h ie v e m e n t d is­

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tin c tio n ; W h a t sep arates a c h ie v em e n t fro m a p titu d e a n d intelligence tests, o th e r th a n th e test m ak ers’ in te n tio n s? A dditionally, we will n o t be c o n c e rn e d w ith new er an d m o re rad ical c o n c ep tio n s o f intelligence an d testing such as H ow ard G a rd n e r's “ m u ltip le in telligences,” o r R o b e rt S tern b erg ’s T riarchic T heo ry .80 T h ese recen t d e­ v elo p m en ts are im p o rta n t c o n trib u tio n s to th e lite ra tu re on in telligence th a t m ay very well lead to fu n d a m e n ta l changes in th e way we th in k a b o u t an d m easure in tellectu al skills, b u t th ey have very little to d o w ith th e issues o f fu n d a m e n ta l co n c ern in the IQ co n tro v e rsy — th e validity o f tests, th e h eritab ility o f IQ , th e n a tu re o f g ro u p differences in te st scores, test use a n d m isu se— save th e q u estio n o f the n a tu re o f intelligence. Even here, th ese new ap p ro a ch es have yet to have m u c h im p a c t on th e lo n g -sta n d in g p u b lic discussion o f w h at “ intelligence” is. T h e sam e is tru e for m o st o f m o d e rn cognitive science. O u r p rim a ry c o n c e rn is w ith th e controversy over intelligence a n d a p titu d e testing, n o t w ith rec en t d ev e lo p m e n ts in th e stu d y o f m en tal processes. N otes 1. A rthur R. Jensen, Genetics and Education (New York: Harper & Row, 1972), p. 46. 2. Ibid., p. 24. 3. Although most of the more popular attacks on Jensen tended to be quite ad hominem, one of the few major exceptions has been Thomas Sowell, a con­ servative black economist. While Sowell has strongly criticized Jensen’s con­ clusions. he has always treated him seriously and with civility. Thomas Sowell, Race and Economics (New York: David McKay. 1975). 4. SPSSI, “ Statem ent on C urrent IQ Controversy: Heredity Versus Environ­ m ent,” American Psychologist 24 (1969): 1039-1040. 5. Jensen, p. 39. 6. “Born Dumb?” Newsweek 31 March 1969, p. 84. 7. Jensen, p. 14; telephone interview with Lee Edson, author of “jensenism” arti­ cle, 19 October 1985. 8. Leon J. Kamin. The Science and Politics o f IQ (Potomac, MD: Lawrence Erlbaum. 1974); Andrew J. Strenio. The Testing Trap (New York: Rawson, Wade, 1981); Paul L. Houts, ed., The M yth o f M easurability (New York: Hart Publishing, 1977); Stephen Jay Gould, The M ismeasure o f Man (New York: Norton, 1981). 9. "New National Organization to Fight for Fair Standardized Tests.” FairTest press release, 24 October 1985. 10. Carl Dimengo, “ Basic Testing Programs Used in M ajor School Systems Throughout the United States in the School Year 1977-78," Akron Public Schools. March 1978. 11. Hobson v. Hansen, 269 FSupp. 401 (D. D.C. 1967). 12. Larry P. v. Riles. 495 F.Supp. 926 (N.D. Cal. 1979). 13. Larry P v. Riles, 793 F.2d 969 (9th Cir. 1984).

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14. Telephone interview with D onna Bolen, Special-Education Consultant, Cal­ ifornia State D epartment o f Education, 10 July 1984. 15. “IQ Tests Restricted by Race,” Washington Post, 6 July 1987, p. A3; “Civil Rights Panel to Study California Ban on IQ Tests for Blacks,” Associated Press 13 July 1987. 16. Griggs v. Duke Power Co., 401 U.S. 424 ( 1971 ). 17. A rthur R. Block and Michael A. Rebell, Competence Assessment and the Cou­ rts: An Overview o f the State o f the Law (ERIC ED 192 169), p. 16. 18. There may be some relief in sight for supporters of employment testing, as the EEOC, in response to increasing complaints about its unrealistic standards, announced in May 1985 that it is reviewing its Guidelines and may relax them. It would not pay to be optimistic, however, as the EEOC was close to relaxing it standards in 1976, only to be persuaded at the last minute by the NAACP to republish the original Guidelines. M. A. Pearn, Employment Testing and the Goal o f Equal Opportunity: The American Experience (London: Runnymede Trust. July 1978), p. 28 (ERIC UD 019 829). 19. Mary L. Tenopyr, “The Realities of Employment Testing,” American Psychol­ ogist 36 (1981): 1121. 20. M. C. Miner and M. G. Miner, Employee Selection Within the Law (Wash­ ington, DC: The Bureau of National Affairs, 1978). 21. R. M. Guion, quoted in Pearn, p. 29. 22. Douglas v. Hampton, 338 ESupp. 18 (D. D.C. 1972). 23. National Education Association, Measurement and Testing: An NEA Perspec­ tive (Washington, DC: Author, 1980). 24. R. T. H artnett and R. A. Feldmesser, “College Admissions Testing and the Myth of Selectivity: An Unresolved Question and Needed Research ” A A H E Bulletin 32 ( 1980):3—6. 25. J. McKeen Cattell, “ Mental Tests and Measurement,” M ind 15(1890), p. 373 ff. 26. Clark Wissler, “The Correlation of Mental and Physical Tests,” Psychological Review, Monograph Supplement 3 ( 1901 ). 27. A rthur R. Jensen, “Reaction Time and Psychometric g,” in A Model fo r Intel­ ligence, ed. Hans J. Eysenck (Berlin: Springer-Verlag, 1982), pp. 93-132; Lang­ don E. Longstreth, “Jensen’s Reaction-Tim e Investigations of Intelligence: A Critique,” Intelligence 8 ( 1984): 139-160: A rthur R. Jensen and Philip A. Ver­ non. “Jensen’s Reaction-Tim e Studies: A Reply to Longstreth,” Intelligence 10 (1986): 153-179; Langdon E. Longstreth, “The Real and the Unreal: A Reply to Jensen and Vernon,” Intelligence 10 ( 1986): 181-191; A. T. Welford, “ Long­ streth versus Jensen and Vernon on Reaction Time and IQ: an Outsider's View,” Intelligence 10 (1986): 193-195. 28. Stella E. Sharp, “Individual Psychology: A Study in Psychological M ethod,” American Journal o f Psychology 10(1898-1899):329-391. 29. Alfred Binet, “Attention et Adaptation,” L'Année Psychologique 6 ( 1900) 248­ 404. 30. Alfred Binet and Theodore Simon, “Méthodes Nouvelles pour le Diagnostic du Niveau Intellectuel des A norm aux,” L ’A nnée Psychologique 11 ( 1905): 191­ 244. 31. William Stem, Die Différentielle Psychologie (1911). 32. Lewis M. Term an, The M easurem ent o f Intelligence (Boston: Houghton Mifflin. 1916). 33. Alfred Binet and Theodore Simon. “Sur la Nécessite d’une Méthode Applica-

Introduction: The IQ Controversy in Perspective

39

ble au Diagnostic des Arriérées Militaires,” Annales Médico-Psychologiques, (January/February 1910). 34. Daniel Resnick, “ History of Educational Testing,” in Ability Testing: Uses, Consequences, and Controversies, Part II, eds. Alexandra K. W igdorand Wen­ dell R. G arner (Washington, DC: National Academy Press, 1982), p. 182. 35. Matthew Hale, "History of Employment Testing,” in Ability Testing: Uses, Consequences, and Controversies. Part II, eds. Alexandra K. Wigdor and Wen­ dell R. G arner (Washington, DC: National Academy Press, 1982), p. 13. 36. Alexandra K. Wigdor and Wendell R. Garner, eds.. Ability Testing: Uses, Con­ sequences, and Controversies, Part I (Washington, DC: N ational Academy Press, 1982), p. 89. 37. Loren Baritz, The Servants o f Power (Middletown, CT: Wesleyan University Press, 1960), p. 67. 38. Daniel J. Kevles. In the Nam e o f Eugenics: Genetics and the Uses o f H uman Heredity (New York: Knopf, 1985). 39. Kamin, Science and Politics o f IQ. 40. H. H. Goddard. “ Mental Tests and the Immigrant,” The Journal o f Delin­ quency 2 {\9\1):24?>-211. 41. Mark Snyderman and R. J. Herrnstein. “Intelligence Tests and the Immigra­ tion Act of 1924.” American Psychologist 38 ( 1983):986—995. 42. Edwin G. Boring, "Facts and Fancies of Immigration,” New Republic, 25 April 1923, pp. 245-246; Percy E. Davidson, "The Social Significance of the Army Intelligence Findings,” Scientific M onthly 16 ( 1923): 184—193; M. B. Hexter and A. Myerson, “ 13.77 Versus 12.05: A Study in Probable Error,” Mental Hygiene 8 ( 1924):69—82; Kimball Young, Review of A Study o f American Intel­ ligence, Science 57 ( 1923):666—670. See also Gould. 43. Robert Yerkes, Foreword to Carl C. Brigham, A Study o f American Intelligence (Princeton. NJ: Princeton University Press, 1923). 44. Lewis M. Terman, “Were We Born That Way?” World’s Work 44 ( 1922):655— 660. 45. Terman, Measurement o f Intelligence, p. 72. 46. Ibid.. p. 92. 47. Lippm ann-Term an debate reprinted in N. J. Block and Gerald Dworkin, eds.. The IQ Controversy (New York: Pantheon Books, 1976), pp. 4-44. 48. Ibid.. p. 37. 49. Lewis M. Terman and Maude A. Merrill, Measuring Intelligence (Boston: Houghton Mifflin, 1937). 50. David Wechsler. The Measurement o f Adult Intelligence (Baltimore: Williams & Williams, 1939). 51. Philip H. Dubois, A H istory o f Psychological Testing (Boston: Allyn and Bacon, 1970), pp. 112-120. 52. Carl C. Brigham, "Intelligence Tests of Immigrant Groups,” Psychological R e­ view 37 (1930): 158-165. 53. Hale, pp. 23-24. 54. Benjamin Fine, “More and More, the IQ Idea Is Questioned,” New York Times Magazine, 18 September 1949, pp. 7 , 12-1 A. 55. Cited in Hale. p. 26. 56. Baritz, pp. 77-95, 139-166. 57. Theoretically, Americans had always believed that rewards should be dis­ tributed on the basis of effort and capacity, but the Protestant establishment

40

The IQ Controversy

that controlled the major institutions of society had assumed that character and style were im portant in determining these essentials. In the afterm ath of the war, this view changed rapidly, and tests of intelligence and aptitude were seen as mechanisms for insuring that the biases inherent in evaluating “character” no longer interfered with employment decisions or admission to prestigious colleges and universities. The change reflected a sharp decline in anti-Sem i­ tism, for, at that point, high achieving Jews had borne the brunt of such dis­ crim ination. Indeed, Jewish intellectuals and professionals were in the forefront of those pressing for decisions being made solely on the basis of objective measures of capacity and for the elimination of quota-like arrange­ ments that had barred many of them from certain institutions of higher educa­ tion. Indeed the shift to “objective” measures of aptitude was partly responsible for the rapidity with which Jews (and Japanese Americans) advanced in the post war period. Stanley Rothm an and S. Robert Lichter, Roots o f Radicalism: Jews, Christians, and the New Left (New York: Oxford University Press, 1982). 58. Herbert H. Hyman and Paul B. Sheatsley, “Attitudes toward Desegregation,” Scientific American (December 1956):35—39. 59. Fine, p. 72. 60. Ibid., p. 74. 61. Frank C. J. McGurk,“ ‘Psychological Tests-A Scientist’s Report on Race Dif­ ferences,” U.S. News and World Report 21 September 1956:92-96. 62. Otto Klineberg et al„ “ 18 Social Scientists Discuss: Does Race Really Make a Difference in Intelligence?” U.S. News and World Report 26 October 1956 74­ 76. 63. Henry E. G arrett. "The SPSSI and Racial Differences,” American Psychologist 17 (1962):260—263. 64. R. Travis Osborne and Frank C. J. McGurk, The Testing o f Negro Intelligence, Volume 2 (Athens, GA: The Foundation for Human Understanding, 1982), p. xiii. 65. Dwight J. Ingle, “Racial Differences and the Future,” Science 146 (1964):375379; comments in Science 146 (1964): 1415-1418, 1526-1530, and Science 147 (1965):6-7. 66. Edward Zigler and Karen Anderson, “An Idea Whose Time Has Come: The Intellectual and Political Climate for Head S tart,” in Edward Zigler and Jeanette Valentine, eds.. Project Head Start (New York: Free Press, 1979). 67. Daniel Bell, The Cultural Contradictions o f Capitalism (New York: Basic Books, 1972); Lawrence M. Friedman, Total Justice (New York: Russell Sage Foundation, 1985). 68. A rthur R. Jensen, “How Much Can We Boost IQ and Scholastic Achieve­ ment?" Harvard Educational Review 39 (1969):2. 69. Lee J. Cronbach, “Heredity, Environment, and Educational Policy,” Harvard Educational Review 39 (1969):90. 70. Westinghouse Learning Corp., The Impact o f H ead Start: An Evaluation o f the Effects o f H ead Start on Children’s Cognitive and Affective Development. E x­ ecutive Sum m ary (Washington, DC: Clearinghouse for Federal Scientific and Technical Information, June 1969) (ED 036 321). 71. American Anthropological Association, “Motions,” Newsletter 13 (1972): 12. 72. “The IQ Myth,” 60 M inutes segment. CBS, 26 June 1977. 73. Oliver Gillie, “Crucial Data Was Faked by Eminent Psychologist,” Sunday Times (London), 24 October 1976; Nicholas Wade, “I.Q. and Heredity: Suspi­ cion of Fraud Beclouds Classic Experiment,” Science 194 (1976):916-919.

Introduction: The IQ Controversy in Perspective

41

74. See, for example, “Correspondence” in the Bulletin o f the British Psychological Society throughout 1977. 75. L. S. Hearnshaw, Cyril Burt: Psychologist (New York: Vintage Books, 1979). 76. This clash, at least as it affects opinion and policy toward testing, is not unique to capitalist society. The Chinese, who have used standardized tests in employ­ ment and education for over 3, 000 years, have twice during the past 40 years eliminated and then reinstated examinations for admission to schools of higher education. Each time the exams were eliminated as a result of complaints that certain economic and cultural groups were being disproportionately denied admission to these schools as a result of the tests, and each time the tests were reinstated in response to declining academic standards in the universities. The same pattern is to be found in the Soviet Union, and various Eastern European countries. After a period during which equal potentials were emphasized, schol­ ars in these countries now maintain that differences in IQ are at least partly determ ined by the genes. Ana Teresa G utierrez and Robert E. Klitgaard, H igher E ducation and A d m issio n s in the P eople’s R epublic o f C hina (Cambridge. MA: President and Fellows of Elarvard College, 1982); H. J. Ey­ senck. “After Binet, Back to G alton,” Encounter, (February 1983):74—79. 77. “Whatever Became o f ‘Geniuses’?” Time 19 (December 1977):89. 78. R. J. H errnstein, “ IQ Testing and the Media,” Atlantic M onthly, (August 1982):68—74. 79. PASE v. Hannon, 506 ESupp. 831 (N.D. 111. 1980). 80. Howard Gardner, Frames o f Mind: The Theory o f Multiple Intelligences (New York: Basic Books, 1983); Robert J. Sternberg. Beyond IQ: A Triarchic Theory o f H uman Intelligence (New York: Cambridge University Press, 1985).

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2 The Nature of Intelligence I ain’t no psychiatrist, I ain i no doctor with degrees, but it don't take too much high IQ to see what you 're doin' to me. — " T h i n k ” by A re th a F ra n k lin a n d Ted W h ite , F o u r te e n th H o u r M usic, B M I, 1968

In M arch 1921, at a tim e w hen th e practical a p p lica tio n o f m e n tal testin g w as b egin n in g a d ra m a tic rise, an d before th e pu b lic co n tro v ersy over th e A rm y testin g results h ad h eated up, th e Jo u rn a l o f E d u ca tio n a l P sychology p u b lish ed a sy m p o siu m o n “ Intelligence a n d Its M e a su re m e n t,” in w hich fo u rte en o f th e m o st im p o rta n t m en tal testers briefly expressed th e ir views on th e to p ic a t h a n d .1 A su b stan tia l m ajo rity o f these ex p e rts ap p eared to be in ag re em e n t w ith w hat o n e tester called th e “ c o m m o n ly accep ted defi­ n itio n o f in tellig en ce” as m e n tal a d a p ta tio n to ch an g in g en v iro n m e n ta l stim u li (so m etim es called th e capacity to learn). M an y also em p h asized th a t intelligence is n o t a u n ita ry tra it, a n d th a t o n e m u st m easu re general in tellectu al capacity by sa m p lin g a w ide variety o f its in te rre la te d su b c o m ­ p o n e n ts. T h e m a jo r so u rce o f d isa g re e m e n t b etw een re s p o n d e n ts c o n ­ c e rn ed th e b rea d th o f ad a p tiv e experience to be co n sid ered “ intelligent.” For exam ple, Lew is T erm an felt th a t “ [a]n in d iv id u al is in tellig en t in p ro ­ p o rtio n as he is able to c a rry o n ab stra ct th in k in g ,”2 a n d w en t so far as to castigate those w hose “ sense o f psychological values” was so d istu rb e d as to believe th a t “ th e in d iv id u al w ho flounders in ab stra ctio n s b u t is able to h an d le tools skillfully, o r play a good gam e o f baseball, is n o t to be co n sid ­ ered necessarily less in tellig en t th a n th e in d iv id u al w ho ca n solve m a th e ­ m atical eq u a tio n s, acq u ire a huge vocabulary, o r w rite poetry.” A t th e o th e r ex trem e. Brow n U niversity psychologist S. S. C olvin asserted th a t “ in te l­ ligence tests sho u ld explore as m a n y aspects o f h u m a n ab ility as possible.” 3 M o st resp o n d e n ts agreed w ith T erm an to th e ex ten t th a t th e y in c lu d ed

43

44

The IQ Controversy

som e fo rm o f higher m e n tal fu n ctio n , like ab stra ct reasoning, p ro b lem solving, o r d ecision m aking, in th e ir d efin itio n o f intelligence. Besides th e n a tu re o f intelligence, tw o fu rth e r to p ic s w ere fre q u en tly discussed by sy m p o siu m p a rtic ip a n ts. R egardin g th e ab ility o f in telligence tests to m easu re intelligence, tho se ex p e rts h o ld in g b ro a d e r d efin itio n s w ere n atu ra lly inclin ed to believe th a t tests w ere so m ew h at lim ite d in c o n te n t. T h u s, for exam ple, T e rm a n ’s suggestions fo r im p ro v in g tests p ri­ m arily involved refin em en ts o f existing m odels, w hile C o lv in asserted th a t tr u e p ra c tic a lity w o u ld re q u ire te sts o f m u c h b r o a d e r sco p e. O n th e h eritab ility issue, am o n g th o se expressing an o p in io n , th e re w as u n a n ­ im o u s ag re em e n t th a t tests m e asu red differences in b o th in n a te cap acity a n d ac q u ired know ledge, a n d th a t intelligence tests b ecam e b e tte r m e a ­ sures o f cap acity as in d iv id u al differences in th e o p p o rtu n ity to ac q u ire know ledge w ere equalized. Id en tical o p in io n s o n th e h e re d ity -e n v iro n m e n t issue w ere expressed by tw elve m e n tal testers polled by F ra n k F re em a n in 1923.4 T h is survey, p u b ­ lished in th e C e n tu ry M a g a zin e, covered a w id er ran g e o f to p ic s th a n th e 1921 sy m p o siu m . In a d d itio n to a sta te m e n t a b o u t in n a te cap acity an d ac q u ired know ledge, F re em a n w as able to get u n a n im o u s o r n ea r u n a n ­ im o u s ag reem en t to sta te m e n ts in d ic atin g th e u sefulness o f intelligence tests, th e ir validity as m easu res o f g eneral m e n ta l ability, a n d th a t g ro u p differences in intelligence are th e result o f differences in b o th e n v iro n m e n t an d in h e ritan c e. L ike th e 1921 sy m p o siu m , th e co n sen su s b ro k e dow n w hen F re em a n assessed a g re em e n t w ith th e sta te m e n t th a t g eneral m e n tal ability “ rep rese n ts ease o f le arn in g in th e in tellectu al field.” E x p erts co u ld n o t agree as to w h at “th e in tellectu al field” com p rised . S om e b alk ed a t th e suggestion o f even a tte m p tin g to d ev e lo p a p recise d e fin itio n o f in te l­ ligence, claim in g e ith e r th a t th e re w ere insufficient d a ta o r th a t th e q u es­ tio n was in c o n seq u e n tia l c o m p ared to th e issues o f w h at th e tests w ere m easuring, a n d th e possible uses to w hich th ey co u ld be p u t. T h e C e n tu ry M a g a zin e poll w as p u b lish ed co in cid e n t w ith th e first IQ controversy. T h e results o f th e poll w ere in strik in g c o n tra st to th e views expressed by th e p o p u la r critics o f th e day, w h o claim ed th a t in telligence tests h ad little to d o w ith intelligence, a n d th a t differences in te st scores w ere m ostly th e resu lt o f differences in train in g . C ritics also p o rtra y ed m e n ta l te ste rs, in c o rre c tly a c c o rd in g to th e C e n tu ry poll, as b eliev in g th em selves to be in possession o f p u re m easu res o f in n a te ab ility (see th e discussion o f W alter L ip p m a n n ’s c o m m e n ts in C h a p te r 1). O n e are a w here th e critics seem ed to be right a b o u t th e testers was th e ir in a b ility to agree o n a d efin itio n o f intelligence, a t least in its p articu la rs. T h e d isa g re em en t am o n g testin g ex p e rts a b o u t a d efin itio n o f in te l­ ligence a p p a re n t in th e 1921 a n d 1923 polls m ay very well be an accu rate

The Nature of Intelligence

45

re p re se n ta tio n o f ex p e rt o p in io n at th e tim e. It m ig h t also reflect th e lack o f a n y a tte m p t to co n so lid a te responses a n d look fo r u n d erly in g unity. Iro n ­ ically, th e te c h n iq u e best suited to discover such h id d en stru ctu re , facto r analysis, was developed as a resu lt o f th e m e n ta l testin g m o v em en t. Yet, it w as sixty years before an y o n e a tte m p te d to ap p ly facto r analysis to o p in ­ io n s a b o u t th e n a tu re o f intelligence. In 1981, R o b e rt S tern b erg a n d his colleagues p u b lish ed th e results o f a survey in w hich a g ro u p o f laypersons a n d a g ro u p o f p sychologists c o n d u c tin g rese arch o n in te llig en ce w ere asked how ch a racteristic each o f 250 behaviors is o f an ideally in tellig en t p e rso n .5 T h e ratings o f th e tw o g roups w ere rem a rk a b ly sim ilar. M o re im pressive, th e ratings w ith in each g ro u p co u ld be largely ex p lain ed by th ree u n d erly in g factors (c o m p o n e n ts o f intelligence). A m o n g laypersons th ese factors w ere labeled “ p ractical p ro b le m -so lv in g ability,” “ verbal ab il­ ity,” a n d “social co m p eten ce.” A m ong ex p erts they w ere “ verbal in te l­ lig e n c e ,” “ p r o b le m - s o l v in g a b i lity ,” a n d “ p r a c tic a l in te llig e n c e .” (S tern b erg drew m u c h o f th e im p e tu s for his ow n T riarch ic T heory, in w hich p ractical intelligence plays a p ro m in e n t role, from th e results o f th is survey.) T h e la tte r resu lt lends credence to th e c o n te n tio n o f th e APA ad h oc C o m m itte e on E d u ca tio n a l U ses o f Tests w ith D isad v an tag ed S tu ­ d en ts, in response to critics o f testing, th a t “th e re is a co n sen su s am o n g psychologists as to th e k in d s o f b ehaviors th a t are labeled in tellectu al.”6 In 1986, S tern b erg an d D ouglas D e tte rm a n p u b lish ed a b o o k en title d W h a t Is Intelligence?, an u p d ate o f th e 1921 Jo u rn a l o f E d u ca tio n a l P sy­ chology sy m p o siu m , in w hich tw en ty -fiv e c o n te m p o ra ry ex p e rts o n in te l­ ligence resp o n d to th e title q u e s tio n .7 T h e results o f th e tw o sym posia c o n ta in som e strik in g sim ilarities. In each case, th e re is a co n sen su s o f o p in io n a b o u t th e n a tu re o f intelligence, in th a t th e m o st fre q u en tly m e n ­ tio n e d elem e n ts o f intelligence are h ig h er-lev el cognitive fu n ctio n s, su ch as ab stra ct reaso n in g a n d p ro b lem solving. T hese attrib u te s are m e n tio n e d by a t least h a lf the c o n trib u to rs in each sy m p o siu m . A lso p ro m in e n t in b o th sym posia, however, is d isag reem en t over th e b re a d th o f th e d efin itio n o f intelligence, as is d eb ate over w h eth e r intelligence is a general ability o r a co n c a te n a tio n o f m a n y sep arate ab ilities.8 U n fo rtu n a tely , th e re is little else we can say a b o u t co n sen su s, o r an y o th e r level o f ag re em e n t o r d isag reem en t am o n g ex p erts o n issues related to intelligence a n d a p titu d e testing. We have, at presen t, no concise d escrip ­ tio n o f th e n a tu re an d variety o f ex p e rt o p in io n o n such issues as th e origin an d stability o f intelligence, test use a n d m isuse, bias in testing, an d racial a n d ec o n o m ic gro u p differences in IQ. T h e n ext fo u r ch a p te rs o f th is b o o k will describe th e results o f such a survey. We w ish to em p h asize again th a t th is survey is n o t m e a n t to settle th e IQ controversy, b u t is m erely an

46

The IQ Controversy

a tte m p t to allow th e ex p e rt voice to be h ea rd in as objective a fo ru m as possible. Survey M ethodology T h e p u rp o se o f th is research w as to survey e x p e rt o p in io n a b o u t th e IQ controversy. B ecause th e contro v ersy is a b ro ad on e, th e p o p u la tio n th a t co n stitu te s “ex p e rts” is n o t im m ed ia te ly a p p a re n t. It w as th e re fo re neces­ sa ry to d e fin e th e p o p u la tio n th ro u g h th e v a rio u s c o n s id e ra tio n s th a t g uided sam p le selection. T h ere w ere th ree p rim a ry co n sid eratio n s. F irst, th e p o p u la tio n w as to be n e ith e r so b ro ad th a t it c o n ta in e d a large p ro p o r­ tio n o f in d iv id u als w ith little o r n o ex p erien ce w ith intelligence o r testing, n o r so n arro w as to in c lu d e on ly tho se w ho m ig h t be co n sid ered to have a vested in te rest in testing. A n ex am p le o f th e fo rm e r w ould be all p sy ch o lo ­ gists a n d ed u c ato rs, w hile th e la tte r p o p u la tio n m ig h t co n sist o nly o f m e m ­ bers o f th e N atio n al C o u n c il on M e a su re m e n t in E d u c a tio n (N C M E ). N C M E m e m b ers u n d o u b te d ly are ex p e rts o n testing, b u t th ere are m a n y social scientists a n d ed u c ato rs w ho can reasonably^ be assu m ed to have know ledge o f th e ac ad e m ic lite ra tu re o n at least so m e aspects o f th e IQ controversy, b u t w ho d o n o t deal w ith tests as an essential p a rt o f th e ir w ork. We w ished to in c lu d e these in d iv id u als as well.: T h e second co n sid eratio n in defining a p o p u la tio n o f ex p erts w as to in c lu d e in d iv id u als w ith a w ide v ariety o f perspectives o n th e p ro b lem , even tho se w ho m ight have expertise on on ly a sm all p a rt o f th e c o n tro ­ versy. F or th is purp o se, th e p o p u la tio n w as div id ed in to p rim a ry a n d sec­ o n d a ry g ro u p s. P rim a ry g ro u p s w ere th o se p ro fe ssio n a l o rg a n iz a tio n s w hose m e m b ers m ig h t be expected to be know ledgeable o n several I Q related topics. S eco n d ary g ro u p s w ere o rg an iz atio n s w hose m em b ers w ere likely to know testin g fro m only a n arro w perspective. P rim a ry g ro u p s in c lu d e d th e A m e ric a n E d u c a tio n a l R e se a rc h A sso c ia tio n (A E R A ), N C M E , a n d th e D ev e lo p m e n tal Psychology, E d u ca tio n a l Psychology, E val­ u a tio n a n d M e asu rem en t, a n d S chool P sychology d iv isio n s o f th e A m er­ ic a n P sy ch o lo g ica l A sso c ia tio n (APA). S e c o n d a ry g ro u p s c o n s is te d o f m e m b ers o f th e A m eric an Sociological A sso ciatio n (ASA) id en tified as sociologists o f e d u c atio n (in clu d ed for ex p ertise in th e role o f te stin g in society), th e B ehavior G en e tic s A ssociation (for ex p ertise in heritability), th e C ognitive Science Society (for expertise o n th e n a tu re o f intelligence an d cognitive abilities), a n d tw o o th e r divisio n s o f th e APA, C o u n selin g Psychology (for expertise in th e use o f tests in counseling), an d In d u strial a n d O rg a n iz atio n a l Psychology (for expertise in e m p lo y m e n t testing). T h e final criterio n was th a t th e sam p le be w eighted in favor o f th o se w ith th e m o st expertise, as in d ic ated by research an d p u b lic atio n s o n issues

The Nature of Intelligence

47

related to intelligence an d testing. T herefore, on ly sch o larly o rg an izatio n s w ere sam pled. T h e sam ple w as also w eighted tow ard th o se o rg an izatio n s, a n d m em b ers o f th e org an izatio n s, th o u g h t to have th e m o st expertise. B ecause m e m b ers o f p rim a ry g roups w ere believed to have m o re overall e x p ertise th a n m em b ers o f se co n d a ry groups, tw ice as m a n y m e m b ers w ere selected from each p rim a ry g ro u p as from each se co n d a ry group. For th o se o rg an iz atio n s w here it was possible to se p arate Ph. D. fro m n o n - P h . D. m em b ers, only m e m b ers w ith d o cto ra tes w ere sam pled . W ith in each d iv i­ sion o f th e APA th e re are tw o classes o f Ph. D. m em b ers. M em b ers an d Fellows. M em bers need only have a psychology Ph. D. Fellows m u st first have been M em bers, m u st have a t least five years o f ex p erien ce in p sy ch o l­ ogy b ey o n d th e Ph. D. , a n d m u st be n o m in a te d an d elected by o th e r APA m em b ers based on “ evidence o f u n u su a l an d o u tsta n d in g c o n trib u tio n or p e rfo rm a n c e in th e field o f psychology.” D espite th e fact th a t th e re are far few er Fellows th a n M em bers w ithin each division, h a lf o f th e sam p le from each division w as draw n from th e Fellows a n d h a lf from th e M em bers. T h e sam ple was draw n random ly, in the n u m b e rs in d ic ated in Table 2.1. from th e m o st recen t available m e m b ersh ip d ire c to ry o f each o f th e o rg an ­ izatio ns. T h e final sam p le co n sisted o f 1,020 social scien tists a n d ed u cato rs. T h e q u e stio n n a ire itself w as d ivided in to six sections. F o u r o f these TABLE 2.1 Composition of Survey Sample Primary Groups American Educational Research Association National Council on Measurement in Education American Psychological Association: Developmental Psychology Educational Psychology Evaluation and Measurement School Psychology Secondary Groups American Sociological Association: Education Behavior Genetics Association Cognitive Science Society American Psychological Association: Counseling Psychology Industrial and Organizational Psychology Total

N 120 120 60 60 60 60 60 60 60 60

Fellows Members Fellows Members Fellows Members Fellows Members

60 60 60 30 30 30 30

Fellows Members Fellows Members

1,020

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The IQ Controversy

co n ta in e d su b stan tiv e q u estio n s a b o u t intelligence a n d testing, a n d tw o asked a b o u t vario u s d e m o g ra p h ic a n d b ac k g ro u n d ch a racteristics o f th e resp o n d e n ts. T h e scope o f th e su b stan tiv e q u estio n s w as in te n d e d to in ­ clu d e m o st areas o f c o n te n tio n w ith in th e relev an t ac ad e m ic literatu re , w ith an em p h asis on areas o f p a rtic u la r c o n c e rn in th e p u b lic d ebate. T h e first su b stan tiv e section, labeled “ T h e N a tu re o f In tellig en ce,” will be th e focus o f d iscussion in th is chapter. T h e rem a in in g th ree su b stan tiv e sectio n s d ea lt w ith “ T h e H erita b ility o f IQ ,” “ R ace, Class, an d C u ltu ra l D ifferences in IQ ,” a n d “ T h e U se o f Intelligence T esting,” a n d will be co n sid ered in th e follow ing chapters. T h e first o f th e tw o d e m o g ra p h ic sections o f th e q u e stio n n a ire , “ P rofes­ sio n a l A ctiv itie s a n d In v o lv e m e n t w ith In tellig en c e T estin g ,” w as c o n ­ c e rn e d p rim a rily w ith m e a su rin g e x p e rtise a n d p u b lic ex p o su re . T h is section also co n ta in e d tw o m u lti- p a r t q u estio n s o f a m o re su b stan tiv e n atu re . T h e first asked resp o n d e n ts to rate each o f te n d ifferen t new s sources for accu racy in re p o rtin g issues related to in tellig en ce a n d testing. T h e second asked for ratin g s o f fo u rte en different a u th o rs as to th e q u ality o f th e ir w ork o n intelligence a n d testing. T h e final se ctio n o f th e q u e s tio n n a ire , “ P erso n al a n d S ocial B ack ­ g ro u n d ,” asked a b o u t th e re sp o n d e n t’s sex, age, m a rital statu s, e th n ic an d religious b ac k g ro u n d , an d c h ild h o o d fam ily in co m e. A g reem en t o r d is­ a g re em e n t w ith a series o f political sta te m en ts, an d a global p o litical m e a ­ su re (lib e ra l-c o n s e rv a tiv e ) w ere u se d to assess re s p o n d e n ts ’ p o litic a l perspectives. Follow ing p re -te s tin g w ith v arious g ro u p s o f testin g ex p erts, 1,020 q u es­ tio n n a ire s w ere m ailed in S ep te m b er o f 1984. A cover le tte r ex p lain ed th e p u rp o se o f th e q u e stio n n a ire (to help clarify co n fu sio n over testing), its im p o rta n c e in light o f the w idespread use an d co n tro v ersy over tests, a n d p ro m ise d co m p lete co n fid e n tia lity (the q u e s tio n n a ire itself co n ta in e d an ID n u m b e r for th e p u rp o se o f fo llo w -u p m ailings). B ecause m a n y resp o n d ­ e n ts w ere n o t expected to have ex p ertise in all areas o f testing, th e cover le tte r asked subjects to check th e N Q (N o t Q ualified) resp o n se fo r an y q u e stio n th ey d id n o t feel q ualified to answ er. T h is categ o ry also served for N o R e sp o n se /D o n ’t Know. A p p ro x im ately tw o w eeks after th e in itial m ailin g , p o stc ard re m in d e rs w ere sent to all subjects w ho h ad n o t yet resp o n d ed . A b o u t fo u r w eeks later, a second set o f q u e stio n n a ire s w as sen t o u t to th e re m a in in g n o n re sp o n ­ den ts. T h e final response tally c o n ta in e d 661 co m p leted q u e stio n n a ire s (65 percent). T h e re was little v aria tio n in response rate betw een th e v ario u s p rim a ry a n d se co n d a ry g roups w ith in th e sam ple. F o rty -n in e su b jects re­ tu rn e d th e ir q u e stio n n a ire s in d ic atin g th e y w ere n o t q u alified to an sw er an y o f th e su b stan tiv e q u estio n s. S eventeen sub jects w ere deceased o r o th ­

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erw ise in c a p a c ita te d , a n d tw e n ty -se v e n su b je cts sim p ly r e tu rn e d th e ir q u e s tio n n a ire s u n an sw ered w ith n o ex p lan a tio n . Two h u n d re d six ty -six , o r 26 p erc en t o f th e q u e stio n n a ire s were n o t re tu rn e d at all. P h o n e calls w ere m ad e to forty (15 p ercen t) o f th ese n o n res­ p o n d e n ts in o rd er to d e te rm in e if they differed in an y im p o rta n t way from re sp o n d e n ts a n d to as ce rta in th e ir reasons for n o n resp o n se. T h ese subjects w ere asked som e o f th e m o re im p o rta n t su b stan tiv e a n d d em o g ra p h ic q u estio n s, w ith m ixed success; these w ere in d iv id u als w ho h ad alread y n o t resp o n d e d to th ree m ailings. T h e ir responses to q u estio n s for w hich th ere w ere a sufficient n u m b e r o f answ ers for m e an in g fu l co m p ariso n w ere n o t significantly different from th o se o f re sp o n d e n ts to th e m ailed q u e s tio n ­ n aire. M ore in fo rm a tiv e p erh ap s w ere th e reasons th ese su b jects gave for n o t responding. All forty subjects answ ered th is q u estio n . T w en ty -th ree said th a t they w ere to o busy to resp o n d , a n d tw elve d id n o t feel qualified. O n ly six expressed an y aversion to th e q u e stio n n a ire itself (resp o n d en ts co u ld give m o re th a n o n e reason). In all. given th e n a tu re o f responses received fro m th e p h o n e sam ple, a n d th e ir reaso n s for n o t resp o n d in g to th e m ailed q u e stio n n a ire , th e re seem s little reason to believe th a t th e re­ sults w ould look significantly d ifferent h ad th e en tire sam p le o f 1,020 p a r­ ticip ated . P rofessional A ctivities and Involvement with Intelligence Testing T h e professional b ac k g ro u n d ch a racteristics o f survey re sp o n d e n ts are su m m arize d in T able 2.2. T h e degree o f expertise a b o u t in telligence a n d testin g varies w idely a m o n g resp o n d e n ts, b u t, o n th e w hole, th e sam p le is ad eq u ately ch a racterize d as ex p ert. A p p ro x im ately h a lf o f all re sp o n d e n ts are faculty m em b ers at a college o r university, a n d th e b u lk o f th e re­ m a in d e r classify th e m se lv es as p sychologists o r e d u c a tio n a l sp ecialists TABLE 2.2 Expertise of Sample Characteristic College or university faculty Other psychologist or educational specialist Current research on intelligence or testing Articles or chapters on intelligence or testing3 Speeches or lectures on intelligence or testing3 Served as news media source on intelligence or testing3 Administered individual intelligence test3 Administered group intelligence test3 ¡■Within th e p re v io u s tw o years.

% of Respondents 53.3 36.1 55 67 57 33 38.5 29.3

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w orking in so m e o th e r cap acity (e.g., in e le m e n ta ry a n d se co n d a ry e d u c a ­ tio n , for g o v ern m e n t, for th e testin g industry). F ifty -fiv e p erc en t a re p la n ­ n in g o r c a rry in g o u t rese arch in so m e a re a re la te d to in te llig en c e o r intelligence testing. T h e m o st c o m m o n areas o f research are th e n a tu re o f intelligence, test d e v e lo p m e n t an d v alid atio n , a n d testin g in e le m e n ta ry a n d se co n d a ry schools. S ix ty -sev en p erc en t o f re sp o n d e n ts have w ritten a t least o n e artic le or ch a p te r related to intelligence o r testing, a n d 57 p e rc e n t h a d given a t least o n e such speech o r lectu re to o th e r th a n a classro o m au d ien c e d u rin g th e p rev io u s tw o years. T h e m e an n u m b e r o f articles w ritten is eleven (m ed ian n u m b e r o f article s am o n g all resp o n d e n ts is three), w ith articles w ritte n for a n acad e m ic /p ro fe ssio n a l au d ien c e a b o u t five tim es m o re c o m m o n th a n tho se w ritten for a general au d ien ce. T h e m o st c o m m o n artic le to p ics p arallel th o se for areas o f research. T h e ce n tral p u rp o se o f o u r research a n d th is b o o k is to te st c e rta in p ro p o sitio n s a b o u t th e ch a n g in g p a tte rn s o f c o m m u n ic a tio n o f scientific contro v ersy to an increasingly ed u c ated public. We h y p o th esized th a t in a n u m b e r o f areas, o f w hich intelligence a n d a p titu d e te stin g is o n e, such c o m m u n ic a tio n is d isto rte d , i.e., th a t th e views o f th e relev an t e x p e rt c o m ­ m u n ity are re p o rte d in a cc u ra tely to th e a tte n tiv e p u b lic by th e elite m ed ia. T h e d isto rtio n o ccurs because o f th e changin g values a n d p erc ep tio n s o f th e in tellectu al co m m u n ity , a n d th e key role o f an elite m e d ia th a t shares such values. T h is d isto rtio n is n o t a fu n c tio n o f co n scio u s bias, b u t ra th e r o f u n d erly in g assu m p tio n s th a t define th e n a tu re o f reality to jo u rn a lis ts a n d in tellectu als alike. In som e areas, such as testing, we believe th a t th e ex p e rt c o m m u n ity has m o re o r less accep ted such d isto rtio n s as inev itab le. Since th e ir scientific findings ru n c o u n te r to a c o n v e n tio n a l w isdom w hose su p p o rte rs are q u ite p assio n ate, th ey have accep ted a tra d e o ff th a t p e rm its th e m to p u b lish th e ir findings in p ro fessional jo u rn a ls , b u t n o t for p o p u la r co n su m p tio n . U n d e r such circ u m sta n ce s th ey can c o n tin u e th e ir scientific w ork w ith o u t th e fear o f being pillo ried by th e larger c o m m u n ity an d o f b eing d ep riv ed o f g ran ts fo r research by g o v e rn m e n t agencies a n d p riv ate fo u n d atio n s. So fully have m a n y ex p e rts accep ted th is a rra n g e m e n t th a t th ey are an g ered by co l­ leagues w ith w h o m th ey agree b u t w ho p o p u la rize th e ir views a n d th u s th re a te n th e ir scientific w ork. T h u s, we m a in ta in , a society th a t prides itself o n its o p en n ess to scien ­ tific findings (w hich w ere o n ce ignored o r censo red o n ly by co n servatives) now indulges in its ow n fo rm s o f subtle ce n so rsh ip by rem o v in g th e d iscu s­ sion o f so m e scientific issues from ratio n al pu b lic d isc o u rse.9 To test these h ypo th eses o u r first task has been to su m m a riz e th e views o f th e ex p e rt c o m m u n ity as accu rately as possible. T h e d iscussion th a t fol­

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lows in th is a n d the next th ree ch ap ters, w hile in c lu d in g th e results o f o u r survey o f ex p e rt o p in io n , will necessarily be b ro a d e r in scope th a n the q u e stio n n a ire itself. T h e q u e stio n n a ire was c o n c e rn e d w ith o n ly those to p ­ ics w here th e re is c o n te n tio n w ith in th e scholarly literatu re , o r w here th e re is significant pu b lic d ebate. A full u n d e rsta n d in g o f these to p ics, however, req u ires a d iscussion o f basic testin g issues, in c lu d in g th o se for w hich th e re is a clear co n sen su s am o n g th o se w ho study tests. U n fo rtu n a tely , th e re are v irtu a lly no issues c o n c e rn in g te stin g on w hich everyone agrees. To ta k e seriously all arg u m e n ts a b o u t testin g w o u ld p u t us in a p o sitio n in w hich n e ith e r we n o r o u r read ers w ould an y lo n g er be able to d istinguish the forest from th e trees. W hile we are n o t in a p o sitio n to ju d g e th e tru th o f ex p e rt sta te m e n ts in every area, o u r read in g o f th e p sy ch o m etric literatu re ind icates th a t th e re are c e rta in p o sitio n s for w hich th e em p irical verification is so strong, a n d th e scholarly co n sen su s so over­ w h elm in g (e.g., th a t IQ is a significant p re d ic to r o f ac ad e m ic success), th a t we feel justified in sta tin g th e m as facts. T h e explicit sacrifice has been to trad e off co m p lete coverage o f th e m o st radical p o sitio n s, b o th in a n d o u t o f th e ex p e rt co m m u n ity , for clarity o f exp o sitio n . O u r fu n d a m e n ta l p re ­ m ise has been to take seriously as a scientific en terp rise a tte m p ts to u n d e r­ s ta n d a n d m e a su re in te lle c tu a l fu n c tio n in g . D e sp ite o u r a tte m p ts to rem a in objective, we realize th a t th e re are tho se to w h o m th is e n tire p ro ject is w orthless, o r w orse, because it legitim ates w h at they see as an exercise in p o litical oppression. T he D efinition of Intelligence A ccording to C yril B urt, th e w ord “ in tellig en ce,” o riginally from the L atin , w as revived by H erb ert S pencer a n d F ran cis G a lto n in th e m id n in e te e n th c e n tu ry as a scientific te rm m e an in g “ in n a te, g eneral cognitive c a p a c ity ” : in n a te, m e an in g in h e rited , a n d n o t ac q u ired th ro u g h ex p e ri­ ence; general, as in ability ap p licab le to a w ide variety o f circu m stan ces; a n d cognitive, as op p o sed to m o tiv atio n al o r e m o tio n a l.10 It was th is d efin i­ tio n B inet an d S im o n had in m in d , B urt argues, w hen th ey develo p ed th e 1905 scale. O nly later in th e c e n tu ry did th e te rm e n te r everyday language, b ec o m in g im b u e d w ith a p ro liferatio n o f m eaning. A n e x a m in a tio n o f th e w ritings o f Binet a n d S im o n reveals th a t, like m ost test d evelopers w ho have follow ed th e m , they w ere m o re co n c ern ed w ith m e a su re m e n t th a n defin itio n . T h o u g h so m e tim es sp eak in g o f ju d g ­ m e n t as th e basic facto r in intelligence, Binet a n d S im o n believed th a t sa m p lin g from a w ide variety o f m e n tal processes w ould en ab le th em to dev elop a co m p lete p ic tu re o f in tellectu al fu n ctio n in g , w ith o u t having to w o rry a b o u t w hat intelligence really was. M any o f th e m e n ta l testers sur-

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veyed in 1921 a n d 1923 ec hoed th ese se n tim e n ts: th e o re tic al q u e stio n s a b o u t th e n a tu re o f intelligence are n e ith e r as assessable, n o r as im p o r ta n t as in q u iry in to w h at it is th a t intelligence tests m easu re. Sixty years o f s u b se q u en t research o n m e n tal ab ilities has m ad e it clear th a t “ [i]ntelligence . . . is easier to m easu re th a n to define.” 11 T h ere exists to d a y an ex trem ely b ro a d sp e ctru m o f th e o ries a n d d efin itio n s o f in te l­ ligence, ran g in g from p urely biological d escrip tio n s based o n speed o f n e u ­ ral tra n sm issio n to o v erarch in g th e o ries like th a t o f H o w ard G ard n er, in w hich th e re is n o t one, b u t seven different intellig en ces en c o m p a ssin g vir­ tu a lly th e en tire realm o f h u m a n ab ilities.12 To m any, th is state o f affairs u n d e rm in e s th e e n tire te stin g en terp rise. W alter L ip p m a n n ’s 1923 assertio n th a t “ [w]e c a n n o t m easu re intelligence w hen we have n ev er defin ed it” 13 has been ec h o ed by scores o f critics in th e in te rv e n in g years. T h e resp o n se o f m a n y w ho develop a n d v alid ate in tellig en ce tests has been to show g reat deferen ce to th e o p e ra tio n a l d efin itio n th a t intelligence is w h atev er intelligence tests m e a su re .14 T h is is n o t to say th a t m o d e rn p sy c h o m etric ia n s have b lin d ly ac ce p te d so naiv e a d o ctrin e. T h e re is great c o n c e rn a m o n g th o se w ho stu d y intelligence tests a b o u t th e re la tio n sh ip o f te st results to vario u s lay a n d te ch n ic al d efin itio n s o f in tellig en ce, as w ell as w ith th e d e v e lo p m e n t o f new th e o ry a n d m eth o d o lo g y in in tellig en ce te st­ in g .15 A nd th e re is ce rta in ly n o sh o rtag e o f d efin itio n s o f in tellig en ce of­ f e r e d b y m o d e r n t h e o r e tic ia n s , a s th e S te r n b e r g a n d D e tt e r m a n sy m p o siu m d em o n strate s. T aking o p e ra tio n a lism seriously m erely shifts th e focus away fro m th e rela tio n sh ip betw een in telligence tests a n d “ in te l­ ligence” b ro ad ly defined. Instead, a d efin itio n o f in tellig en ce is deriv ed from th e v ario u s m e th o d s by w hich tests are v alid ated , in p a rtic u la r th e rela tio n sh ip te st results b ea r to som e specifically defin ed criteria. T h e o p er­ a tio n a list response w as sta te d explicitly by T. A n n e C leary a n d h er co l­ leagues o n th e APA ad hoc c o m m itte e w hen th ey claim ed th a t “th e re is a co n sen su s a m o n g psychologists as to th e k in d s o f b eh av io rs th a t are labeled in te lle c tu a l,” a n d th a t th is co n sen su s is b o th exem p lified an d defin ed by th e g reat sim ila rity o f c o n te n t o f m o d e rn intellig en ce te sts.16 A n im p o rta n t d istin c tio n m u st be m ad e a t th is p o in t. T raditionally, th e re has been a split w ith in psychology betw een th o se in te reste d p rim a rily in th e n a tu re o f intelligence a n d cognitive abilities (cognitive scientists) an d th o se w hose in te rest in intelligence is closely tied to th e ab ility to m easu re it (psychom etricians). T h is split is a p p a re n t in a c o m p a riso n o f th e 1921 a n d 1986 sy m p o sia o n th e d efin itio n o f intelligence. T h e fu n d a m e n ta l difference betw een th e tw o sym posia is in th e g rea ter e la b o ra tio n o f d efin i­ tio n in 1986. In general, th e la ter d efin itio n s are m o re d etailed a n d highly stru c tu re d , draw ing o n d a ta an d th e o ry from a v ariety o f d iscip lin es, in ­ clu d in g d ev e lo p m e n ta l psychology, neurobiology, th e stu d y o f m e n ta l re ­

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ta rd a tio n , an d artificial intelligence. T h is e la b o ra tio n derives from fu n d a ­ m e n tal changes in the way intelligence is stu d ied . In 1921, intelligence was th e p rovince o f th e m e n ta l testers, a n d sy m p o siu m p a rtic ip a n ts w ere p rin ­ cipally c o n c e rn e d w ith th e c o n s tru c t as it related to m e a su re m e n t an d p red ic tio n . In 1986, m a n y o f tho se w ho stu d y intelligence, a n d w ho c o n ­ trib u te d to th e sy m p o siu m , are n o t p sy c h o m etrician s, an d it is c o m m o n for these scientists to be m o re c o n c e rn e d w ith th e o ry th a n w ith m e asu rem en t. T h is b o o k is c o n c e rn e d w ith th e controversy over in tellig en ce a n d a p ­ titu d e testing; it is n o t in te n d e d as a survey o f co g nitive science, o r o f th e o ry o n intelligence div o rced from testin g issues. O u r d iscu ssio n o f th e n a tu re o f intelligence is, therefo re, m o re closely tied to th e rela tio n betw een th e c o n c e p t a n d its m e a su re m e n t (i.e., tra d itio n a l p sy c h o m etric co n c ern s, exem plified by th e 1921 sy m p o siu m p a rtic ip a n ts) th a n to th e m o re b ro ad ly defined c o n c ep tio n s o f cognitive th e o rists (like m an y o f th o se in th e 1986 sym p osium ). As n o te d a t th e en d o f ch a p te r 1, these n ew er co n c ep tio n s, w hich m ay radically change b o th th e th e o ry a n d m e a su re m e n t o f in te l­ ligence, have, as yet, h ad little im p a c t o n th e IQ controversy. In an y case, th e d efin itio n s p ro v id ed by th e 1921 a n d 1986 p a rtic ip a n ts are n o t radically different. H ig h er-lev e l processes, like a b s tra c t reaso n in g a n d p ro b lem solving, figure p ro m in e n tly in b o th sets o f d efin itio n s (several 1986 d efin itio n s in c lu d e executive processes, a c o m p u te r-a g e te rm refer­ rin g to h ig h er-lev el c o n tro l functions). R o b e rt S tern b erg a n d C y n th ia Berg have tallied th e vario u s a ttrib u te s o f intelligence m e n tio n e d by c o n trib ­ u to rs to the tw o sym posia, an d find th a t these tw o sets o f freq u en cies c o rrela te 0 .5 0 .17 T h e im p o rta n t d istin c tio n , fo r o u r p u rp o ses, is th a t th e c o n c ep tio n s o f intelligence m o st relev an t to th e IQ co n tro v ersy are those, fro m w hatever era, th a t are fu n d a m e n ta lly c o n c e rn e d w ith m e asu rem en t. N . J. Block a n d G erald D w o rk in in th e ir ed ited b o o k T h e IQ C ontroversy p rese n t an essay o f th e ir ow n en title d “ IQ , H eritability, a n d In e q u a lity ” th a t is p erh a p s th e best available sta te m e n t o f th e m a jo r arg u m e n ts ag ain st in te llig e n c e te s ts in th e a re a s o f th e n a tu r e o f in te llig e n c e a n d IQ h eritab ility .18 In th e first p a rt o f th e ir essay, th e a u th o rs a tta c k th e o p e ra ­ tio n a list d o ctrin e, p rim a rily for its ath eo retica l n atu re . T h ey argue th a t th e d ev e lo p m e n t o f m e an in g fu l tests o f intelligence c a n n o t p ro ceed in d e p e n ­ d en tly o f a th e o ry o f intelligence. O n e m u st have at least so m e idea o f w hat in telligence is in o rd e r to create an intelligence test. W ith o u t a theory, Block an d D w orkin claim , p sy c h o m etric ia n s have h ad to rely heavily o n in tu itiv e n o tio n s o f intelligence in the in itial co n s tru c tio n o f tests. S u b se­ q u e n t v alid atio n has p rim a rily consisted o f c o rre la tio n w ith previously accep ted tests. (T his m ay a c c o u n t for C leary et al.’s “co nsensus.” ) T h u s, th e h isto rical d ev e lo p m e n t o f intelligence testin g has been a “ technological, n o t a sc ie n tific p ro ce ss.” 19 T h e in tu itiv e n o tio n s o n w h ich th is te c h ­

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nological process is based m ig h t b ea r little rese m b la n ce to w h at in tellig en ce really is (if th e re w ere a unified theory). In a tru e scientific process, m e a ­ su re m e n t an d th e o ry m u st progress together. (T erm an m a d e essentially th e sam e p o in t in 1916.)20 In th e absence o f theory, tech n o lo g ical progress p ro d u ce s b e tte r an d b e tte r ways to m easu re q u a n titie s w hose rela tio n sh ip to “ in te llig en ce” is unk n o w n . O p eratio n alists m ay offer som e defense by p o in tin g o u t th a t it is n o t th e rela tio n sh ip betw een test scores a n d “ in te llig en ce” th a t is im p o rta n t. T h a t rela tio n sh ip is defined by th e p rin cip al te n e t o f o p era tio n alism . W h a t is im p o rta n t is how test scores relate to c e rta in o th e r crite ria like success in school a n d in th e jo b m ark et. As T erm a n w arn ed in 1921, “ th e valid ity o f a new test sh o u ld n o t be ju d g e d en tirely by its co rre la tio n w ith existing tests, how ever good these m ay be. T h ere m u st be c o n tin u e d search for useful o u tsid e criteria.”21 B ut o n e m u st still have som e in d e p e n d e n t n o tio n o f intelligence by w hich to d ecide th e usefulness o f an e x tern al criterio n . T erm an co n tin u es, “ O n th e o th e r h an d , in o u r an x iety to escape th e evils o f a closed system we m u st g u ard against in d isc rim in a te a n d ill-c o n sid e re d use o f o u tsid e criteria. To c o n d e m n an intelligen ce te st b ecau se it yields low c o rre la tio n s w ith success as a m ill h a n d o r stree tc ar m o to rm a n is an e x a m ­ ple o f th is erro r."22 O bviously, being a good m o to rm a n req u ires little o f w h at T erm an co n sid ers intelligence. T h e p o in t is, s o m e in d e p e n d e n t n o ­ tio n o f intelligence is necessary in o rd e r to d ecide w h eth e r a test th a t p red icts success as a m ill h a n d o r stree tc ar m o to rm a n sh o u ld be co n sid ered a good test o f intelligence. T h a t such a test m ig h t c o rre la te p o o rly w ith o th e r intelligence tests is in a d e q u a te g ro u n d s fo r rejectio n unless th e re are in d e p e n d e n t reasons for believing th e o th e r tests are b e tte r m easu res o f intelligence. In th e end, th e real conflict betw een tho se w h o criticize th e ath eo retica l n a tu re o f intelligence testin g a n d te stin g ’s su p p o rte rs co m es d ow n to how m u c h fuzziness in th e d efin itio n o f intelligence is to be to le rate d . C ritics p o in t to th e lack o f a unified th e o ry o r u n iversally agreed u p o n d efin itio n o f intelligence. D efenders seem c o n te n t w ith th e high c o rre la tio n betw een scores on d isp a ra te tests, as well as th e stro n g rela tio n sh ip betw een test results an d alm o st an y c o m m o n sense c riterio n o f intelligence. U n fo rtu n a tely , m a n y stro n g believers in th e valid ity o f in telligence tests use th e w ord “ in tellig en ce” ra th e r m o re freely th a n th ey should. A u th o rs will o ften discuss b o th th e te ch n ic al an d in tu itiv e d efin itio n s o f in telligence in th e sam e d o c u m e n t, a n d th e reference o f an y p a rtic u la r ap p e a ra n c e o f th e w ord is o ften am b ig u o u s. T h e im p re ssio n given by su ch w ritings is m isleading: th a t o n e ’s in tu itiv e idea o f intelligence, a n d th e results o f in te l­ ligence tests, are sy n o n y m o u s. Intelligence is a fuzzy c o n c ep t th a t req u ires a fuzzy d efin itio n . A s D o u g ­

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las D e tte rm a n p u t it in c o m p a rin g th e 1986 sy m p o siu m resu lts to those from 1921: Though the definitions provided by this symposium may be more refined, substantial disagreement on a single definition still abounds. It is probably foolish to expect this symposium, or even one held 65 years from now, to come to a unanim ous conclusion. A concept as complex as intelligence prob­ ably cannot be captured by a single definition without gross oversimplifica­ tion.23 1. It has been a rgued th a t there is a consensus a m o n g p sych o lo g ists a n d educators as to th e k in d s o f behaviors th a t are la b eled "intelligent." D o yo u agree or disagree that there is such a consensus? R e sp o n d en ts are in clin ed to agree th a t th e re is a co n sen su s. F ifty -th re e p e rc e n t eith er so m ew h at o r strongly agree, c o m p a re d to 39.5 p erc en t w ho disagree in som e m an n er. T h e re m a in in g 7.5 p erc en t d id n o t resp o n d to th e q u estio n . T hese results d o n o t d e m o n stra te , o f course, th a t a co n sen su s actu ally exists (q u estio n 3 is d irec ted at th a t issue), b u t it is th e case th a t m o st o f th e ex p erts in o u r sam p le have th e p erc ep tio n th a t th ey are w orking w ith in a co m m o n ly accep ted fram ew ork. 2. D o yo u believe that, on th e whole, th e d evelopm en t o f in telligence tests h a s p roceeded in th e co n text o f an ad eq u a te th eo ry o f intelligence? O u r ex p e rt sa m p le is p re d o m in a n tly in ag re em e n t w ith th is fu n d a m e n ta l critiq u e. F ifty -fo u r p erc en t o f tho se surveyed answ er “ N o ” to th is q u e s­ tio n , co m p ared to 34 p erc en t w ho answ er “ Yes.” T h e rem a in in g 12 p erc en t d o n o t respond. T h e o b v io u s fo llo w -u p q u estio n , w hich, u n fo rtu n a te ly , we d id n o t ask, is “ D oes th is m ak e an y difference to th e valid ity o f th e tests?” To Block a n d D w orkin, the lack o f a unified th e o ry o f intelligence severely red u ces th e validity an d usefulness o f intelligence tests. M o st ex p erts in o u r sa m p le agree w ith th e p rem ise o f th is a rg u m e n t. R e su lts fro m th e re ­ m a in d e r o f th e q u e stio n n a ire , however, d e m o n stra te th a t th ese ex p e rts do n o t share Block an d D w o rk in ’s pessim istic co n c lu sio n a b o u t tests. 3. Im p o rta n t elem en ts o f intelligence. R e sp o n d en ts w ere asked to check all b ehavioral d escrip to rs listed (th ere w ere th irte e n , a n d space for w riting in o thers) th a t th ey believe to be an im p o rta n t elem e n t o f intelligence. T h is q u estio n a tte m p ts to assess directly th e n a tu re o f co n sen su s a b o u t th e d efin itio n o f intelligence. R esults are show n in Table 2.3. R esponse rate w as 93 p ercen t. D escrip-

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The IQ Controversy TABLE 2.3 Important Elements of Intelligence

Descriptor Abstract thinking or reasoning • Problem solving ability Capacity to acquire knowledge Memory Adaptation to one’s environm ent Mental speed Linguistic competence Mathematical competence General knowledge Creativity Sensory acuity Goal-directedness Achievement motivation

% of Respondents Checking as Important 99.3 97.7 96 80.5 77.2 71.7 71 67.9 62.4 59.6 24.4 24 18.9

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to rs fall in to o n e o f th ree w ell-d e fin ed categories: th o se fo r w hich th e re is n e a r u n a n im ity (greater th a n 96 p erc en t a g re em e n t am o n g th o se w ho a n ­ sw ered th e q u e stio n )— “a b stra c t th in k in g o r rea so n in g ,” “ th e ca p ac ity to a c q u ire know ledge,” a n d “ p ro b lem solving ab ility ” ; th o se ch eck ed by a m ajo rity o f resp o n d e n ts (6 0 -8 0 p erc en t)— “a d a p ta tio n to o n e ’s e n v iro n ­ m e n t,” “creativity,” “general know ledge,” “ ling u istic c o m p e te n c e ,” “ m a th ­ e m atical co m p e te n c e ,” “ m e m o ry ,” an d “ m e n tal sp eed ” ; a n d th o se rarely checked (less th a n 25 p e rc e n t)— “ac h ie v e m e n t m o tiv a tio n ,” “g o a l-d ire c te d n ess,” a n d “ sensory acuity.” T h e m o st c o m m o n ly ad d e d b eh av io ral d e­ sc rip to rs are “social o r in te rp e rso n a l c o m p e te n c e ,” “ sp atial ability,” an d “ integ rativ e capacity,” th o u g h n o n e o f th ese is ad d ed by m o re th a n 2 per­ c e n t o f resp o n d en ts. T h ese results sh o u ld n o t be ta k en as p ro v id in g a d efin itio n o f in te l­ ligence. A list o f tra its is n o t a rigorous scientific d efin itio n , a n d it ce rtain ly is n 't a unified theory. N onetheless, tw o im p o rta n t p o in ts can be m ade. F irst, as in prev io u s surveys already cited, th e re is co n sid erab le disag ree­ m e n t a b o u t th e b rea d th o f th e d efin itio n , such th a t, for ex am p le, a su b sta n ­ tial m in o rity o f re sp o n d e n ts disagree th a t m a th e m a tic a l co m p ete n ce an d creativ ity sh o u ld be in clu d ed . It is these so rts o f d isag reem en ts th a t fuel d e b a te a b o u t th e n a tu re o f cognitive abilities. A cc o m p an y in g th e d isa g re em en t a b o u t th e scope o f th e d efin itio n o f intelligence is very stro n g ag re em e n t at its core. It can reaso n ab ly be c o n ­ clu d ed th a t w hen different psychologists an d ed u c ato rs use th e te rm “ in te l­ ligence” they are b asically referrin g to th e sam e co n cep t, having to d o w ith th e cap acity to le arn an d w ith m o re co m p lex co g n itiv e task s like ab stra ct reaso n in g an d p ro b lem solving, a n d th a t they w ould g enerally exclude

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p u rely m o tiv atio n al an d sensory abilities from th is d efin itio n . T hese sam e th rea d s ru n th ro u g h b o th th e 1921 an d 1986 sym posia. In m an y ways, T e rm a n ’s 1921 d efin itio n o f intelligence as a b stra c t th in k in g rem a in s at th e h e a rt o f c u rre n t th o u g h t a b o u t intelligence. A p ro p o s o f o u r ea rlier d iscussion o f th e d istin c tio n betw een cognitive scien tists an d p sy c h o m etrician s, th e survey sam ple was ch o sen to reflect ex p ertise a b o u t a b ro a d range o f testin g issues, a n d th erefo re in clu d es a large p ro p o rtio n o f p sy ch o m etrician s. T h ere are, however, m a n y o th e r d is­ cip lin es rep resen ted , including, for exam ple, d e v e lo p m e n ta l psychologists an d cognitive scientists (m em b ers o f th e C ognitive S cience Society), w ho m ig h t be expected to b rin g very different perspectives to th e q u estio n o f the n a tu re o f intelligence. It is te stim o n y to th e g enerality o f th e resu lts in T able 2.3 th a t c o m p a riso n o f responses betw een th e v ario u s p rim a ry an d se co n d a ry g roups in th e sam p le does n o t reveal a greater n u m b e r o f sta tis­ tically significant differences o n an y o f th e elem e n ts o f in telligence th a n w ould be expected by chance. T h e results o f th e first th ree q u estio n s on th e n a tu re o f intelligence p rese n t a m ixed p ic tu re o f th e c u rre n t psychological consensus. T h ere ap p e ars to be basic ag re em e n t a b o u t th e m o st im p o rta n t elem e n ts o f in te l­ ligence, b u t co n sid erab le d issension a b o u t th e details. T h ese d a ta su p p o rt th e m a jo rity o p in io n th a t intelligence tests have n o t been th e p ro d u c ts o f unified a n d co m p re h en siv e theo rizin g . It is n o t tru e, however, th a t th e d ev e lo p m e n t o f in tellig en ce tests has p ro ceed ed in th e absence o f a n y theory. B esides th e im p licit th e o ry th a t m u st ac c o m p a n y all test d ev e lo p m e n t, explicit th e o ries o f intelligence, b o th old an d new, a b o u n d , a n d th e re are m an y tests th a t have been d e ­ v elo p ed in c o n n e c tio n to p a rtic u la r th e o rie s.24 C ritics like Block a n d D w o rkin argue th a t th e p iecem eal ap p ro a ch is n o t sufficient, a n d th a t for p sy ch o m etrics to beco m e a tru e science tests m u st dev elo p h a n d - in - h a n d w ith a unified theory. In response, m an y p ro p o n e n ts o f testin g p o in t to th e su b stan tia l degree o f in te rc o rre la tio n betw een p e rfo rm a n c e o n all tests o f m e n tal ability, regardless o f th e ir th e o re tic al origins. T h e a rg u m e n t is m ad e th a t, w ith o r w ith o u t a p ro p er theory, all o f these tests seem to be m e asu r­ ing th e sam e basic abilities, loosely defined as “ intelligence.” W hat Intelligence T ests M easure 4. Im p o rta n t elem en ts o f intelligence not m easured. As a d irect assessm en t o f th e ability o f intelligence tests to m easu re “ in tellig en ce,” we asked ex p e rts a b o u t th e fit betw een th e tests an d th e ir ow n d efin itio n o f intelligence. R e sp o n d en ts w ere asked to ch eck each o f th e

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b ehavioral d escrip to rs th a t they believe to be an im p o rta n t elem e n t o f intelligence (from th e p reced in g q uestion), b u t th a t th ey d o n o t feel is ad e q u ately m e asu red by th e m o st c o m m o n ly used intelligence tests. T h e results o f th is q u e stio n are given in Table 2.4. (N o te th a t th e p e rc e n t­ ages given in th is tab le are draw n on ly from th o se w h o had prev io u sly checked th e d e sc rip to r as an im p o rta n t elem e n t o f intelligence, a n d n o t from the e n tire sam p le.) R esponse rate w as 87 p ercen t. O n th e w hole, resp o n d e n ts seem to believe th a t intelligence tests are d o in g a g o o d jo b m easu rin g intelligence, as th ey w ould define it. O f th e te n b eh av io ral d e ­ sc rip to rs checked as im p o rta n t elem e n ts by m o re th a n 60 p erc en t o f re­ sp o n d e n ts, o nly tw o, “ a d a p ta tio n to o n e ’s e n v iro n m e n t” a n d “ creativ ity ,” are checked by a m a jo rity as n o t ad e q u ately m easu red , a n d o n ly o n e other, “ cap acity to ac q u ire know ledge,” is checked by m o re th a n 20 p ercen t. T h e “a d a p ta tio n to e n v iro n m e n t” resu lt reflects th e c o m m o n criticism th a t tests a re m u c h b e tte r a t m e a su rin g tra its im p o r ta n t to success in school th a n general life skills. It is also co n siste n t w ith results fro m earlier surveys o f e x p e rt o p in io n in w hich th e re w as a co n sen su s a b o u t in telligence as an ad a p tiv e skill, b u t d isa g re em en t a b o u t th e v ariety o f life c irc u m ­ stances u n d e r w hich a d a p ta tio n sh o u ld be called in tellig en t. Sim ilarly, th e “ cre a tiv ity ” finding is n o t su rp risin g in light o f th e p o o r co rre la tio n b e­ tw een tests o f intelligence a n d tests o f creativity. T h a t tests o f cre ativ ity are th em selves p oorly in te rc o rre la te d is evid en ce th a t b eh av io ral scien tists are u n su re o f w h at creativ ity consists, o r w here it fits in th e co n stellatio n o f cognitive ab ilities.25 M ore tro u b le so m e for su p p o rte rs o f te stin g is th a t 42 p e rc e n t o f th o se w ho believe “cap acity to ac q u ire know ledge” is an im p o rta n t e le m e n t o f intelligence, w hich in clu d es v irtu ally all resp o n d e n ts, d o n o t believe it is a d e q u ately m e asu red by intelligence tests. As w ith th e p rev io u s q u estio n , th e results o f q u estio n 4 are m o re m e an in g fu lly in te rp re te d at a very g en ­ eral level— th a t ex p e rts believe intelligence tests, w hile far from perfect, are for th e m o st p a rt m easu rin g w h at th ey sh o u ld be m e a su rin g — th a n a t th e level o f specific b ehavioral te rm s, w here am b ig u ities a b o u n d . S om e d istin c tio n s in te rm in o lo g y a re w a rra n te d a t th is p o in t. We will use th e te rm s “ IQ te st,” “ intelligence te st,” a n d “te st o f g eneral m e n ta l a b ility ” interchangeably. A s n o te d , IQ , w hich sta n d s fo r in tellig en ce q u o ­ tie n t, w as first defined by th e G e rm a n psychologist S tern as th e ra tio o f m e n ta l age (tested age o n an ag e -g ra d ed intellig en ce test) to ch ro n o lo g ical age. In o rd e r to e lim in a te n o n lin e a ritie s resu ltin g fro m changes in c h ro ­ nological age (a s ix -y e a r-o ld w hose m e n tal age is re ta rd e d tw o years will have a m u c h low er IQ th a n a tw e lv e -y e a r-o ld w ith th e sam e degree o f reta rd a tio n ), IQ is now defined as having a m e an o f 100 in each age group, an d a sta n d a rd d e v iatio n o f e ith e r 15 o r 16 (d ep en d in g o n th e test). T h u s,

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TABLE 2.4 Important Elements of Intelligence Not Adequately Measured by Intelligence Tests Descriptor Abstract thinking or reasoning Problem solving ability Capacity to acquire knowledge Memory Adaptation to one’s environment Mental speed Linguistic competence Mathematical competence General knowledge Creativity Sensory acuity Goal-directedness Achievement motivation

% of Respondents“ Checking as Not Adequately Measured 19.9 27.3 42.2 12.7 75.3 12.8 14 12.1 10.7 88.3 57.7 64.1 71.7

“R e s p o n d e n ts in c lu d e o n ly th o se w h o h a d p re v io u sly in d ic a te d th a t d e sc rip to r w as a n im p o rta n t e le m e n t o f in telligence.

an e ig h t-y e a r-o ld w hose score is o n e sta n d a rd d ev iatio n above th e e ig h ty e a r-o ld m e an o n th e S ta n fo rd -B in e t test has an IQ o f 116. T h is m e th o d o f ca lc u latin g IQ necessitates p ro p e r sta n d a rd iz a tio n for th e p o p u la tio n being tested. In telligence tests m ay be d istin g u ish e d from a p titu d e tests. O n e tr a d i­ tio n . w hich we will n o t honor, is to call all g ro u p tests o f general ability a p titu d e tests, reserving th e te rm s intelligence an d IQ test for in d iv id u ally a d m in iste re d ex a m in a tio n s. T h e m o re critical d istin c tio n is th a t ap titu d e tests are usually fairly h o m o g e n eo u s surveys o f specific abilities, su ch as m a th em atical o r m usical skill. Intelligence tests, on th e o th e r h an d , m e a ­ sure a w ider variety o f skills necessary for ac ad e m ic success. Intelligence tests may, eith er th ro u g h design o r su b se q u en t facto r analysis, yield, in a d d itio n to a m easu re o f general intelligence, subscores c o rresp o n d in g to m o re specific abilities like verbal co m p re h e n sio n an d n u m e rical reasoning. Such tests are q u ite sim ila r to m u ltip le a p titu d e b atteries, w hich consist o f a b ro ad range o f specific a p titu d e tests. In th e d iscussion th a t follows, intelligence tests are trea ted as tests o f general co gnitive ap titu d e . A d d i­ tionally, we will use “ IQ " as a s h o rth a n d for scores on all intelligence an d general ap titu d e tests. A g reat deal o f co n fu sio n has been g en erated in th e p o p u la r literatu re c o n c e rn in g th e difference betw een intelligence o r a p titu d e tests a n d tests o f sch o lastic ach iev em en t. M uch o f th is co n fu sio n m ay be w a rra n te d by th e fact th a t scores on intelligence an d ach ie v em e n t tests are highly co rrelated . N o n etheless, a d istin c tio n m ay be m ade, at least at th e level o f in te n tio n s.

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A ch ie v em en t tests are in te n d e d to asce rta in th e degree to w hich an in d iv id ­ ual has m astered a c e rta in body o f know ledge. S uch tests are g en erally ev a lu ated fo r c o n te n t validity (th e degree to w hich th e q u e stio n s actu ally c o n ta c t th e body o f know ledge in q u e s tio n — see below). In tellig en ce a n d a p titu d e tests are designed to m easu re th e e x te n t o f c e rta in ab ilities o r skills possessed by th e resp o n d e n t th a t are pred ictiv e o f success in fu tu re en d eav ­ ors, m o st n o ta b ly academ ics. In a d d itio n , intellig en ce tests u su ally m e a ­ su re a m u c h b ro a d e r ran g e o f b eh a v io rs th a n a c h ie v e m e n t tests, a n d req u ire know ledge le a rn e d in th e m o re d ista n t p ast.26 A t o n e level, a ll cognitive tests are tests o f ach ie v em e n t. A n ew b o rn in fa n t can n o m o re solve a block design p ro b lem o n an in tellig en ce test th a n it can n am e th e state ca p ita ls o n a geograp h y ac h ie v e m e n t test. T h e necessary skills in bo th cases m u st be le arn ed . T h e im p o rta n t d istin c tio n is betw een th o se skills a n d abilities th o u g h t to be ac q u ired over a lifetim e, a n d to be ap p lica b le to a w ide variety o f cognitiv e tasks, a n d specific b o d ies o f know ledge generally a c q u ire d in a classroom setting. It m ay be p o in te d o u t, however, th a t th is d istin c tio n often does n o t h o ld in p ractice, as, for exam ple, in th e u b iq u ito u s v o ca b u la ry q u e stio n s o n in tellig en ce tests. Test m a k ers m ay resp o n d : H ow b e tte r to te st an ability like verbal c o m p re h e n ­ sion th a n to ask v o ca b u la ry q u estio n s? T h e a ssu m p tio n is th a t all test ta k ers will have h ad sufficient ex posure to th e rele v an t e n v iro n m e n ta l stim ­ uli for differences in ac q u ired v o ca b u la ry to ac cu rately reflect differences in verbal co m p re h e n sio n . N o n ex p o su re is th o u g h t to in tro d u c e e rro r d is­ trib u te d ra n d o m ly across resp o n d e n ts. If these a s su m p tio n s are in c o rrec t, th e test will be biased (see below). In fact, a p titu d e a n d ach ie v em e n t tests often look very sim ilar. T h e g rea ter th e e n v iro n m e n ta l ex p erien ce te st ta k ers are assu m ed to share, th e m o re a p titu d e tests will look like a c h ie v em e n t tests. T h e m o st n o ta b le ex am p le o f th is p h e n o m e n o n , a n d o n e th a t has cau sed a g reat deal o f contro v ersy in rec en t years, is th e S cholastic A p titu d e Test (SAT). D espite th e te st’s title, th e E d u ca tio n a l T esting Service (ET S) has b ec o m e q u ite w ary o f calling th e SAT a test o f ac ad e m ic a p titu d e , stressing in stea d “ d e­ veloped abilities.” T h is has p u t th e ETS in th e stran g e p o sitio n o f sim u l­ ta n e o u s ly a rg u in g th a t its te st m e a su re s d e v e lo p e d a b ilitie s, b u t th a t co ach in g p ro g ra m s aim ed at raising SAT scores d o n ’t w o rk .27 (See C h a p te r 5 for m o re on th e d eb a te over SAT coaching.) T h e SAT d o es co n sist largely o f q u e stio n s ta p p in g specific know ledge a b o u t v ocabulary, algebra, an d geom etry. N onetheless, to th e ex ten t th a t te st ta k ers have been exposed to sim ila r high school c u rric u la , th e SAT will w ork like an IQ o r a p titu d e test in th e p o p u la tio n being tested. N o d o u b t th is c o rre la tio n w ould b reak dow n if th e test p o p u la tio n consisted o f m a n y test ta k ers w ho h ad n o t c o m p leted tw o years o f high school.

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A n n e A nastasi has d escribed a “C o n tin u u m o f E x p erien tial Specificity” am o n g ab ility tests. O n th e highly specific en d o f th e c o n tin u u m are co u rse -o rie n te d ach ie v em e n t tests tied to p a rtic u la r acad em ic in stru c tio n . O n th e highly general en d are so -c a lle d “c u ltu r e - fa ir ” tests (see C h a p te r 4) such as th e R avens Progressive M atrices, consistin g o f ab stra ct se rie s-co m p letio n p ro b lem s involving little o r no language o r o th e r c u ltu rally -sp e cific know ledge. V erb al-ty p e intelligence a n d a p titu d e tests fall in th e m id d le o f th is c o n tin u u m .28 R o b e rt G o rd o n h as n o te d th a t m u ch o f th e high c o rre la tio n betw een a p titu d e o r intelligence an d ach ie v em e n t tests can be ac c o u n te d for by th e fact th a t m o st te st ta k ers have had eq u iv ale n t ex posu re to relev an t stim uli: When all individuals have had more or less equal exposure to school instruc­ tion, even a highly specific achievement test can function approximately as an aptitude or intelligence test in measuring individual differences . . . The greater sensitivity of properly constructed achievement tests than o flQ tests to instruction is seldom demonstrated by giving them, along with intelligence tests, to individuals half of whom have had no instructions at all in the subject at hand. This would be wasteful and expensive, but it would break down the correlation between the two type of tests.29 A n o th e r reason intelligence a n d ach ie v em e n t tests c o rrela te so well is th a t intelligence tests are designed th a t way. Intelligence tests are valid ated to a large degree by th e ir ability to p red ict ac ad e m ic success. Such success in clu d es grades, te ac h er ev alu atio n s, an d scores o n ach ie v em e n t tests. T h e logic b eh in d th is strategy is th a t o n e sho u ld req u ire a test designed to m easu re c e rta in abilities necessary for scholastic ach ie v em e n t to p red ict scores on scholastic a c h ie v em e n t tests. D ifficulties arise, ac co rd in g to cer­ ta in critics, w hen th e high c o rre la tio n betw een intelligence an d ach iev e­ m e n t te sts is used to argue th a t in te llig en c e tests m e a su re im p o r ta n t skills.30 T hese arg u m e n ts hold little w eight, they claim , becau se th e tests w ere designed to p ro d u ce such co rrelatio n s. S uch criticism s are n o t w h at drives th e a p titu d e -a c h ie v e m e n t d eb ate, however. At th e h e a rt o f th is controversy is th e p erc ep tio n th a t an in te l­ ligence o r a p titu d e test score is a relatively p e rm a n e n t featu re o f th e in d i­ v id u a l. T h e d e s ire to b lu r th e a p titu d e - a c h ie v e m e n t d is tin c tio n by claim in g th a t intelligence an d a p titu d e tests m easu re n o th in g b u t “ ac­ q u ire d kn o w led g e” is an a tte m p t to red u c e th e p o te n tia l stig m atizin g effects o f th e IQ a n d to em p h asize th e plasticity o f intelligence. (T hese claim s are also freq u en tly m a d e in th e c o n te x t o f a cu ltu ral bias arg u m en t: sin ce in te llig en ce te sts are p rim a rily m e a su re s o f e n v iro n m e n t-s p e c ific know ledge, te st ta k ers w ith m o re expo su re to th e w hite m id d le -c la ss e n ­ v iro n m e n t for w hich th e tests are w eighted are a t an u n fa ir ad v an tag e.) It is

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an o u tgrow th o f the e n v iro n m e n ta lism o f th e 1960s an d 70s. As an a tte m p t to alleviate stig m atiza tio n a n d grief, th is red efin itio n is co m m en d a b le , b u t a t th e scientific level it is based o n a false d istin ctio n . T h e ac q u ired , a n d th erefo re m alleable, know ledge it is claim ed intelligence an d ap titu d e tests are actu ally m easu rin g is c o n tra ste d w ith th e in n a te, an d th erefo re fixed, skills a n d abilities intelligence a n d a p titu d e tests are su p p o sed to be m e a ­ suring. In fact, as will be m a d e clear in th e n ext chapter, all skills, abilities, an d know ledge are d e p e n d e n t on b oth genes an d en v iro n m e n t, an d all are m o d ifia b le th ro u g h e n v ir o n m e n ta l c h a n g e . T h a t th e e n v ir o n m e n ta l change necessary to raise IQ significantly is m u c h g rea ter th a n th a t need ed to raise o n e ’s score on a F ren ch language ach ie v em e n t test is an im p o rta n t d istin ctio n , an d c a n n o t be glossed over by argu in g th a t all tests m easu re ac q u ired know ledge. 5. C o m p a re d to success on a chievem ent tests, does success on intelligence tests a m o n g A m eric a n test ta k ers g enerally d ep e n d less, m ore, or a bout th e sa m e a m o u n t on acquired know ledge? T his q u estio n is d elib erately am b ig u o u s, a n d was in c lu d ed becau se arg u ­ m e n ts a b o u t testin g are co m m o n ly p h rased th is way in th e p o p u la r press. O ne can m a in ta in th a t “ac q u ired know ledge” is a n y th in g n o t directly co ­ d ed in to th e genes, in w hich case all behavioral in d ices m easu re it to th e sam e degree. T h e p o p u la r c o n c ep tio n seem s to be, however, th a t “ ac q u ired k now ledge” refers n o t to ac q u ired skills a n d abilities, b u t to specific pieces o f in fo rm a tio n , an d is to be c o n tra ste d w ith “ in n a te ab ilities” ; th e n o tio n th a t genes a n d e n v iro n m e n t are b oth necessary to th e d ev e lo p m e n t o f all aspects o f b eh av io r seem s to have been lost in pu b lic d iscussion. By w hatev er d efin itio n th ey m ay be using, ex p e rts te n d to disagree th a t intelligence a n d ach ie v em e n t tests are alike in th e ir d ep e n d en c y o n a c ­ q u ired know ledge. F ifty -n in e p erc en t believe th a t intelligence tests d ep e n d so m ew h at o r m u c h less o n ac q u ired know ledge, 25 p erc en t say it is a b o u t th e sam e, an d 7 p erc en t say ac q u ired know ledge is m o re im p o rta n t to intelligence tests th a n to ac h ie v em e n t tests. E ight p erc en t d id n o t an sw er th e q u estio n . B ecause o f th e am biguity, these results are o n ly m ean in g fu l as a response to sim ilarly w orded, a n d equ ally confu sin g , arg u m en ts. In th e design a n d ev a lu a tio n o f intelligence tests th e re are tw o issues o f p rim a ry im p o rta n c e ; reliability an d validity. R eliab ility refers to th e co n sis­ ten cy o f test scores w hen an in d iv id u al is given th e sam e o r sim ila r item s u n d e r sim ila r test c o n d itio n s. It is g enerally m e asu red in o n e o f th ree ways: by a d m in iste rin g th e sam e test on tw o differen t o ccasio n s (te st-re te st, also k now n as stability), by a d m in iste rin g tw o fo rm s o f th e sam e test o n e ith e r th e sam e o r different occasions (a lte rn a tiv e form ), o r by co m p a rin g scores

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on d ifferent ite m s w ith in th e sam e ad m in istra tio n o f a test (sp lit-h a lf, o r in te rn a l consistency). (C onceptually, reliability an d stab ility are d istin ct, stab ility referrin g to th e consistency o f test scores over tim e. S tability co ­ efficients are often calcu lated afte r th e u n reliab ility o f th e te st— even id e n ­ tical tests given to th e sam e perso n at a single test a d m in is tra tio n will n o t p ro d u ce identical scores— has been co rrec ted for. In p ractice, tests w ith high reliability also te n d to be highly stab le.)31 T h e m o st co m m o n n u m e r­ ical e stim a te o f reliability is th e reliability coefficient, th e co rrela tio n coeffi­ c ie n t b e tw e e n th e te s t s c o re s b e in g c o m p a r e d . F o r i n d i v i d u a l l y a d m in iste re d in tellig en ce tests, reliab ility co e fficien ts rarely are below 0 .8 0 .32 T h e im p o rta n c e o f reliability in th e e v a lu a tio n o f intelligence tests is o bvious. R egardless o f w h at th e test is m easu rin g , on e w ould have little co n fidence in a scale w hose e stim a tes varied w idely u n d e r highly sim ilar te stin g circu m stan ces. Such v aria tio n is usually a ttrib u te d to m e a su re m e n t error, a n d one o f th e goals in th e d ev e lo p m e n t o f an y scaling in s tru m e n t is to p ro d u ce as e rro r-fre e m e a su re m e n t as possible. In terp retin g in tra in d iv id u a l v aria tio n s in te st scores as m e a su re m e n t e rro r assum es th a t w hatev er is being m e asu red is itself q u ite stable. T h is a s su m p tio n is p ro b ab ly co rrec t for th e circ u m sta n ce s u n d e r w hich m o st reliability (o r stability) coefficients are calcu lated , th a t is, w ith in th e sam e, o r tw o closely spaced, test sessions. W hen the sam e in d iv id u al is tested over longer p eriods o f tim e, test scores are n o t always very stable. S om e o f th is in stab ility is a fu n ctio n o f m e a su re m e n t error, b u t gen etic a n d e n v iro n ­ m e n tal factors p ro d u c in g real changes in intelligence are also believed to be at w ork. IQ scores are n o rm referenced; IQ is c o m p u te d by c o m p a rin g an in d iv id u a l’s score to tho se o f o th e rs in th e sam e age group. C hanges in IQ w ith age th erefo re reflect ch anges in an in d iv id u a l’s ran k in g ; th a t ab so lu te level o f intelligence increases w ith age has already been co n tro lled for. P rio r to age three, scores o n tests o f m en tal d e v e lo p m e n t are q u ite u n sta ­ ble an d are usually ra th e r p o o r p red ic to rs o f a d u lt IQ .33 A t fo u r o r five, scores begin to beco m e m o re c o n siste n t an d are fo u n d to c o rrela te betw een 0 .50 a n d 0.70 w ith ad u lt IQ .34 T h e highest levels o f stab ility are o b ta in ed a fter age eight, w hen c o rre la tio n s betw een rep eated in telligence tests given over q u ite large tim e intervals, co rrec ted for unreliability, are betw een 0.90 an d 1.0.35 Jen sen co m p ares these changing p a tte rn s o f c o rre la tio n s to those asso ciated w ith changes in height, body w eight, an d physical stren g th , an d co n clu d es, “ alth o u g h th e IQ is ce rtain ly n o t ‘c o n s ta n t,’ it seem s safe to say th a t u n d e r n o rm a l en v iro n m e n ta l c o n d itio n s it is at least as stable as d e­ v elo p m en tal ch a racteristics o f a strictly physical n atu re .” 36

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6. H o w stable is th e a ttribute(s) bein g m e a su re d b y intelligence tests, co m p a re d to a p u re ly p h y sic a l characteristic such as height, when each is ex p re ssed relative to th e p o p u la tio n m ean? Intelligence, as m e asu red by intelligence tests, is view ed as less stable th a n height. S ev en ty -sev en p erc en t o f ex p e rts surveyed say intelligence is so m e w h at o r m u c h less stable, 11 p erc en t say it is eq u ally stable, a n d o n ly 2 p erc en t in d ic ate it is so m ew h at o r m u c h m o re stable. Ten p erc en t d id n o t respond. T h ere is an in te rp re ta tio n a l p ro b lem w ith th is q u estio n , as m a n y re­ sp o n d e n ts in d ic ated th a t th ey w ere n o t sure a t w h at age to m ak e th e c o m ­ p ariso n . T h e p h rase “ relative to th e p o p u la tio n m e a n ” w as in te n d e d to refer to th e sa m e -a g e p o p u la tio n m e an , as is sta n d a rd p ractice in th e scoring o f intelligence tests, a n d th u s th e q u e stio n refers to th e e n tire life span. It is clear, however, th a t m a n y re sp o n d e n ts w ere n o t an sw erin g th e q u estio n we w ere asking. O f g rea ter relevance to th e q u e stio n o f w h at in tellig en ce tests m easu re is th e issue o f validity. A n n e A nastasi, in h e r sta n d a rd te x t P sychological T esting, identifies th ree basic fo rm s o f validity: c o n te n t, criterio n , a n d co n stru c t. “C o n te n t v alid atio n involves essentially th e sy stem atic e x a m ­ in a tio n o f th e test c o n te n t to d e te rm in e w h eth e r it covers a rep resen tativ e sam ple o f th e b eh a v io r d o m a in to be m e asu red .”37 T h is fo rm o f valid ity is o f g rea ter relevance to tests o f scholastic ac h ie v e m e n t an d specific a p ­ titu d e s th a n to general intelligence tests. W hen o n e w ishes to m easu re m a th e m a tic a l ac h ie v em e n t, for exam ple, th e relev an t b eh av io rs (b o d y o f know ledge) are clearly defined, an d th e test m ay be ev a lu ated ag ain st th o se behaviors. In tellig en t beh av io r is n o t so easily defined (as we have seen), a n d tests o f intelligence m u st be c o m p a re d e ith e r to som e e x tern al criteria th o u g h t to be related to intelligence, o r to so m e th e o re tic al co n stru c t. “ C rite rio n -re la te d v alid atio n p ro ced u res in d ic ate th e effectiveness o f a test in p red ictin g an in d iv id u a l’s beh av io r in specified situ atio n s.” 38 C rite­ rio n validity rep rese n ts an im p o rta n t, an d for th o se w h o d isc o u n t existing th e o ries o f intelligence, th e only, m e th o d o f ev a lu a tin g tests o f g eneral intelligence. As no ted , IQ is q u ite pred ictiv e o f success in school, h aving an average valid ity co e ffic ie n t (c o rre la tio n co e ffic ie n t c o rre c te d fo r u n r e ­ liability) o f betw een 0.50 an d 0.6 0 w ith la ter m easu res o f ac ad e m ic success like grades a n d ach ie v em e n t test scores.39 T h e value o f th is coefficient d ecreases at higher levels o f schooling, so th a t IQ is a m u c h b e tte r p re d ic to r o f success in high school, fo r exam ple, th a n in college o r g rad u a te sch o o l.40 M uch o f th is decrease in co rre la tio n m ay be th e resu lt o f ran g e restric tio n effects; th e range o f IQ s a m o n g tho se still in school decreases w ith years o f schooling, th u s reducing c o rre la tio n coefficients. IQ co rrela te s a b o u t 0 .60 w ith highest grad e o f school c o m p le te d .41

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C h risto p h e r Je n ck s an d his colleagues have review ed ev id en ce lin k in g IQ to o cc u p atio n al status, as m easu red by the ed u c atio n al re q u ire m e n ts a n d sa lary levels o f v a rio u s o c c u p a tio n s, a m o n g w h ite n o n fa rm A m eric an m ales. T h e c o rre la tio n betw een ad o lescen t IQ a n d ad u lt o c c u p atio n al sta­ tu s is q u ite high, averaging betw een 0.50 an d 0 .6 0 .42 It has been argued, however, th a t IQ has its effects on o cc u p atio n al statu s indirectly, via ed u c a ­ tio n a l a tta in m e n t;43 th a t is, tho se w ith higher IQs get b e tte r jo b s p rim arily b ecause these jo b s req u ire ap p lic a n ts to have c o m p leted m o re years o f schooling. In c o n tra st, m o st o f the c o rre la tio n betw een IQ an d in co m e, w hich is slightly g rea ter th a n 0.30, is in d e p e n d e n t o f th e effects o f a m o u n t o f schooling c o m p le te d .44 Finally, a rec en t review o f p red ictiv e validity o f v ario u s m easu res o f jo b p e rfo rm a n c e by Jo h n an d R o n d a H u n te r rep o rts th a t th e c o rre la tio n betw een tests o f general cognitive ab ility a n d jo b c o m ­ p eten ce varies w ith jo b re q u ire m e n ts, b u t is in all cases su b sta n tia l (greater th a n 0.30). T h e m e a n pred ictiv e validity (co rre latio n betw een test scores a n d jo b co m p ete n ce ) across all jo b categories stu d ied is betw een 0.50 an d 0 .6 0 , w ith validity bein g slightly higher for ease o f jo b tra in in g th a n fo r jo b p roficiency as m e asu red by supervisors’ ratings.45 In lin e w ith o u r ea rlier d iscussion, we m ay say th a t intelligence, as m e a ­ su red by intelligence tests, consists o f som e set o f skills th a t are very im p o r­ ta n t for success in school an d m o d erately im p o rta n t for success in th e jo b m a rk e t. T h is assum es, o f course, th a t intelligence tests are m e asu rin g skills, a n d n o t m erely class o r racial variables, i.e., th a t th e tests are n o t biased. T h e su b stan tia l c o rre la tio n s betw een ch ild h o o d IQ a n d ev en tu al o c c u p a ­ tio n a l sta tu s a n d in c o m e m ight lead o n e to co n c lu d e th a t w h atev er in te l­ ligence tests are m e asu rin g , it is im p o r ta n t for success in o u r society. C o rre la tio n is n o t necessarily ca u sa tio n , however, an d th e social m o b ility h y p o th esis (the idea th a t success is largely d e te rm in e d by o n e ’s abilities, in c lu d in g intelligence as m easu red by IQ tests) has been ch allen g ed o n th e g ro u n d th a t th e co rre la tio n betw een IQ a n d vario u s m easu res o f success is sp u rious. T h o se w ho disagree w ith the social m o b ility hy p o th esis generally c o n ­ cede th a t intelligence tests are good p red ic to rs o f success in school. T h ey arg u e th a t th is in d icates only th a t these tests m easu re a very n arro w c o n ­ ce p tio n o f intelligence, su b stan tia lly related to th e so rts o f verbal skills v alu able in school. In th e real w orld, it is said, th e im p o rta n c e o f these skills is d w arfed by such a ttrib u te s as persistence, a n d th e ab ility to get alo n g w ith o th e r people. T h is arg u m e n t has often been m a d e in resp o n se to H e rrn s te in ’s co n c lu sio n th a t SES is p a rtly heritable. T h e social m o b ility h y p o th ­ esis fo rm s an essential p a rt o f H e rrn s te in ’s syllogism (see C h a p te r 4). C h risto p h e r Je n ck s has also argued th a t in a d d itio n to in te rm e d ia ry elfects o f ed u c atio n al a tta in m e n t o n th e IQ -o c c u p a tio n a l statu s c o rre la ­ tio n . m u c h o f th is c o rre la tio n can be ex p lain ed by th e effects o f p are n ts’

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so c io eco n o m ic sta tu s (SES). C h ild re n ’s IQs co rrela te a b o u t 0 .30 w ith p a r­ e n ts’ SES, as m easu red by a n u m b e r o f variables, in c lu d in g q u ality o f h o m e e n v iro n m e n t, incom e, a n d o cc u p atio n al sta tu s.46 T h e c o rre la tio n betw een fathers’ an d sons’ o cc u p atio n al statu s is betw een 0 .40 a n d 0 .5 0 .47 It is th u s possible th a t m u ch o f th e c o rre la tio n betw een IQ an d ev en tu al o c c u p a ­ tio n a l statu s an d in c o m e is m erely a b y p ro d u c t o f in h e rited w ealth. (We will re tu rn in C h a p te r 4 to th e q u e stio n o f w hy th o se w ith higher SES have higher IQs.) In fact, Je n ck s et al. in th e ir analysis o f th e d e te rm in a n ts o f success in A m erica reveal th a t th e v aria tio n (stan d a rd d ev iatio n ) in o c­ cu p a tio n a l sta tu s am o n g m en w ith iden tical test scores is a b o u t 88 p erc en t o f th e v aria tio n a m o n g all m en. “T h is suggests th a t th e U n ite d States c a n n o t be co n sid ered a ‘m erito cracy ,’ at least if ‘m e rit’ is m e asu red by g eneral cognitive skills.”48 Je n ck s also cites d a ta in d ic a tin g th a t th e in te r­ g en e ratio n a l tran sm issio n o f SES is little affected by IQ .49 Such evidence n o tw ith stan d in g , th e co rre la tio n b etw een SES a n d IQ m ight involve causal effects ru n n in g in b o th d irectio n s. J u s t as th e q u ality o f e n v iro n m e n t prov id ed by p a re n ta l SES will in flu en ce IQ , so m ig h t o n e ’s intelligence (as m e asu red by th e tests) d e te rm in e o n e ’s ow n SES; social m o b ility m ay be in p a rt a fu n c tio n o f intelligence. E v id en ce for th is su p ­ p o sitio n can be fo u n d in th e fact th a t th e c o rre la tio n betw een ad o lesc en t IQ a n d la ter in c o m e increases w ith age. M oreover, Je ro m e W aller, in a 1971 stu d y o f 131 fathers a n d 170 o f th e ir sons, fo u n d a c o rre la tio n o f a b o u t 0.29 betw een fa th e r-so n IQ differences an d fa th e r-s o n SES differences; sons w ith higher IQ s th a n th e ir fathers w ere m o re likely to have h ig h er SES, w hile sons w ith low er IQs generally m oved dow n th e so c io eco n o m ic lad ­ der.50 7. In y o u r opinion, to what degree is th e average A m e r ic a n ’s socio­ econom ic sta tu s (S E S ) d e te rm in e d b y h is or her IQ ? T h e m a jo rity o f re sp o n d e n ts s u p p o rt th e idea th a t th e U n ite d S tates is so m ew h at o f an intellectu al m eritocracy. Sixty p erc en t feel th a t IQ is an im p o rta n t, b u t n o t th e m o st im p o rta n t, d e te rm in a n t o f SES. T w en ty -o n e p erc en t believe IQ plays on ly a sm all role in d e te rm in in g SES, a n d 3 p e rc e n t feel it is n o t at all im p o rta n t. O nly 2 p e rc e n t rate IQ as th e m o st im p o rta n t d e te rm in a n t o f SES. T h ere w ere 14 p e rc e n t n o n re sp o n d e n ts. “ T h e c o n s tru c t validity o f a test is th e e x te n t to w hich th e test m ay be said to m easu re a th e o re tic al c o n stru c t o r tra it.”51 Block a n d D w o rk in ’s criticism o f o p era tio n alism in intelligence testin g is based o n th is co n cep t. W ith o u t an idea o f w h at intelligence is, th e re is n o way o f k n ow ing if an in telligence test is w h at it claim s to be. T h ere are, o f co u rse, m a n y th e o ries o f intelligence, an d tests have been designed w ith th e c o n stru c ts o f these

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th eo ries in m in d , b u t th e re still is n o generally accep ted th e o re tic al a c c o u n t o f intelligence. O u r ea rlier q u estio n a b o u t im p o rta n t elem e n ts o f in tellig en ce n o t ad e­ q u ately m e asu red by intelligence tests is in fact a cru d e m easu re o f o p in io n a b o u t c o n stru c t validity; we a tte m p te d to assess th e degree to w hich ex p erts believe these tests m easu re c e rta in th e o re tic al co n stru c ts, such as “ th e cap acity to acq u ire know ledge.” A m o re c o m m o n source o f c o n stru c t val­ id a tio n for intelligence tests is c o rre la tio n w ith existin g tests; if scores on tw o tests are highly c o rrela te d , th e n th e tests are assu m ed to be m easu rin g th e sam e co n stru c ts. T h e success o f th is strategy is lim ited by th e co n s tru c t v alidity o f existing tests. U n fo rtu n a tely , m a n y o f these tests have n ot th e m ­ selves been subject to c o n s tru c t v alid atio n . For ex am p le, th e S tan fo rd rev i­ sio n s o f the B in e t-S im o n scales have been a m o n g th e m o st w idely used o f such sta n d ard s. T h e B in e t-S im o n test m ay have h ad som e c o n s tru c t v alid ­ ity, as T erm an a n d o th e rs n o te d in ex p lain in g its success, b u t th ese w ere p o s t-h o c analyses. T h e te st w as ad o p te d because o f its c rite rio n validity. C o rre la tio n w ith ex isting tests is d o n e as a fo rm o f c o n s tru c t v alid atio n ; if scores o n tw o tests are highly c o rrela te d , th e n th e tests are assu m ed to be m e asu rin g th e sam e co n stru c ts. T h e success o f th is strategy is lim ited by th e c o n stru c t validity o f existing tests. M uch c o n stru c t v alid atio n o f intelligence tests, an d , in fact, m u c h in te l­ ligence theory, c o m es from a n o th e r so u rce, sta tistic a l an aly ses o f te st scores. T h e in te rp re ta tio n o f these analyses has been o n e o f th e m o st ho tly d eb ated top ics in th e intelligence literatu re . A t th e ce n te r o f th is d eb a te are arg u m e n ts o ver th e existence an d sta tu s o f a general m e n ta l ability. P sy ch o ­ m e tricia n s disagree a b o u t th e e x te n t to w hich scores on in telligence an d g eneral a p titu d e tests reflect p rim a rily a single a p titu d e , o r a larger n u m b e r o f in d e p e n d e n t cog nitive abilities. T hose w ho argue for th e existence o f a general m e n tal ab ility rely heavily on the fact th a t v irtu ally all tests o f intelligence an d m e n tal a p titu d e are positively c o rre la te d .52 T h is p h e n o m e n o n w as first n o te d in 1904, th e year before th e p u b lic a tio n o f th e B in e t-S im o n scale, by E nglish psychologist C h arles S p e a rm a n .53 S p e a rm a n , a disciple o f G a lto n ’s, h ad been using th e new ly in v e n ted c o rre la tio n a l te c h n iq u e s to investig ate th e rela tio n sh ip b e­ tw een vario u s m easu res o f intelligence: te ac h er a n d p eer ratings, school grades, a n d sensory an d m e m o ry test scores. U n lik e C lark W issler, S pear­ m a n was im p ressed by th e su b stan tia l in te rc o rre la tio n betw een th e v ario u s m easu res (S p e arm an n o te d th a t W issler’s c o rre la tio n s w ere to o low becau se he h ad failed to co rrec t for th e u n reliab ility o f his m easures), a n d p a r­ tic u la rly by th e very high p o sitiv e c o rre la tio n s b etw een g rad es o f p re ­ p a ra to ry school stu d e n ts in each o f six subjects, ran g in g fro m E nglish an d m a th e m a tic s to m usic. S tu d en ts w ho d id well in o n e su b ject w ere likely to

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d o well in all o f th e m . S p e a rm a n hyp o th esized th a t th is p a tte rn co u ld be ex p la in e d by a single u n d e rly in g factor, w hich h e called g en eral in te l­ ligence, o r g. W ith the ad v e n t o f th e first w orkable intellig en ce tests, S p e a rm a n was prov id ed w ith an even g rea ter d a ta base, a n d his w ork o n th e stru c tu re o f intelligence c o n tin u e d apace. In o rd e r to m o re precisely define th e m a n n e r in w hich a p a tte rn o f c o rre la tio n s betw een tests reflected c o m m o n u n d erly ­ ing en titie s like g, S p earm a n in v e n ted a te c h n iq u e k n o w n as facto r an a ly ­ sis, w h ic h h a s b e c o m e th e p r im a ry to o l o f c o n s tr u c t v a lid a tio n in p sych o m etrics. F acto r analysis is a m e th o d by w hich th e set o f c o rre la tio n s betw een a large n u m b e r o f en titie s (in th is case scores o n d ifferen t tests o r subtests) m ay be redescrib ed in te rm s o f a sm aller n u m b e r o f factors. T h e an alysis p ro d u ce s a set o f fac to r “ loadings” fo r each e n tity th a t reflect th e d egree to w hich th e en tity in q u e stio n m e asu res each factor. T h u s, for ex am p le, a set o f c o rre la tio n s betw een tw en ty a p titu d e tests m ay be d e­ scribed by fo u r u n d erly in g factors. E ach test m e asu res th e fo u r facto rs to varying degrees, as in d ic ated by th e ir fa c to r loadings. S p e a rm a n fo u n d , as he h ad p red icted , th a t m o st c o rre la tio n s betw een test scores he an aly zed co u ld be d escribed in te rm s o f o n e u n d erly in g facto r o n w hich all o f th e tests h ad fairly high loadings, i.e. g. Tests th a t h a d a large n u m b e r o f high c o rre la tio n s w ith o th e r tests w ere said to be m o re “g lo a d e d ” th a n tho se w ith a p re p o n d e ra n c e o f low er co rrela tio n s. F ro m th e results o f m a n y such facto r analyses S p e a rm a n d ev elo p ed his tw o -fa c to r th e o ry o f in tellig en ce.54 A ny given cognitive ac tiv ity (o r p e rfo rm a n c e on an y test o f m e n tal ability) co u ld be a c c o u n te d for by g, th e g en eral in te l­ ligence fac to r c o m m o n to all such activities (o r tests), a n d by a special (o r g ro u p ) factor, s, reflecting abilities u n iq u e to th a t activ ity (o r test). S p e a rm a n s th e o ry w as a d o p te d by m a n y o f th e early m e n ta l testers as an e x p la n a tio n o f th e ir test results; as a m easu re o f g, in tellig en ce test scores to o k on even g rea ter significance. O n ce tests w ere firm ly estab lish ed , th e statistical analysis o f intelligence tests scores b ecam e o n e o f th e p rim a ry m e an s by w hich th e o ries o f intelligence w ere d ev elo p ed a n d v alidated. T h re e im p o rta n t p o in ts a b o u t fac to r analysis sh o u ld be n o ted . First, fac to r analysis is a purely statistical te c h n iq u e th a t d o es n o th in g m o re th a n redescribe a set o f co rrela tio n s. F actors are descrip tiv e categories, or, a t b est, h y p o th e tic al co n stru c ts, a n d sh o u ld n o t be th o u g h t o f as a c tu a l u n d e r­ lying entities. Second, fac to r analysis p ro d u c e s a set o f facto rs th a t re­ d escribe th e d a ta — it does n o t in te rp re t th ese factors. In te rp re ta tio n is left to th o se w ho ex a m in e th e results o f th e analysis, a n d is u su ally a c c o m ­ p lished by n o tin g th e sim ilarities betw een th o se en titie s th a t lo ad highly on a given factor. Finally, th e re are an infinite n u m b e r o f fac to r an a ly tic so lu ­ tio n s for an y set o f c o rre la tio n s (w hich is n o t to say th a t th ese so lu tio n s are

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n o t u n iq u e to th e set o f c o rrela tio n s being analyzed). T h e so lu tio n a rriv ed at d ep e n d s on th e value o f c e rta in p a ra m e te rs specified by th e an aly st, w ho has c e rta in goals in m in d . S p e a rm a n p erfo rm ed his analyses so th a t each te st w ould have th e highest possible loading on o n e factor. It sh o u ld be u n d ersto o d , however, th a t S p e a rm a n ’s analyses w ould n o t have p ro d u ce d th e results they d id if th e original set o f c o rre la tio n s h ad n o t allow ed it. If few o f th e tests co rrela te d positively, o r if th e re w ere m a n y negative c o rre la ­ tio n s, th e analyses w ould n o t have been able to p ro d u ce o n e facto r on w hich m o st tests lo ad ed highly. N evertheless, th e p receding caveats m ak e it clear th a t o n e m ay arriv e a t a large an d varied n u m b e r o f reaso n ab le so lu tio n s a n d in te rp re ta tio n s from th e sam e set o f test score co rrela tio n s. F a c to r-a n a ly sis th e o rists te n d to fall in o n e o f tw o cam ps; tho se w ho h y pothesize a p rim a ry general intelligence facto r a n d su b sid iary factors o f special abilities, an d th o se w h o see in te l­ ligence as co m p o sed en tirely o f sep arate faculties. L. L. T h u rs to n e w as th e first to p o in t o u t th a t th e sam e set o f test scores co u ld be facto r an aly zed to p ro d u ce , in stead o f o n e general factor, a sm all n u m b e r o f factors. T h u rs to n e called these factors p rim a ry m e n tal abilities, each o f w hich has a b o u t equal facto r loadings across all tests. H e also n o ted th a t th e in te rp re ta tio n given to g d ep e n d s largely o n th e p a rtic u la r tests w hose scores are fac to r analyzed. In 1935, T h u rs to n e p u b lish ed T h e Vec­ tors o f M in d , in w hich he h ypothesized th a t intellig en ce m ig h t co n sist o f a relatively sm all n u m b e r o f in d e p e n d e n t faculties c o rre sp o n d in g to different co g nitive d o m a in s, each o f w hich c o n trib u te s to a g reater o r lesser degree to in tellectu al fu n ctio n in g in any p a rtic u la r situ atio n . Based on his ow n re­ search a n d test d ev e lo p m e n t, T h u rs to n e w as able to id en tify eight p rim a ry m e n tal abilities: verbal ability, in d u c tiv e o r general reaso n in g , n u m erical ability, ro te m em ory, p ercep tu al speed, w ord fluency, sp atial ability, an d d ed u c tiv e reasoning. All b u t th e last o f th ese have been fre q u en tly c o rro b o ­ rated by th e w ork o f o th e r m u lti-fa c to r th e o rists.55 It is in terestin g th a t, d esp ite his b elief th a t intelligence sho u ld n o t be d escrib ed in te rm s o f a general factor, T h u rs to n e later observed th a t his sm all n u m b e r o f p rim a ry factors w ere them selv es in te rc o rre la te d , leading h im to p o stu late a "sec­ o n d - o rd e r g.” 56 P erhaps th e m o st ex trem e fo rm o f th e m u lti-fa c to r view is rep resen ted by th e stru c tu re -o f-in te lle c t m odel o f J. P. G u ilfo rd .57 G u ilfo rd has p o s tu ­ lated som e 120 in te lle ctu al factors based on a th e o re tic al sch em e in w hich an intellectu al activity m ay be described in te rm s o f o n e o f five ty p es o f m e n tal o p e ra tio n , four types o f c o n te n t, a n d six types o f p ro d u ct. T h e m o del d oes n o t deal w ith an y general abilities. G u ilfo rd a n d his associates have developed tests th a t a tte m p t to iden tify th e facto rs h y p o th esized by th e m odel. A fter tw enty years o f research a n d test d ev e lo p m e n t, n in e ty -

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eight factors h ad been id e n tified .58 T h a t m o st o f th ese facto rs are c o rrela te d has been a m a jo r criticism o f G u ilfo rd ’s a n ti- g p o sitio n .59 N o n eth eless, G u ilfo rd ’s w ork is a good ex am p le o f how intellig en ce th e o ry a n d m e asu re­ m e n t m ay progress together. G en eral intelligence th e o rists d o n o t d isregard th e idea o f se p arate m e n ­ tal abilities, b u t argue th a t tests o f these abilities are so highly c o rrela te d th a t th e re m u st be so m e m o re general fac to r in flu en cin g p e rfo rm a n c e on all o f th em . H ierarch ical o rg an iz atio n is c o m m o n to m a n y th eo ries p o s­ tu la tin g a general intelligence factor.60 P h ilip V ern o n , fo r ex am p le, places g a t th e to p o f th e hierarchy. T h e “ m a jo r g ro u p facto rs,” v e rb a l-e d u c a tio n a l an d sp a tia l-m e c h a n ic a l, c o n stitu te th e second echelon. U n d e r th ese are ce rta in m in o r g ro u p fac to rs,” an d finally specific facto rs u n iq u e to each test. T he m o re an y given test ta p s in to abilities in th e u p p e r levels o f th e hierarchy, th e m o re scores from th e test will c o rre la te w ith th o se fro m o th e r in telligence a n d a p titu d e tests. Jo h n C a rro ll has n o te d th a t, because o f th e so m ew h at a rb itra ry n a tu re o f fa c to r-a n a ly tic so lu tio n s, th e m o d els o f Ver­ n o n a n d T h u rs to n e are in te rc o n v e rtib le .61 A n o th e r p o p u la r an a ly tic so lu tio n is R a y m o n d C a tte ll’s d istin c tio n b e­ tw een fluid a n d crystallized general intelligence.62 F lu id g involves n o n v er­ bal, c u ltu re -fre e skills th o u g h t to be g reatly d e p e n d e n t on physiological stru ctu re s. C rystallized g refers to ac q u ired skills an d know ledge th a t d e ­ p en d on ed u c atio n al an d c u ltu ra l factors, a n d on fluid intelligence. F lu id in telligence increases u n til adolescence, afte r w hich it declines, as p h y s­ io lo g ic a l s tr u c t u r e s d e t e r io r a te . C r y s ta lliz e d in te llig e n c e in c re a s e s th ro u g h o u t life u n til severe d e te rio ra tio n o f physiological stru c tu re s (fluid intelligence) late in life causes ac q u ired know ledge to d ecrease as well. IQ tests like th e S ta n fo rd -B in e t an d th e W echsler tests m e asu re b o th fluid a n d crystallized intelligence. A ch ie v em en t tests are b e tte r m easu res o f cry s­ tallized th a n fluid intelligence, w hile C attell has dev elo p ed n o n v erb a l tests th a t are alm o st en tirely m e asu res o f fluid intelligence. If we are to believe general intelligence th eorists, g is th e m o st im p o rta n t asp ect o f intelligence. B ut w h at is g? As a m a tte r o f fact, g is a label given to p a rt o f th e o u tp u t o f a statistical analysis describ in g a high degree o f in te r­ co rrela tio n betw een tests o f m e n tal ability. A n y th in g else th a t m ay be said a b o u t g is an in te rp re ta tio n based o n an ex a m in a tio n o f th o se tests th a t load highly on th e “general in tellig en ce” factor. We m ay h yp o th esize th a t tests th a t load highly on g are m e asu rin g so m e u n d erly in g g eneral ability, b u t we on ly kn o w th a t such tests co rrela te highly w ith m a n y o th e r tests. Je n sen has looked closely a t tho se tests th a t load highly on g. T hese in c lu d e tests o f verbal sim ilarities an d differences, verbal analogies, series c o m p letio n , figure analogies, an d a rith m e tic reasoning. Tests th a t load p o o rly o n g in c lu d e speed o f sim ple a d d itio n , ro te m e m o ry tasks, a n d

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sim p le reactio n tim e. Je n sen reaches tw o co n c lu sio n s from his e x a m in a ­ tion: first, "g is not related to th e specific c o n te n ts o f item s o r to th e ir surface ch aracteristics.”63 In o th e r w ords, w hatev er is cau sin g tests to c o rre ­ late highly is a g eneral characteristic. S econd, “g seem s to be involved in item s th a t req u ire m en tal m a n ip u la tio n o f im ages, sym bols, w ords, n u m ­ bers. o r concepts. Tests th a t m erely call for recall o r re p ro d u c tio n o f p re ­ vio u s le a rn in g o r highly p rac tice d skills are p o o r m e asu res o f g.”64 In a d d itio n , Jen sen n otes th a t th e higher a test loads on g, th e b etter it c o rre ­ lates w ith subjective im pressions o f intelligence. For these reasons, Jen sen a n d o th e rs have h ypothesized th a t tests o f m e n tal ab ility th a t co rrela te well w ith m a n y o th e r tests do so because they req u ire a great deal o f general in tellectu al ability. M u lti-fa c to r th e o rists argue th a t th e c o rre la tio n betw een tests o f d if­ feren t a p titu d e s is th e result o f an in d e p e n d e n t, b u t co ex isten t, set o f ab il­ ities. T hey p o in t o u t th a t it is possible to c o n s tru c t tests th a t m easu re these specific abilities, a n d th a t th e co rrela tio n betw een th ese tests is far from perfect. T h e existence o f id io t savants (m en tal re ta rd a te s possessing e x tra ­ o rd in a ry abilities in o n e specific area), an d , m o re generally, th e u n iq u e profile o f intellectu al abilities displayed by all persons, arg u e for th e exis­ ten ce o f in d e p e n d e n t a ttrib u te s .65 8. Is intelligence, as m ea su red b y intelligence tests, b etter d escribed in te rm s o f a p rim a ry g eneral intelligence fa c to r a n d su b sid ia ry group o f special a b ility fa ctors, or entirely in te rm s o f separate fa c u ltie s? D espite the " a rb itra rin e ss” o f facto r an aly tic solutio n s, m o st resp o n d e n ts hold definite o p in io n s o n how to m o st m ean in g fu lly to describe in te l­ ligence test results. F ifty -e ig h t p erc en t favor som e fo rm o f a general in te l­ ligence so lu tio n , w hile 13 p erc en t feel se p arate faculties are a su p e rio r d escrip tio n . O nly 16 p erc en t th in k th e d a ta are sufficiently am b ig u o u s as n o t to favor e ith e r so lu tio n . N o n re sp o n se rate w as 13 p ercen t. O p in io n s a b o u t g tell us w h at m o st ex p erts believe a b o u t th e stru c tu re o f intelligence, at least as m easu red by intelligence tests. T h e re is also a m o re practical co n seq u en ce. T h e revised ed itio n o f th e W echsler In telligence Scale for C h ild re n (W IS C -R ) an d th e S ta n fo rd -B in e t are th e tw o m o st w idely used in d iv id u a lly -a d m in is te re d intelligence tests. T h e ir m o st im ­ p o rta n t use is in ed u c a tio n p la n n in g for sp e c ia l-n e e d s stu d en ts. Because th ese tests yield se p arate subscores for such skills as verbal a n d arith m e tic reasoning, tra in e d test a d m in istra to rs can diagnose specific deficits an d help plan a p p ro p ria te re m e d ia tio n program s. T hese tests also yield an o m n ib u s IQ. T h a t th e subscales o f these tests are su b stan tia lly in te rc o rre ­ lated an d th a t th e tests are highly g -lo a d e d m ean s, a t least for believers in g.

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th a t th e sin g le-sco re IQ is also a highly m e an in g fu l m easu re, as are global scores on o th e r general a p titu d e batteries. Issues o f th e stru c tu re o f intelligence aside, ex a m in a tio n o f m o d e rn in telligence tests in d icates th a t these tests are m easu rin g so m e set o f in te l­ lectual skills. T h e W IS C -R , for exam ple, is extrem ely reliable, has good c o n c u rre n t a n d pred ictiv e validity, loads highly on g, a n d has been well sta n d a rd iz e d for A m erican c h ild re n .66 T h e W IS C -R co n sists o f th e follow ­ ing subtests: general in fo rm a tio n , w ord sim ilarities, a rith m etic, v o ca b u l­ ary, p ro b lem co m p re h e n sio n , digit span, p ic tu re c o m p letio n , block design, o b ject assem bly, coding, an d m azes. It w ould be difficult to arg u e th a t W IS C -R scores do not reflect in tellectu al abilities. Two fu rth e r q u e stio n s a b o u t intelligence tests seem relev an t. F irst, to w h at ex ten t d o th ese tests m e asu re o th e r th a n in te lle ctu al factors? Second, w h at im p o rta n t factors are n o t m e asu red by intellig en ce tests? In a sense, th ese q u e stio n s are ju s t a n o th e r way o f asking how in telligence test scores are related to “ intelligence,” b u t in a fo rm th a t m ay be m o re answ erable. Tests th a t m easu re to an y significant e x te n t n o n in te lle c tu a l facto rs asso­ c iated w ith SES, class, o r c u ltu re are biased. T h e n a tu re a n d e x te n t o f bias in intelligence tests will be discussed in C h a p te r 4. F or now we m ay ask w h eth e r intelligence tests m easu re any personality, m o tiv a tio n a l, o r e m o ­ tio n a l factors n o t generally th o u g h t to be p a rt o f intelligence. T h e an sw er d ep en d s, o f course, o n o n e ’s d efin itio n o f intelligence, b u t few w ould arg u e th a t intelligence tests sh o u ld be m easu rin g such th in g s as w illingness to co m p ly w ith in stru c tio n s o r e m o tio n a l lability (th o u g h th ese a ttrib u te s m ight be q u ite pred ictiv e o f ac ad e m ic success). T h a t in telligence tests are in fluenced by such factors is generally agreed u p o n by th o se w h o stu d y te stin g .67 T h e degree o f th is influence is u n c e rta in . T h e ev id en ce is q u ite clear, however, th a t th e perso n al ch a racteristics o f th e exam iner, th e ra p ­ p o rt established betw een th e e x a m in e r an d th e su b ject, th e su b je ct’s ph y s­ ical a n d e m o tio n a l state, a n d te st an x iety ca n all in flu en ce in tellig en ce test scores. F or th is reason, p sy c h o m etric tex ts a n d test m a n u a ls c o n ta in n u ­ m e ro u s w arn in g s a n d suggestions fo r cre atin g as “ o b jectiv e” a te stin g e n ­ v ir o n m e n t as p o ssib le, a n d fo r ta k in g e x tr a - in te lle c tu a l fa c to rs in to a c c o u n t w hen in te rp re tin g te st results. (It also ex p lain s w hy th o se w ho a d m in iste r intelligence a n d a p titu d e tests, p a rtic u la rly to in d iv id u als, m u st be well tra in e d .) W hile it m ay be im p o ssib le to d e te rm in e th e p recise in fluence o f these factors in a n y given case, th o se w ho fail to heed th e w arn in g s will ce rtain ly o b ta in less co m p re h en sib le, a n d less accu rate, test scores. Block an d D w o rk in argue th a t intelligence tests also m easu re su ch per­ so n ality a n d m o tiv a tio n a l factors as persisten ce an d atten tiv en ess. T h ese tra its a re p resu m a b ly little influenced by an e x a m in e r’s a tte m p ts to m ak e

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th e te stin g situ a tio n m o re a m e n a b le to m ean in g fu l m e asu rem en t. T h e im p o rta n c e o f p ersistence an d atten tiv en e ss violates th e n o tio n o f “ in te l­ ligence” testing, ac co rd in g to Block an d D w orkin, becau se such traits are c le a rly n o n in te lle c tu a l. B ut th e s e a u th o r s also in d ic a te th a t D a v id W echsler, dev elo p er o f th e W1SC an d WAIS, believed th a t a ttrib u te s like p ersisten ce a n d atten tiv en e ss are p a r t o f general intelligence, d efining in te l­ ligence as a d a p tiv e behavior. T h u s we re tu rn to th e p ro b lem en c o u n te re d in th e 1921 a n d 1986 sy m p o sia o f how bro ad ly such a d a p tiv e b eh av io r is to be defined. 9. T h e im p o rta n ce o f p erso n a l characteristics to intelligence test perform ance. R e sp o n d e n ts w ere asked to rate each o f six perso n al ch aracteristics for th e ir im p o r ta n c e to p e r f o rm a n c e o n in te llig e n c e te sts. T h ese c h a r a c ­ teristics are a c h ie v em e n t m o tiv a tio n , anxiety, atten tiv en e ss, e m o tio n a l la ­ bility, persistence, an d physical h ealth . R atin g s w ere m a d e o n a 4 - p o in t scale, w here 1 w as “ O f little im p o rta n c e ,” 2 w as “ S o m ew h at im p o r ta n t,” 3 was “ M o d erately im p o r ta n t,” a n d 4 was “ Very im p o rta n t.” T h e results o f q u e stio n 8 are show n in Table 2.5. All ch aracteristics are seen as a t least so m e w h at im p o rta n t to test p e rfo rm a n c e , th o u g h o nly atten tiv en e ss is m o re th a n m o d erately im p o rta n t. N o n eth eless, ex p e rt re­ sp o n d e n ts believe th a t intelligence test scores can be su b stan tia lly affected by tra its tra d itio n a lly co n sid ered n o n in te lle ctu al. T h e case is m o st clearly

TABLE 2.5 Importance of Personal Characteristics to Intelligence Test Performance Characteristic Achievement motivation Anxiety Attentivenesss Emotional lability Persistence Physical health

Mean Importance Rating* 2.87 (.964)» 2.68 (.901) 3.39 (.744) 2.52 (.938) 2.96 (.872) 2.34 (.892)

*1 = "Of little importance,” 2 = "Somewhat important,” 3 = "Moderately important,” and 4 = "Very important."’ b. Numbers in parentheses are standard deviations.

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m a d e for a c h ie v em e n t m o tiv atio n . W hile on ly 19 p e rc e n t o f re sp o n d e n ts b elieve ach ie v em e n t m o tiv a tio n is an im p o rta n t e le m e n t o f in tellig en ce (Table 2.3), th is tra it receives a m ean ratin g o f 2.87 o n th e 4 - p o in t scale o f im p o rta n c e to te st p erfo rm an ce . “ A psychological test is essentially an objectiv e a n d sta n d a rd iz e d m e a ­ sure o f a sam p le o f behavior.”68 A n intelligence test is a m easu re o f a sam p le o f in te llig e n t b eh av io r. T h e re p re s e n ta tiv e n e s s o f th a t sa m p le is th e p ro v in ce o f te st v alid atio n , w ith all its a tte n d a n t am b ig u ities. In th is so­ ciety, intelligence tests sam p le b eh av io r th a t is p red ictiv e o f (a n d p re su m ­ ably im p o rta n t to) success in o u r school system s a n d in th e jo b m a rk e t. O th e r skills a n d a ttrib u te s, w hich m ay be eq u ally im p o rta n t to success, are little m easu red . (See Je n ck s et al. ’s 1972 b o o k In e q u a lity fo r an ex cellen t d iscussion o f th e im p o rta n c e o f n o n co g n itiv e tra its to success.) T h e ir ex­ clu sio n m ay be d u e to th e failure o f te stm a k e rs to p ro d u c e an a d e q u a te sam ple, b u t m o re likely is a reflection o f th e lim its o f even so n e b u lo u s a c o n c e p t as intelligence. Sociability, physical attractiv en ess, a rtistic ta len t, m o to r co o rd in a tio n , creativity, a n d th e n eed for pow er u n d o u b te d ly all c o n trib u te to o n e ’s success in W estern society, yet n o n e o f th ese a ttrib u te s are m e asu red by intelligence tests to an y significant degree. N o r w ould m an y people argue th a t th ey sh o u ld be. O th e r abilities, like co m p lex p ro b ­ lem solving a n d m a th e m a tic a l reasoning, are n o t sa m p le d by m a n y in te l­ ligence tests, yet are generally th o u g h t to be p a rt o f in tellig en t behavior. T h e restric tio n s placed o n th e b ehaviors sam p led by in tellig en ce tests re p ­ resen t a b a lan c e betw een efficiency, g rea ter pred ictiv e validity, a n d th e lim ita tio n s o f even th e m o st broadly defined n o tio n o f intelligence. Summary In general, ex p e rt o p in io n o n th e n a tu re o f in tellig en ce ru n s c o n tra ry to th e m o st c o m m o n criticism s o f testing. M ost ex p e rts believe th a t p sy ch o ­ logists an d ed u c ato rs are in general ag re em e n t a b o u t th e d efin itio n o f intelligence. T h is a g re em e n t is d e m o n stra te d em p irically for th e basic ele­ m e n ts o f ab stra c t reasoning, p ro b le m -so lv in g ability, a n d th e cap acity to a c q u ire know ledge. C o n sid erab le d isa g re em en t still re m a in s a b o u t th e v ari­ ety o f behaviors to in c lu d e in a d efin itio n o f intelligence. T h is d isco rd a b o u t th e precise stru c tu re o f intelligence is reflected in th e m ajo rity o p in ­ io n th a t th e d e v e lo p m e n t o f intelligence tests has n o t b ee n g u id ed by a unified th e o ry o f intelligence, th o u g h it is u n clea r how a lack o f th e o ry relates to th e validity o f th e tests. R e sp o n d en ts also feel th a t in tellig en ce tests are d o in g an a d e q u a te jo b o f m easu rin g th e im p o r ta n t elem e n ts o f intelligence, b u t th a t c e rta in n o n in te lle ctu al perso n al c h a ra c te ristic s can have a significant effect on intelligence te st p e rfo rm a n c e . E x p erts disagree

The Nature of Intelligence

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th a t intelligence tests are n o th in g b u t m easu res o f ac q u ired know ledge, b u t d o in d ic ate th a t w h atev er th e tests are m easu rin g it is n o t as stable as a pu rely physical ch a racteristic such as height. W h atev er intelligence tests are m easuring, th e m a jo rity o f ex p erts believe it is an im p o rta n t d e te rm i­ n a n t o f success in A m erican society. Finally, ex p e rts believe intelligence, as m e asu red by tests, to be best d escribed in te rm s o f general in telligence an d su b sid iary factors. In response to th e general q u estio n o f th e n a tu re o f intelligence, m o st p sy c h o m etric ia n s m a in ta in som e fo rm o f o p era tio n alism , b eing m o re c o n ­ ce rn ed w ith valid atin g tests th a n w ith th e o rizin g a b o u t co g nitive abilities. C o g nitive scientists, on th e o th e r h an d , rarely are co n c e rn e d w ith “ in te l­ lig en ce” an d even m o re rarely a tte m p t to q u a n tify in d iv id u al differences in co g n itive abilities for use as d e c isio n -m a k in g tools. T h is tra d itio n a l rift b etw een m e a su re m e n t an d th e o ry ac c o u n ts for m u c h o f th e am b ig u ity c o n c e rn in g d efin itio n s o f intelligence. B ut th e re is m o re to th e p u b lic d e­ b ate over th e n a tu re o f intelligence th a n th e p a rtic u la r co g n itiv e tra its to be in clu d ed in so m e d efin itio n , o r how these tra its are related . B u rt’s d efin i­ tio n o f intelligence as “in n a te general cognitive ca p ac ity ” em p h asizes th e h eritab le n a tu re o f intelligence an d th e b elief th a t in tellig en ce is a largely fixed ch a racteristic o f th e in d iv id u al. C ritics fear th a t it is as m easu res o f fixed capacity th a t intelligence an d ap titu d e tests are in te n d e d an d in te r­ p reted. T h a t a tw o -h o u r p a p e r -a n d -p e n c il exam p u rp o rts to tell us so m e­ th in g a b o u t o u r inherent w o rth is o n e ro u s to m o st o f us. T h e sta tu s o f in telligence as an in n a te ch aracteristic is th e sub ject o f th e n ex t chapter. N otes 1. E. L. Thorndike et al., “Intelligence and Its Measurement: A Symposium,” Journal o f Educational Psychology 12 (1921): 124—147, 195-216, 271-275. 2. Ibid.. p. 128. 3. Ibid., p. 137. 4. Frank N. Freeman. “A Referendum of Psychologists: A Survey of Opinion on the Mental Tests." Century M agazine 107 (1923):237—245. 5. Robert L. Sternberg et al. “People’s Conceptions of Intelligence,” Journal o f Personality and Social Psychology 41 (1981 ):37—55. 6. T. Anne Cleary et al. “Educational Uses of Tests with Disadvantaged Students,” American Psychologist 30 (1975): 19. 7. Robert J. Sternberg and Douglas K. Detterman, eds., What Is Intelligence? (Norwood, NJ: Ablex, 1986). 8. Robert J. Sternberg and Cynthia A. Berg, “Quantitative Integration: A Com­ parison of the 1921 and 1986 Symposia," in What Is Intelligence?eds. Robert J. Sternberg and Douglas K. Detterman (Norwood, NJ: Ablex, 1986), pp. 157— 158. 9. Other areas that have been or are being studied include nuclear energy, environ­ mental cancer, and gender differences. For discussions of the historical the­

76

10. 11. 12.

13. 14. 15. 16. 17. 18.

19. 20. 21. 22. 23.

24.

25. 26.

27. 28.

The IQ Controversy oretical issues as well as some of the case studies, see chs. ; S. Robert Lichter, Stanley Rothman and Linda Lichter The Media Elite (Washington, D.C.: Adler and Adler, 1986); Stanley Rothman, S. Robert Lichter, and Linda Lichter, Elites in Conflict: Social Change in America; Stanley Rothm an and S. Robert Lichter, “Elites in Conflict: Nuclear Energy, Ideology, and the perception of R isk,” Journal o f C ontem porary S tu d ie s 8,3 (S u m m er/F all, Transac­ tion/Society 23,3 (March/April, 1986), pp. 5-8. Cyril Burt, “ Mental Capacity and Its Critics,” Bulletin o f the British Psycholog­ ical Society 21 (1968): 11-18. A rthur R. Jensen, “How Much Can We Boost IQ and Scholastic Achieve­ ment?” Harvard Educational Review 39 ( 1969):5. Hans J. Eysenck, ed., A M odel fo r Intelligence (New York: Springer-Verlag, 1982); Howard Gardner, Frames o f Mind: The Theory o f M ultiple Intelligences (New York: Basic Books, 1983). N. J. Block and Gerald Dworkin, eds.. The IQ Controversy (New York: Pan­ theon Books, 1976), p. 28. Edwin G. Boring, “ Intelligence as the Tests Test It,” N ew Republic 35 (1923):35—37. cf. Eysenck; Robert L. Sternberg, ed., Recent Advances in Research on Intel­ ligence (Hillsdale. NJ: Lawrence Erlbaum, 1982). Cleary et al., p. 19. Robert J. Sternberg and Cynthia A. Berg, “Quantitative Integration: A Com ­ parison of the 1921 and 1986 Symposia,” in What Is Intelligence? eds. Robert J. Sternberg and Douglas K. D etterman (Norwood, NJ: Ablex, 1986), p. 157. N. J. Block and Gerald Dworkin, “IQ, Heritability and Inequality,” in The IQ Controversy eds. N. J. Block and Gerald Dworkin (New York: Pantheon Books, 1976), pp. 410-540. Block and Dworkin, p. 423. Lewis M. Term an, The M easurem ent o f Intelligence (Boston: H oughton Mifflin, 1916). Thorndike et al., p. 131. Ibid. Douglas K. Detterman, “Quantitative Integration: The Last Word?” in What Is Intelligence? eds. Robert J. Sternberg and Douglas K. Detterman (Norwood, NJ: Ablex, 1986), p. 164. For example, Raymond B. Cattell, “A Culture-Free Intelligence Test, Part I.” Journal o f Educational Psychology 31 (1940): 161-179; Raymond B. Cattell, “Theory of Fluid and Crystalized Intelligence: A Critical Experiment,” Journal o f Educational Psychology 54 (1963): 1-22; J. P. Guilford and R. Hoepfner, The Analysis o f Intelligence (New York: McGraw-Hill, 1971). Jerome M. Sattler, Assessment o f Children’s Intelligence and Special Abilities, 2nd ed. (Boston: Allyn and Bacon, 1982), p. 440. Cleary et al., p. 21; Robert A. Gordon, “Labelling Theory, M ental Retardation, and Public Policy: Larry P. and Other Developments Since 1974,” in The Labeling o f Deviance: Evaluating a Perspective, 2nd ed., ed. Walter R. Gove (Beverly Hills, CA: Sage Publications, 1980), pp. 190-191. David Owen, None o f the Above: Behind the M yth o f Scholastic Aptitude (Boston: Houghton Mifflin, 1985). Anne Anastasi, Psychological Testing, 5th ed. (New York: Collier Macmillan, 1982), p. 395.

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29. Gordon, p. 190. 30. Block and Dworkin, p. 445. 31. A rthur R. Jensen, Bias in M ental Testing (New York: Free Press, 1980), pp. 261-262. 32. Ibid., p. 270. 33. Sattler, p. 57. 34. Jensen, “How M uch,” p. 18; Sattler, p. 58. 35. Benjamin S. Bloom, Stability and Change in Human Characteristics (New York: Wiley, 1964), p. 61. 36. Jensen, “How M uch,” p. 19. 37. Anastasi, p. 131. 38. Ibid.. p. 137. 39. Jensen, Bias, pp. 317-319. 40. Ibid.. p. 319. 41. Christopher Jencks et al.. Inequality (New York: Basic Books, 1972), p. 144. 42. Ibid.. p. 185; Jensen, Bias, p. 341. 43. Otis Dudley D uncan, “Ability and Achievement,” Eugenics Quarterly 15 (1968): 1—11. 44. Christopher Jencks et al., Who Gets Ahead? (New York: Basic Books, 1979), p. 121.

45. John E. H unter and Ronda F. Hunter, “Validity and Utility of Alternative Predictors of Job Performance,” Psychological Bulletin 96 (1984):72-98. 46. John C. Loehlin. G ardner Lindzey, and J. N. Spuhler, Race Differences in Intelligence (San Francisco: W.H. Freeman, 1975), p. 169. 47. Jencks et al., Inequality, p. 179. 48. Jencks et al.. Who Gets Ahead, p. 115. 49. Samuel Bowles and Herbert Gintis, “ IQ in the U.S. Class Structure,” Social Policy (1973):65—96; Samuel Bowles and Valerie Nelson, “The 'Inheritance' of IQ and the Intergenerational Reproduction of Economic Inequality,” Review o f Economics and Statistics 56 (1974):39—51. 50. Jerome H. Waller, “Achievement and Social Mobility: Relationships Among IQ Score, Education, and Occupation in Two Generations,” Social Biology 18 (1971):252—259. 51. Anastasi. p. 144. 52. Jensen, Bias, pp. 314-315. 53. Charles Spearman, '“ General Intelligence’ Objectively Determined and Mea­ sured.” American Journal o f Psychology 15 (1904):201—292. 54. Charles Spearman. The Abilities o f Man (New York: Macmillan. 1927). 55. Anastasi, pp. 366-369. 56. L. L. Thurstone, Multiple Factor Analysis (Chicago: University of Chicago Press, 1947). 57. J. P. Guilford. The Nature o f Human Intelligence (New York: McGraw-Hill, 1967). 58. J. P. Guilford and R. Hoepfner, The Analysis o f Intelligence (New York: McGraw-Hill, 1971). 59. Sattler. p. 39. 60. Cyril Burt, “The Structure of the Mind: A Review of the Results of Factor Analysis." British Journal o f Educational Psychology 19 (1949): 100-111, 176— 199: A. R. Hakstian and R. B. Cattell, “ Higher-Stratum Ability Structures on a Basis of Twenty Primary Abilities," Journal o f Educational Psychology 70

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61.

62. 63. 64. 65. 66. 67. 68.

The IQ Controversy (1978):657—669; Lloyd G. Humphries, “The Organization of H uman Abil­ ities,” American Psychologist 17 (1962):475-483; Philip E. Vernon, The Struc­ ture o f Human Abilities, 2nd ed. (London: Methuen, 1961). John B. Carroll, “The Measurement of Intelligence,” in Robert J. Sternberg, ed., Handbook o f Human Intelligence (Cambridge, U.K.: Cambridge Univer­ sity Press, 1982), p. 73. Raymond B. Cattell, “Theory of Fluid and Crystalized Intelligence: A Critical Experiment,” Journal o f Educational Psychology 54 (1963): 1-22. A rthur R. Jensen, Straight Talk About M ental Tests (New York: Free Press 1981), p. 58. Ibid., p. 59. cf. Godfrey H. Thomson, The Factorial Analysis o f H um an Ability, 5th ed. (Boston: Houghton Mifflin, 1951); Gardner. Sattler, pp. 146-150. Anastasi, pp. 34-41; Sattler, pp. 329-333. Anastasi, p. 22.

3 The Heritability of IQ It is m eaningless to ask how m u c h o f an in d iv id u a l’s intelligence m ay be a ttrib u te d to genetic factors an d how m u c h to e n v iro n m e n t. T h e d ev elo p ­ m e n t o f intelligence, like an y o th e r aspect o f a p e rso n ’s body a n d b eh av io r (p h en otype), is as co m p letely d e p e n d e n t on genetic c o n s titu tio n (genotype) as o n en v iro n m e n t. Ju st as a fertilized o vum m u st develop in to a tr a it­ lad en h u m a n being in th e co n tex t o f som e e n v iro n m e n t, en v iro n m e n ta l stim u li c a n n o t p ro d u ce a set o f tra its w ith o u t th e p ro p er g en etic m aterial. As D o n ald H eb b has p u t it, “ To ask how m u ch h ered ity c o n trib u te s to intelligence is like asking how m u ch th e w idth o f a field c o n trib u te s to its area.” 1 T h e in ex tricab le n a tu re o f the g e n e -e n v iro n m e n t synthesis does n o t, o f course, p reclu d e th e study o f the m e ch a n ism s by w hich genes an d e n v iro n m e n t in te ract; it sim ply e lim in a te s th e possibility o f assigning an y g rea ter im p o rta n c e to o n e facto r over th e other. F ro m th is perspective, th e n a tu re /n u r tu re “ co n tro v e rsy ” is no controversy a t all. (A p ro p er u n d e r­ sta n d in g o f th e role o f genes an d e n v iro n m e n t in th e d e te rm in a tio n o f p h en o ty p ic tra its underscores th e a b su rd ity o f sta te m en ts, like th a t in the title o f th e N e w York T im e s M a g a zin e “je n se n ism ” article, th a t “ in te l­ ligence is largely d e te rm in e d by th e genes.” Intelligence is d e te rm in e d en ­ tirely by bo th th e genes an d th e en v iro n m e n t.) W h at is n o t possible to study w ithin th e in d iv id u al is o ften m e asu rab le in th e p o p u la tio n ; th e im p o rta n c e o f differences betw een p erso n s in genes a n d e n v iro n m e n t to in d iv id u al differences in an y given tra it is th eo retically a s s e s s a b le . T h e c h i e f m e a s u r e o f th is r e la tio n s h i p is h e r ita b ility . H erita b ility is defined as th e p ro p o rtio n o f v aria tio n in a tra it a ttrib u ta b le to genetic v ariatio n , a n d varies betw een 0 a n d 1.0. W h en th e h eritab ility o f a tra it is 0, it m e an s th a t all o f th e v aria tio n in th e tra it am o n g m e m b ers o f th e p o p u la tio n u n d e r study is d u e to e n v iro n m e n ta l v ariatio n . If, for e x a m ­ ple, th e h eritab ility o f IQ w as 0, it w ould m ean th a t th e difference in IQ b etw een th e genius an d the reta rd a te , o r betw een an y tw o p eople, was en tirely th e result o f different en v iro n m e n ta l experiences. T h e h eritab ility 79

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o f language spo k en , or o f religious p reference, is p ro b ab ly very n ea r 0. W hen th e h eritab ility o f a tra it is 1.0, th e p resen t range o f e n v iro n m e n ta l v aria tio n bears no rela tio n to in d iv id u al differences in th e tra it in th e p o p u la tio n u n d e r study. E ye c o lo r is a n e x a m p le o f a tr a i t w h o se h eritab ility is very n ear 1.0. V irtually all h u m a n b eh av io ral an d physical c h a r a c te r is tic s fo r w h ic h a p p r o p r ia t e s tu d ie s h av e b e e n d o n e h av e h eritab ilities betw een these tw o extrem es. Several im p o rta n t p o in ts m u st be k ep t in m in d w h en in te rp re tin g d a ta on th e h eritab ility o f IQ. F irst, h eritab ility deals w ith variation in a trait, n o t w ith ab so lu te level. It in d icates th e degree to w hich in d iv id u al d if­ feren ces in so m e tra it ca n be a ttr ib u te d to g en etic o r n o n g e n e tic d if­ ferences. T h u s, th e average IQ o f th e p o p u la tio n as a w hole can signifi­ c a n tly change as a resu lt o f so m e e n v iro n m e n ta l o r genetic ch an g es w ith o u t affecting the h eritab ility o f IQ. If ev e ry o n e’s IQ in creased by 20 p o in ts, w ith n o change in IQ variation (n o change in a n y o n e ’s IQ relativ e to th a t o f others), h eritab ility w ould re m a in th e sam e. In fact, Ja m es F ly n n has p resen ted evidence o f m assive gains in_ th e average IQ o f w hite A m eric an s betw een 1932 a n d 1978.2 (B ecause IQ is alw ays sta n d ard iz ed ac co rd in g to th e p o p u la tio n m ean , th e o n ly way to ca lcu late p o p u la tio n changes across tim e is to look at th o se in d iv id u als w ho have ta k e n at least tw o tests sta n d ard iz ed a t d ifferen t tim es. U n fo r­ tu n a te ly , e a rly s ta n d a r d iz a ti o n s a m p le s o f th e S t a n f o r d - B i n e t a n d W echsler tests did n o t in c lu d e blacks, a n d th u s F ly n n was able to co m p are o n ly th e scores o f w hite test tak ers.) Yet IQ h eritab ility estim ates calcu lated d u rin g th a t tim e p eriod did n o t change substantially, th o u g h estim ates have been so m e w h at low er in rec en t years. O n e m ay h y p o th esize th a t as th e g eneral level o f e d u c a tio n has im p ro v ed since 1932, so have th e co g nitive skills o f th e average A m eric an , w ith o u t m u c h affecting th e d istrib u tio n o f intelligence. T h e average level o f intelligence in an y p o p u la tio n is obv io u sly an im ­ p o rta n t statistic, p a rtic u la rly in an increasingly tech n o lo g ical society w here th e level o f cognitive skills necessary to c o m p ete in th e w orkplace c o n ­ tin u e s to rise. W hile h eritab ility analyses are in d e p e n d e n t o f average level o f IQ , they ca n tell us how easy o r difficult it w ould be to m ak e significant changes. By stu d y in g v aria tio n , we le arn th e rela tio n sh ip betw een in d iv id ­ ual differences in IQ an d e n v iro n m e n ta l differences betw een p eople, an d th u s have a b e tte r u n d e rsta n d in g o f th e a m o u n t o f e n v iro n m e n ta l ch an g e necessary to p ro d u c e changes in IQ. M oreover, th e stu d y o f v aria tio n in a tra it like IQ m ay be o f g reat co n seq u en ce, irresp ectiv e o f th e p o p u la tio n average. Intelligence a n d a p titu d e tests are used as d e c isio n -m a k in g tools in situ a tio n s w here e d u c a tio n a l an d o cc u p atio n al reso u rces are scarce; a c o m p etitiv e social stru c tu re is based on th e differences a m o n g peo p le in

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relev an t abilities an d attrib u tes. U n d e rsta n d in g th e causes o f th ese d if­ ferences, a n d su b seq u en tly being able to d o so m e th in g a b o u t th e m , m ay th u s have p ro fo u n d effects on th e n a tu re o f co m p e titio n a n d th e d istrib u ­ tio n o f resources a n d o p p o rtu n itie s. A second im p o rta n t p o in t a b o u t h eritab ility is th a t it is a p o p u la tio n specific statistic; it is u n iq u e to th e p a rtic u la r p o p u la tio n sam p led . In a d ifferent p o p u la tio n , o r in th e sam e p o p u la tio n a t a d ifferen t tim e, a d if­ ferent h eritab ility estim a te for the sam e tra it m ay be o b ta in e d as genetic an d en v iro n m e n ta l v aria tio n change. T h e h eritab ility o f IQ is th u s n o t fixed. As the v ariatio n in en v iro n m e n ta l ex p erien ce relev an t to p erfo r­ m a n ce on intelligence tests changes in an y p o p u la tio n , so will heritability. A very high h eritab ility for IQ th erefo re does not m ean th a t IQ c a n n o t be su b stan tia lly altered th ro u g h en v iro n m e n ta l change. It m e an s th a t u n d e r th e p resen t circ u m sta n ce s, a large en v iro n m e n ta l ch an g e (relativ e to p res­ e n t levels o f en v iro n m e n ta l v aria tio n ) is n eeded to p ro d u c e su b stan tial ch an ges in IQ. It is co m p letely possible th a t so m e new p ro g ram o f e n v iro n ­ m e n ta l m a n ip u la tio n co u ld be in tro d u c e d th a t w o u ld p ro d u c e very large ch anges in IQ in c e rta in segm ents o f th e p o p u la tio n , th u s significantly low ering heritability. T h ird , h eritab le sho u ld n o t be co nfused w ith in n a te , o r genetic. C o n sid er th e tra it o f n u m b e r o f lim bs. M ost o f us have four, an d we are in c lin e d to say th a t th is is a genetic tra it, in th a t we in h e rit it from o u r p aren ts. T h e h eritab ility o f n u m b e r o f lim bs is, however, pro b ab ly clo ser to 0 th a n it is to 1.0. T h is is because m u ch m o re o f th e variation betw een peo p le in n u m b e r o f lim bs is th e result o f en v iro n m e n ta l v aria tio n (in d u stria l accid en ts, su r­ gical a m p u ta tio n , etc.) th a n it is d u e to genetic variatio n . It is an error, o f w hich m e n tal testers historically have been guilty, to speak o f a test as m easu rin g in n a te intelligence. If th e h eritab ility o f IQ was 1.0, o n e m ight be justified in claim in g th a t differences in IQ reflect in n a te (i.e., genetic) differences, b u t it is n o t tru e th a t th e sk ills m easu red by th e test are “ in n a te ” an y m o re th a n they are “ e n v iro n m e n ta l.” T h e early m e n ­ tal testers did n o t m ak e such careful d istin c tio n s in th e ir d escrip tio n s o f th e tests. B inet h im se lf believed th a t his scale m e asu red a c o m b in a tio n o f “ intelligence p u re an d sim p le” a n d e n v iro n m e n ta lly d e te rm in e d ach iev e­ m ents. C e rta in o f th e item s in th e scale, however, p a rtic u la rly th o se d ealin g w ith p erfo rm a n c e m easu res ra th e r th a n verbal skills, he believed co u ld “ isolate from th e scholastic effects th e real n ativ e intelligence.” 3 B inet differed from m an y o f his colleagues o f th e tim e w ho, w hile c o n ­ ced ing th a t th e new intelligence tests w ere n o t u n c o n ta m in a te d by e n v iro n ­ m e n t, believed th a t intelligence itself w as fixed an d co u ld n o t be signifi­ c a n tly a lte re d by e n v ir o n m e n ta l c irc u m s ta n c e s . B in e t b e lie v e d th a t intelligence, as m easured by th e tests, co u ld be im p ro v ed , an d criticized th e

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“ b ru ta l p essim ism ” o f th o se w ho w ould forever consign th e b ack w ard child to a s u b n o rm a l life. In co n tra st, G o d d a rd , T erm an , an d o th e rs w ho revised a n d en th u sia stic ally ad m in iste re d th e tests in v ario u s in stitu tio n s in th e U n ite d States believed th em selves to be in possession o f in stru m e n ts th a t, w hile n o t perfect, p rovided a very good m easu re o f in n a te intelligence. Lew is T e rm a n ’s a ttitu d e was typical. U rging w id esp read in telligence testin g in th e schools, he argued in 1916 th a t such tests are “ n ecessary to d e te rm in e w h eth e r a given child is unsuccessful in school becau se o f p o o r n ativ e ability, o r because o f p o o r in stru c tio n , lack o f in terest, o r so m e o th e r re­ m ovable cause.”4 M an y critics o f testin g have p o in te d to sta te m e n ts o f th is so rt as ev id en ce th a t intelligence tests were, alm o st from th e begin n in g , an a tte m p t to m a in ­ ta in a caste system based o n supposed in n a te , an d th e re fo re p e rm a n e n t, differences in ability.5 (B inet is usually excepted as an in n o c e n t w hose good in te n tio n s w ere c o rru p te d by o th ers.) W h a te v er th e in te n tio n s o f th e early m e n ta l testers, o n e w ould be h a rd pressed to arg u e th a t m o d e rn p sy ch o ­ m e tricia n s h o ld such naive views o f th e role o f genes in in tellig en ce test p erfo rm an ce . T h ere is, however, w idespread m is u n d e rsta n d in g a b o u t th is issue am o n g th e general p ublic, w hich c o n tin u e s to view IQ tests as a t­ te m p ts to m easu re in n a te intelligence. T h is m isco n c ep tio n is largely responsible for th e su p p o sed stig m atizin g effects o f th e IQ (see C h a p te r 5), as well as th e p ro p ag a tio n o f o th e r aspects o f th e controversy. O n e o f th e few topics on w hich ex p e rt w itnesses o n b o th sides o f th e L a r r y P. case w ere in a g re em e n t is th a t in telligence tests are not m easu res o f in n a te ability; IQ is legitim ately a fu n ctio n o f a n in d iv id u a ls e n v iro n m e n t. Ju d g e P eckham ignored th is evidence, arg u in g th a t since th e re is no difference in “ tru e ” (i.e., in n a te ) levels o f reta rd a tio n betw een blacks a n d w hites, tests re p o rtin g such a difference m u st be biased. To th e ju d g e , as to m u c h o f th e general public, all e n v iro n m e n ta l effects on test p erfo rm a n c e rep resen t bias a n d are to be avoided. As a final p o in t a b o u t h eritab ility analyses, it sh o u ld be n o te d th a t th e h eritab ility o f IQ is co m p letely in dependent o f w h at IQ m ean s o r w hat in telligence tests m easure. T h e m e th o d s used to e stim a te th e h eritab ility o f IQ are u n rela ted to the m e th o d s used to m e asu re intelligence. T h u s if on e d ecid ed to m easu re intelligence via th e length o f th e nose, o n e co u ld o b ta in a h eritab ility e stim a te for th is intelligence m easu re. T h e validity o f th a t e stim a te o f th e h eritab ility o f nose length (like th e h eritab ility o f a score on a m o re sta n d a rd intelligence test) is in d e p e n d e n t o f w h e th e r nose len g th is an a d e q u a te m easu re o f intelligence. O n ly if o n e w ere to claim to now have an e stim a te o f th e h eritab ility o f “ in tellig en ce” w ould th e relatio n betw een nose length a n d intelligence be relevant. F or this reason, th is ch a p te r is c o n c e rn e d w ith th e h eritab ility o f IQ, an d we will look at th e q u ality o f th e

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ev id ence su p p o rtin g th is d e te rm in a tio n . T h e rela tio n sh ip o f IQ to in te l­ ligence is th e sub ject o f C h a p te r 2. U n fo rtu n a tely , h eritab ility is m u ch easier to define th a n to m easure. H eritab ility analyses are th e p ro v in ce o f th e field o f q u a n tita tiv e genetics. T h ese analyses use as th e ir d a ta th e co rre la tio n s in th e tra it being m e a­ sured, in this case IQ scores, betw een pairs o f p erson s w ho differ in genetic an d en v iro n m e n ta l relatedness. A co m m o n research design is to co m p are th e c o rre la tio n s o f m o n o zy g o tic (M Z , o r identical) tw ins, w ho have all o f th e ir genes in co m m o n , to tho se o f dizygotic (D Z , o r fra tern al) tw in s w ho have a p p ro x im ate ly h a lf o f th e ir genes in co m m o n . A h ig h er c o rre la tio n o f IQ scores for M Z th a n for D Z tw ins is tak en as stro n g ev id en ce for a gen etic so u rce o f v ariatio n . K arl H olzinger, in 1929. w as o n e o f th e first to a tte m p t a q u a n tita tiv e estim a tio n o f h eritab ility for IQ based o n tw in d a ta .6 H e suggested a m odel for h eritab ility estim a tio n based o n th e difference b e­ tw een th e co rre la tio n o f M Z tw in IQ s a n d th e co rre la tio n o f D Z tw in IQs. S im ila r fo rm u las have been p ro p o sed an d ap p lied to tw in d a ta m o re re­ cently.7 T he difficulty w ith these analyses is th a t th ey m ak e som e ra th e r sim p listic a ssu m p tio n s a b o u t th e sources o f v aria tio n in IQ. In p articu lar, th ey assum e th a t th e e n v iro n m e n ts o f M Z an d D Z tw in s are eq u ally sim ­ ilar, a n d th a t an y difference betw een M Z a n d D Z c o rre la tio n s m u st be d u e to genetic factors. G re a te r sim ilarity o f M Z e n v iro n m e n ts c o m p a re d to D Z e n v iro n m e n ts (p aren ts, teachers, a n d peers m ay tre a t id en tical tw ins m o re sim ilarly th a n they trea t fra te rn a l tw ins) is o n e o f a n u m b e r o f possible so u rces o f v ariatio n in IQ scores ignored by m a n y h eritab ility analyses. T h e e n u m e ra tio n an d e stim a tio n o f th e precise sources o f v ariatio n c o n trib u t­ ing to p h en o ty p ic v ariatio n (in th is case v ariatio n in IQ across p erso n s in a p o p u la tio n ) has been th e p rin cip al stu m b lin g block an d m a jo r so u rce o f c o n te n tio n in th e scholarly d eb a te over th e h eritab ility o f IQ.

Sources of Variation A n a n a lv sis-o f-v a ria n c e m odel, as th e n am e im plies, allow s for a m o re careful e x a m in a tio n o f th e sources o f v aria tio n in a trait. P h en o ty p ic v aria­ tio n m ay be p a rtitio n e d as follow s;8 P = G + E + f( G ,E ) w here P is p h e n o ty p ic v ariatio n , G is genetic v aria tio n . E is en v iro n m e n ta l v aria tio n , a n d f(G ,E ) is som e fu n ctio n o f th e jo in t effects o f g en o ty p e an d e n v iro n m e n t. E ach o f th e elem e n ts on th e rig h t-h a n d side o f th e e q u a to n is expressed as a p ro p o rtio n o f 1.0. It m ay be seen th a t G is th e sam e as heritability. G en e tic an d en v iro n m e n ta l variatio n m ay be eith er w ith in o r betw een

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fam ilies. S iblings (o th e r th a n iden tical tw ins) differ in b o th genes a n d e n ­ v iro n m e n t. T h is is w ith in -fa m ily v ariatio n . T otal p o p u la tio n v arian ce c o n ­ sists o f these differences an d th e differences betw een fam ilies. H erita b ility analyses reveal these sources o f v aria tio n to differing degrees. For ex am p le, stu d ies co m p a rin g M Z to D Z tw ins reflect p rim a rily w ith in -fa m ily v aria­ tio n . A d o p tio n studies, in w hich ch ild ren are m oved from o n e fam ily to an o th er, reveal th e differences betw een fam ilies. O th e r g enetic factors to be co n sid ered in c lu d e asso rtativ e m atin g , d o m i­ n an ce, a n d epistasis. A sso rtativ e m a tin g refers to th e fact th a t m a tin g is generally n o t ra n d o m w ith respect to genotype. To th e e x te n t th a t th e re is a positive co rre la tio n betw een th e gen o ty p es o f th o se w h o m ate, genetic v aria tio n will increase betw een fam ilies a n d decrease w ith in fam ilies. T h u s, if th o se w ith genes fo r higher IQ are m a tin g p rim a rily w ith each other, a n d tho se w ith genes for low er IQ are m a tin g p rim a rily w ith each other, th e v aria tio n in gen o ty p ic IQ will increase across fam ilies in th e p o p u la tio n . (N o te th a t “genes fo r higher IQ ” a n d “genes for low er IQ ” do n o t im p ly th a t th e re are specific IQ genes. I f th e re is a su b stan tia l h eritab ility fo r IQ, however, it m e an s th a t genetic v aria tio n is asso ciated w ith v aria tio n in IQ a n d , all o th e r th in g s being equal, c e rta in gen o ty p es will p ro d u ce h ig h er IQ p h e n o ty p es th a n o thers.) A t th e sam e tim e, ch ild ren will look m o re like th e ir parents. To u n d e rsta n d th is relationship, im ag in e th e m o st ex tre m e case o f asso rtativ e m ating, in w hich m ates differed o n ly in th e ir se x -d e te r­ m in in g genes. Sons o f such a p airin g w ould be id en tical g en etically to th e ir fath e r a n d d au g h ters w ould be identical to th e ir m other. D o m in a n c e decreases th e sim ilarity betw een th e p h en o ty p es o f p are n ts an d ch ild ren . G en e s co m e in pairs, a n d ch ild ren in h e rit o n e o f each p air tro m th e fath e r a n d o n e from the m other. If, for an y given gene pair, a child in h e rits a d o m in a n t gene from o n e p a re n t an d a recessive gene from th e other, only th e d o m in a n t gene will be m an ifest in th e ch ild ’s p h en o ty p e, a n d th e child will look less like th e average o f its p are n ts. P h en o ty p ic v a ria tio n will in c re ase w ith in fam ilies a n d d ecrease b etw een fam ilies. D o m in a n c e a n d asso rtativ e m a tin g will th e re fo re have o p p o site effects, an d to so m e degree cancel each o th e r o u t. T h is is fo rtu n a te , since very few analyses o f IQ h eritab ility ta k e e ith e r fac to r explicitly in to acco u n t. A n o th e r fac to r serving to decrease p a re n t-c h ild sim ilarity is epistasis, w hich is th e resu lt o f the in te ra c tio n o f genes. T h e ch ild in h e rits a u n iq u e co m b in a tio n o f genes from its p aren ts, a n d so m e o f th ese m ay in te ra c t in ways n o t p red ic tab le from th e sim ple ad d itiv e c o m b in a tio n o f th e ir sep a­ rate effects. E pistasis refers to these n o n a d d itiv e effects. E xisting ev id en ce in d icates th a t epistasis is n o t an im p o rta n t facto r in v aria tio n in IQ .9 E n v iro n m e n ta l v ariance consists o f all b e tw e e n - a n d w ith in -fa m ily dif­ ferences in e n v iro n m e n t, in c lu d in g p r e - an d p erin a tal effects, a n d e rro r

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v ariance (m e a su re m e n t error). In som e m odels, en v iro n m e n ta l v arian ce is defined as all varian ce n o t d u e to genetic factors, an d th u s in clu d es f(G,E), th e jo in t effects o f g enotype an d en v iro n m e n t. T h is m akes no difference to h eritab ility estim ates as long as h eritab ility is calcu lated by d iv id in g purely genetic v ariance by to tal variance. T h e p ro b lem is th a t som e m odels in ­ c lu d e th e se jo i n t e ffec ts as p a r t o f g e n e tic v a ria n c e , th u s in fla tin g h eritab ility estim ates. T h ere seem s to be little a g re em e n t a m o n g th o se w ho c o n d u c t beh av io r genetics stu d ies w h eth e r f(G ,E ) sh o u ld be a ttrib u te d to th e genes o r to th e e n v iro n m e n t. T h e jo in t effects o f G a n d E can ta k e tw o form s: co v arian ce an d in te ra c ­ tio n . G e n e -e n v iro n m e n t co v arian ce is rep resen ted by a c o rre la tio n b e­ tw een g enotype a n d en v iro n m e n t. T h re e types o f co v arian ce have been id e n tified ,10 passive, reactive, an d active. Passive co v arian ce o ccu rs w hen p are n ts w ho give th e ir ch ild ren genes for higher IQ, also give th e m m o re favorable e n v iro n m e n ts. In reactive covariance, oth ers, p a rtic u la rly te a c h ­ ers, m ay react to a ch ild ’s abilities by p ro v id in g m o re en ric h in g e n v iro n ­ m e n ts for tho se w ith m o re ta len t. Finally, in active co v arian ce, th e child itself, as a result o f genetic p red isp o sitio n to higher IQ , m ay actively seek o u t m o re in tellectu ally stim u la tin g situ atio n s. G e n e -e n v iro n m e n t c o rre la ­ tio n m ay also be negative, o f course, as w hen te ach ers try to p rovide th e m o st stim u la tin g e n v iro n m e n ts to tho se w ho seem to need th e m m ost. P ositive co v arian ce will act to p ro d u ce greater p h en o ty p ic variab ility th a n w ould be p re d ic ta b le fro m gen etic a n d e n v iro n m e n ta l v a ria tio n alo n e. D avid Layzer has argued th a t co v ariatio n is always p resen t to an u n k n o w n degree in h u m a n b eh a v io r-g e n etic studies, th u s in v a lid a tin g an y a tte m p ts to sep arate genetic from en v iro n m e n ta l in flu en ces.11 N o n e th e ­ less, m an y h eritab ility analyses have a tte m p te d to e stim a te th e e x te n t o f covariance. R o b e rt P lo m in an d his colleagues have d e m o n stra te d th a t th e p ro b lem is statistically soluble, b u t claim th a t th e n ecessary d a ta are at p re se n t la c k in g .12 T h e re is th e re fo re a g reat deal o f in d e te rm in a c y in co v ariance estim ates, w hich can have a p ro fo u n d effect on h eritab ility calcu latio n s. For exam ple, Je n ck s et al., based on th e ir an aly sis o f sources o f v ariatio n in b e h a v io r-g e n e tic studies o f IQ , ca lc u lated th a t g e n e -e n ­ v iro n m e n t covariance ac c o u n ts for 20 p erc en t o f to ta l p h en o ty p ic v ari­ ance, an d derived a h eritab ility estim a te o f 0 .4 5 .13 L o eh lin , Lindzey, a n d S p u h ler suggesting a lte rn a tiv e h y potheses o f g e n e -e n v iro n m e n t rela tio n s in Je n ck s et al.'s d ata, p ro d u ce an equally plausible co v arian ce estim a te o f 15 p ercen t, leading to a h eritab ility ca lc u latio n o f a b o u t 0 .6 0 .14 T h e situ a ­ tio n is fu rth e r co m p lic ate d by stu d ies th a t do n o t a tte m p t to estim a te co v arian ce at all, leading to inflated e stim a tes o f G , E, o r b o th .15 R elated to covariance is g e n e -e n v iro n m e n t in te ra c tio n , w hich refers to th e differential effects o f c e rta in e n v iro n m e n ts on c e rta in genotypes. In

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o th e r w ords, an in te ra c tio n occurs w hen genoty p es a n d e n v iro n m e n ts are n o t ad d itiv e in th e ir effects. T h u s, it m ay be th a t in d iv id u als w ith genes for low er IQ profit m o re from a c e rta in e n v iro n m e n t th a n th o se w ith genes for h igher IQ, o r vice versa. R ich a rd L ew ontin p o in ts o u t th a t th e p resen ce o f g e n e -e n v iro n m e n t in te ra c tio n severely lim its th e u sefulness o f h eritab ility an a ly se s.16 W h a t is really desired, he argues, is th e n o rm o fre a c tio n , w hich d escribes th e p h en o ty p ic o u tc o m e o f all possible g e n e -e n v iro n m e n t c o m ­ b in a tio n s. Since h eritab ility analyses are based on o n ly a sm all n u m b e r o f these c o m b in a tio n s (those p resen t in th e p o p u la tio n being studied), th e results o f an y given analysis m ay only be generalized if each e n v iro n m e n t h as th e sam e effect on d ifferent g enotypes— in o th e r w ords, if g e n e - e n ­ v iro n m e n t effects are additive. W hile th e re are few good tests o f in te ra c tio n effects, p a rtic u la rly in tw in stu d ie s,17 at least fo u r review s o f th e lite ra tu re have been u n ab le to find an y evidence for significant g e n e -e n v iro n m e n t in te ra c tio n s in IQ .18 To d ate, few h eritab ility analyses o f IQ have in c lu d ed a specific in te ra c tio n term . P hilip V ernon has p resen ted th e follow ing c h a rt as a way o f su m m arizin g th e several sources o f varian ce c o n trib u tin g to p h en o ty p ic v a ria tio n :19 G betw een fam ilies G w ithin fam ilies A M (asso rtativ e m a tin g betw een paren ts) D (d o m in a n ce)

G

G - E co v arian ce (effects o f co v a riatio n betw een G an d E) G - E in te ractio n

f(G ,E )

E betw een fam ilies E w ith in fam ilies E e (e rro r o r u n reliab ility variance) T h e m o re ac cu rately such factors as d o m in a n c e , asso rtativ e m atin g , co variance, a n d in te ra c tio n can be estim a ted , th e m o re a c cu rate will be su b se q u en t m easu res o f heritability. We have seen th a t early h eritab ility analyses to o k n o n e o f these factors in to ac co u n t. M o d e rn in v estig atio n s have a tte m p te d to deal w ith these variables, som e m o re co m p letely th a n others. T h e state o f th e b e h a v io r-g e n e tic a r t is rep rese n ted by b io m e trica l an a ly ­ sis, w hich a tte m p ts to m odel th e sources o f v aria tio n a m o n g th e n u m e ro u s g enetic an d en v iro n m e n ta l rela tio n sh ip s in an y given b eh a v io r-g e n etic study.20 B iom etrical analysis is ad v an tag eo u s in th a t it allow s for statistical tests o f th e e x te n t to w hich each o f th e factors listed above is im p o rta n t to

The Heritability of IQ

87

th e analysis at h an d . In d e te rm in a c y persists, however, becau se sufficient d a ta are n o t always available to c o n d u c t all th e necessary tests, an d because an alysts m ay disagree a b o u t th e way v ariance is p a rtitio n e d in th e ir original m odel. Je n ck s et al. w ere o n e o f the first to ap p ly a p ath analysis to b e­ h av io r-g e n e tic d a ta in o rd e r to a c c o u n t for th e rela tio n sh ip betw een th e in telligence o f p a re n ts a n d child ren . As m e n tio n e d , L o eh lin an d his co l­ leagues w ere able to derive a very different h eritab ility estim a te from th e sam e d a ta by assu m in g th a t ad o p tiv e p are n ts’ intelligence affects th e ch ild ’s e n v iro n m e n t directly, ra th e r th a n via the ad o p tiv e p are n ts’ gen o ty p e, as in Je n ck s et al.’s m odel. Such a ssu m p tio n s are largely arb itrary , an d can p ro ­ d u ce q u ite varied results.21 T h e h eritab ility analyses to be discussed vary in th e degree to w hich th ey deal w ith different sources o f bias, a n d in th e ir u n d erly in g m odels. M o re­ over, th e q u ality o f b e h a v io r-g e n e tic d a ta has been lim ite d by such factors as p o o r sam p lin g p ro ce d u re s a n d th e in stab ility o f test scores across age groups. It should n o t be surprising, therefo re, th a t estim ates o f h eritab ility also vary. T h e best o n e can ho p e for at th is p o in t is ev id en ce for or ag ain st a significant genetic c o m p o n e n t o f differences in test scores, a n d a ran g e o f h eritab ility estim ates. T h e D ata Figure 3.1, ta k en from a 1981 review by T h o m a s B o u ch ard an d M atth ew M cG ue, su m m arize s th e results o f 111 b e h a v io r-g e n e tic stu d ies o f m e a­ su red intelligence, rep resen tin g th e vast m a jo rity o f all such stu d ies ever d o n e .22 Each p o in t rep resen ts th e c o rre la tio n , from o n e study, betw een intelligence test scores o f p ersons o f the in d icated gen etic a n d e n v iro n m e n ­ tal relatedness. T h e vertical b a r th ro u g h each d istrib u tio n rep resen ts th e m e d ia n c o rre la tio n from all stu d ies o f th a t typ e. T h u s, for ex a m p le , B o u chard an d M cG u e p resent th e results o f 41 stud ies o f th e IQ co rrela tio n o f D Z tw ins reared to g e th er (line 5 in th e figure), rep resen tin g 5,546 p airs o f D Z tw ins. T h e m e d ian IQ c o rre la tio n across these stu d ies is 0.58. A m o re m ean in g fu l statistic th a n th e m e d ian is th e w eighted average, w hich takes in to a c c o u n t differences in sam p le size betw een in v estig atio n s, an d is given in o n e o f th e co lu m n s on th e right side o f th e figure. C o rre la ­ tio n coefficients from studies involving larger n u m b e rs o f subjects are given m o re w eight in ca lcu latin g th e average c o rre la tio n . F or D Z tw in s reared a p a rt, this average is 0.60. T h e arro w u n d e r each d istrib u tio n in d icates th e p red icted co rrela tio n o f a sim ple polygenic m odel, assu m in g th a t all p h en o ty p ic v aria tio n in IQ is d u e to ad d itiv e gen etic effects (no d o m in a n c e o r epistasis), w ith no assortativ e m ating. IQ heritab ility u n d e r such a m odel is 1.0.

0.0

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

MONOZYGOTIC TWINS REARED APART

• MIDPARENT-MIDOFFSPRING REARED TOGETHER

\

I

MIDPARENT-OFFSPRING REARED TOGETHER

4672

.85

.86

3

65

.67

.72

0.92 (2)

0.46

3

410

.73

.72

2.66 (2)

1.33

8

992

.475

.50

8.11 (7)

1.16

.60

94.5 (40)

2.36

6.31

41

SIBLINGS REARED TOGETHER

*

SIBLINGS REARED APART

•I* 1

SINGLE PARENT-OFFSPRING REARED TOGETHER

k

5546

.58

69

26,473

.45

.47

403.6 (64)

2

203

.24

.24

.02

32

8433

.385

.42

4

814

.22

.22

~

2.46

.02

(1)

211.0 (31)

6.81

9.61 (3)

3.20

A

SINGLE PARENT-OFFSPRING REARED APART

1 1

HALF SIBLINGS

.

COUSINS

.

NON BIOLOGICAL SIBLING PAIRS (ADOPTED/NATURAL PAIRINGS)

‘

.

.1 .

*1

r

a

1

A ADOPTING MIDPARENT-OFFSPRING

. it. 1

A ADOPTING PARENT-OFFSPRING

.

..

200

.35

.31

4

1,176

.145

.15

1.02 (2)

0.51

5

345

.29

.29

1.93 (4)

0.48

6

369

.31

.34

10.5 (5)

2.10

.24

6.8 (5)

1.36

1.33

6.41

6

758

.19

.

t.

* o!o

(1)

6

1397

.18

19

6.64 (5)

16

3817

.365

.33

96.1 (15)

A ASSORTATIVE MATING

1.55

2

|

A

NON-BIOLOGICAL SIBLING PAIRS (ADOPTEO/ADOPTEO PAIRINGS)

34

-----

A

|

X2 d.f.

81.29