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Cited by 48Cognitive Abilities and TestingRace, Genetics, and SocietyIntergenerational and Educational Inequality Studies

Race and IQ: A Theory-Based Review of the Research in Richard Nisbett - s Intelligence and How to Get It

Open access
Rushton, J. Philippe, Jensen, Arthur R.·2010·The Open Psychology Journal
DOI 10.2174/1874350101003010009
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Abstract

We provide a detailed review of data from psychology, genetics, and neuroscience in a point-counterpoint format to enable readers to identify the merits and demerits of each side of the debate over whether the culture-only (0% genetic- 100% environmental) or nature + nurture model (50% genetic-50% environmental) best explains mean ethnic group differences in intelligence test scores: Jewish (mean IQ = 113), East Asian (106), White (100), Hispanic (90), South Asian (87), African American (85), and sub-Saharan African (70). We juxtapose Richard Nisbett ’ s position, expressed in his book Intelligence and How to Get It , with our own, to examine his thesis that cultural factors alone are sufficient to explain the differences and that the nature + nurture model we have presented over the last 40 years is unnecessary. We review the evidence in 14 topics of contention: (1) data to be explained; (2) malleability of IQ test scores; (3) cultureloaded versus g-loaded tests; (4) stereotype threat, caste, and “X” factors; (5) reaction-time measures; (6) within-race heritability; (7) between-race heritability; (8) sub-Saharan African IQ scores; (9) race differences in brain size; (10) sex differences in brain size; (11) trans-racial adoption studies; (12) racial admixture studies; (13) regression to the mean effects; and (14) human origins research and life-history traits. We conclude that the preponderance of evidence demonstrates that in intelligence, brain size, and other life history traits, East Asians average higher than do Europeans who average higher do South Asians, African Americans, or sub-Saharan Africans. The group differences are between 50 and 80% heritable.

AI snapshot

Written from the paper’s full text.

TL;DR

This point-counterpoint review argues against Richard Nisbett’s culture-only explanation of race/IQ differences and for a nature + nurture model in which group differences in intelligence, brain size, and life-history traits are substantially heritable. The authors conclude that East Asians average higher than Europeans, who average higher than South Asians, African Americans, or sub-Saharan Africans, with group differences between 50 and 80% heritable.

Key findings

  • The paper reports mean IQ estimates of Jewish = 113, East Asian = 106, White = 100, Hispanic = 90, South Asian = 87, African American = 85, and sub-Saharan African = 70, and states the U.S. Black-White gap is about 15–18 points (1.0–1.1 SD); a cited meta-analysis by Roth et al. found a 1.1 SD difference across 6,246,729 testees.
  • The authors dispute Nisbett’s claim that the Black-White IQ gap narrowed by 5.5 points from 1972–2002; they calculate a 3.4-point gain from the tests Dickens and Flynn used, and 2.1 points when four omitted tests are included.
  • They argue Black-White differences are larger on more g-loaded and more heritable subtests, citing correlations such as g loadings predicting Black-White differences (r = .62) and inbreeding depression correlating with Black-White differences (r = .48).
  • They report race differences in brain size (East Asians = 1,364 cm³, Whites = 1,347, Blacks = 1,267) and in the Minnesota Trans-Racial Adoption Study at age 17 (adopted White IQ = 106, Mixed-Race = 99, Black = 89), concluding the preponderance of evidence supports a 50–80% heritable group difference.

Methods

  • Design: a point-counterpoint review of 14 topics, juxtaposing Nisbett’s *Intelligence and How to Get It* with the authors’ hereditarian nature + nurture position.
  • Data: published psychology, genetics, and neuroscience studies, including twin/adoption studies, reaction-time measures, MRI/autopsy/skull-size data, national IQ compilations, and meta-analyses; the authors also report a reanalysis of Rushton et al.’s item-heritability data into six parcels, yielding r = .47 and mean r = .74.
  • Analysis: narrative and quantitative synthesis, including correlated vectors, principal components analysis, and comparisons of effect sizes across studies; no systematic review protocol is described.

Limitations

  • The paper states no formal limitations section.
  • Evident from the text: it is an adversarial review written by longstanding proponents of the hereditarian model and critics of Nisbett, so the selection and interpretation of evidence are partisan.
  • Evident from the text: it relies heavily on the authors’ own prior work and on some unpublished manuscripts/personal communications, and it does not describe systematic inclusion criteria or a pre-specified meta-analytic protocol.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.2174/1874350101003010009

Cites

209 of 209 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 267 cited sources checked · 0 supported · 0 flagged

  • Findingcitation

    Dickens and Flynn excluded several tests that showed small or negative Black gains, including the Wonderlic Personnel Test, the Kaufman Assessment Battery for Children, the Woodcock-Johnson test, and the Differential Ability Scale.

    “Dickens and Flynn excluded the Wonderlic Personnel Test, which showed a gain of only 2.4 points for Blacks between 1970 and 2001; the Kaufman Assessment Battery for Children (K-ABC), which showed a loss of 1 IQ point for Blacks between 1983 and 2004; the Woodcock-Johnson test, which showed a zero gain for Blacks; and the Differential Ability Scale, which showed a gain of only 1.83 points for”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Rushton and Jensen [25]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Findingcitation

    In Rushton et al. Study 2, heritabilities for 58 SPM puzzles from 152 adult MZ/DZ twin pairs correlated with pass-rate differences for 11 diverse samples at overall mean r = .40, P < .05.

    “In Study 2, 152 pairs of adult MZ and DZ twins from the Minnesota Study of Twins Reared Apart provided heritabilities for 58 puzzles from the SPM.These correlated with the differences in pass rates calculated for 11 diverse samples, including the Roma in Serbia, and Asian, White, Colored, and Black students in South Africa (overall mean r = .40;P < .05).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [63]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Findingcitation

    In Rushton et al. Study 1, heritabilities for 36 CPM puzzles from 199 MZ/DZ twin pairs correlated with pass-rate differences between twins and 94 Roma in Serbia at r = .32, P < .05.

    “In Study 1, 199 pairs of 5-to 7-year-old monozygotic (MZ) and dizygotic (DZ) twins reared together provided heritabilities for 36 puzzles from the CPM.These correlated with the differences in pass rates between the twins and 94 Roma (Gypsies) living in Serbia (r = .32;P < .05).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [63]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Findingnone given

    It is a false claim that g and inbreeding depression correlate with the secular rise in IQ.

    “However, it is a false claim that g and inbreeding depression correlate with the secular rise in IQ.”
    Quote in the paperNot a substantial claim
  • Findingnone given

    Items found relatively difficult or easy for twins in North America are the ones found relatively difficult or easy by the Roma in Serbia and by Whites, Asians, Coloreds, and Blacks in South Africa, with mean r = .87.

    “For example, items found relatively difficult (or easy) for twins in North America are the ones found relatively difficult (or easy) by the Roma in Serbia and by the Whites, Asians, Coloreds, and Blacks in South Africa (mean r = .87).”
    Quote in the paperSubstantial claim
  • May combine two claims. 86
  • Classified as probably not a substantial claim. 27

  • May combine two claims.

    Findingcitation

    Simple arithmetic applied to Dickens and Flynn's test data yielded a mean Black gain of 3.4 points (23%), not the 5.5 points claimed (37%); including the omitted tests reduced the gain to 2.1 points (14%).

    “Simple arithmetic, rather than a multiplied projection, yielded a mean gain for Blacks of 3.4 points (23%), not the 5.5 points claimed (37%).Including the aforementioned tests reduced the gain from 3.4 to 2.1 points (14%).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Rushton and Jensen [25]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingcitation

    Flynn's revised analyses discarded the WISC Maze subtest, discarded the gain scores and Black-White differences on the WISC-III, averaged the five sets of gain scores, and calculated a new g loading for the Wechsler subtests from Raven's Progressive Matrices.

    “Flynn: (a) discarded the WISC Maze subtest, thereby reducing the number of WISC subtests from 11 to 10 (no reason given); (b) discarded the gain scores and Black-White differ-ences on the WISC-III on the grounds that most of the data were on the WISC-R; (c) averaged the five sets of gain scores on the grounds that five gain indicators were too many for Rushton's factor analysis to be fair (though”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Flynn [32]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingcitation

    In Rushton's more complete analysis, inbreeding depression correlated positively with Black-White differences (r = .48; P < .05) and with g loadings from WISC-R and WISC-III (.61, .39) but not with the five sets of gain scores (mean r = .13; range = -.07 to .29).

    “As can be seen, inbreeding depression correlated positively with the Black-White differences (r = .48;P < .05)and also with the g loadings from the WISC-R and WISC-III (.61, .39)but not with the five sets of gain scores (mean r = .13;range = -.07 to .29).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Rushton [43]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingcitation

    Rushton's principal components analysis found that IQ gains on the WISC-R and WISC-III form a cluster, showing the secular trend in overall test scores is a reliable phenomenon, but this cluster is independent of a second cluster formed by Black-White differences, inbreeding depression scores, and g factor-loadings.

    “The relevant findings are: (1) the IQ gains on the WISC-R and WISC-III form a cluster, showing that the secular trend in overall test scores is a reliable phenomenon; but (2) this cluster is independent of a second cluster formed by Black-White differences, inbreeding depression scores (a purely genetic effect), and g factor-loadings (a largely genetic effect).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Rushton [43]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingcitation

    The two sets of g loadings correlated significantly positive with Black-White differences (.53, .69) but significantly negative with the 10 sets of gain scores (mean r = -.33; range from -.04 to -.73; P < .00001).

    “The two sets of g loadings correlated significantly positive with the Black-White differences (.53, .69)but significantly negative with the 10 sets of g loadings (mean r = -.33;range from -.04 to -.73; P < .00001;Fisher [44], pp.99-101).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Rushton [43]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingcitation

    Flynn's new correlations were not significant with N = 10: .50 between g and secular gains, .28 between inbreeding depression and secular gains, .50 between g and Black-White differences, and .29 between inbreeding depression and Black-White differences.

    “Although none of Flynn's new correlations were significant with N = 10: .50 between g and secular gains (reversing Rushton's highly significant finding of -.33); .28 between inbreeding depression and secular gains (up from Rushton's in effect zero .13);.50 between g and Black-White differences (down from Rushton's significant correlation of .61);and.29 between inbreeding depression and Black-White”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Flynn [32]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingnone given

    Even on very simple RT tests, children with higher IQ scores perform faster than children with lower scores, and East Asian 9- to 12-year-olds are faster than Whites who are faster than Blacks.

    “Yet even on these very simple tests, children with higher IQ scores perform faster than do children with lower scores, and East Asian 9-to 12-year-olds are faster than Whites who are faster than Blacks.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingcitation

    The Dickens and Flynn models have been criticized for having too many free parameters and for ignoring the cross-cultural generalizability of Black-White differences on the g factor.

    “The Dickens and Flynn models have also been criticized for having too many free parameters and for ignoring the cross-cultural generalizability of Black-White differences on the g factor [8, 95, 96].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [8]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [95]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [96]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingnone given

    Almost all the data show that the size of the Black-White IQ gap remains constant at 1 SD, with no significant change after about three years of age.

    “Yet almost all the data show that the size of the Black-White IQ gap remains constant at 1 SD, with no significant change after about three years of age.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingcitation

    Osborne tested the hypothesis by comparing several hundred pairs of Black and White twins aged 12 to 18 on three tests and found heritabilities of about 50% in each group.

    “However, when Osborne [89] tested this hypothesis empirically by comparing several hundred pairs of Black and White twins aged 12to 18-years on the Basic Test Battery, the Primary Mental Abilities test, and the Cattell Culture Fair Intelligence test.He found heritabilities of about 50% in each group.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [89]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Classified as probably not a substantial claim.

    Findingcitation

    Although adoption studies demonstrate IQ gains, they typically fail to examine whether the gain is on the g factor.

    “He further noted that although adoption studies demonstrate IQ gains, they typically fail to examine whether the gain is on the g factor”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [22]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingcitation

    In the five-country data, East Asian children obtained the highest IQs, followed by White children, then Black children; median speed on three RT tasks followed the same order, as did their SDs, with the highest scoring group being least variable.

    “The East Asian children obtained the highest IQs, followed by the White children, and then the Black children.The median speed for the three reaction time tasks followed the same order, as did their SDs, with the highest scoring group being the least variable.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [13]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingcitation

    On the Progressive Matrices, Wicherts et al. raised the mean from 70 to 78; on other tests they raised the mean from 70 to 81.

    “On the Progressive Matrices, they raised the mean from 70 to 78; on other tests such as the Draw-A-Man test, the Kaufman Assessment Battery for Children, and the Wechsler scales, they raised the mean from 70 to 81.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [97]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [98]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingcitation

    Most studies have found no interaction effects or interactions that vary unpredictably.

    “However, most studies have found no interaction effects or interactions that vary unpredictably.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingcitation

    In Rowe et al. longitudinal data, analyses showed correlation matrices were equivalent across White, Black, and Hispanic groups with no evidence of Factor X affecting academic achievement or developmental changes.

    “Analyses again showed the matrices were equivalent across the groups with no evidence of any Factor X affecting academic achievement or developmental changes of any group.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [69]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Classified as probably not a substantial claim.

    Findingcitation

    Lynn concluded that the best estimate of African IQ remains 70.

    “Lynn concluded that the best estimate of African IQ remains 70.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [101]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [102]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Findingnone given

    Many RT tasks are so easy that 9- to 12-year-old children can perform them in less than one second.

    “Many RT tasks are so easy that 9-to 12-yearold children can perform them in less than one second.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingcitation

    Rowe and Cleveland's best fitting model for all the data was one whereby the sources of differences between individuals within race and differences between races were the same-50% genetic and 50% environmental.

    “The best fitting model for all the data was one whereby the sources of the differences between individuals within race and the differences between races were the same-50% genetic and 50% environmental.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [94]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingcitation

    Differences between Blacks, Whites, and East Asians in RTs are largely on the g factor, with correlations between g loadings and mean group differences ranging from .70 to .81.

    “Moreover, the differences between Blacks, Whites, and East Asians in RTs are largely on the g factor, with the correlations between the g loadings and the mean group differences ranging from .70 to .81 [75,76].”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [75]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [76]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingcitation

    The Black and White correlation matrices were nearly identical and as alike as matrices computed from random halves within groups.

    “Not only were the Black and White matrices nearly identical, they were as alike as the matrices computed from random halves within groups.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [68]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingcitation

    In Osborne's data, heritabilities on the Basic, Primary, and Cattell tests were, respectively: Whites .61, .37, .71; Blacks .75, .42, .19.

    “The heritabilities in the Basic, Primary, and Cattell tests were, respectively: Whites-.61,.37,and .71;Blacks-.75, .42,and .19.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [89]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingcitation

    After training, the Tanzanian children's scores improved but only to about the 9th percentile on American norms (IQ < 80).

    “After training on how to solve problems like those on the test, the children's scores improved, but only to about the 9th percentile on American norms (IQ < 80).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [106]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingcitation

    Lynn's reviews covered over two dozen studies from West, Central, East, and Southern Africa, all of which found a low average IQ.

    “Lynn's [11,14] reviews covered over two dozen studies from West, Central, East, and Southern Africa, all of which found a low average IQ.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [11]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [14]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingcitation

    Within Africa, Asia, and Europe separately, IQ correlated negatively with skin color (r = -.86, -.55, and -.63 respectively).

    “The correlation between IQ and skin color remained even when calculated separately within each of three continents: Africa, -.86; Asia, -.55; Europe, -.63.”
    Quote in the paperSubstantial claim0 of 4 sources checked
    • cites [172]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [173]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [174]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [175]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • Rests on an assumption: IQ tests measure the same cognitive ability across racial and ethnic groups.
    • Rests on an assumption: Skin color is a valid proxy for genetic admixture.

  • Classified as probably not a substantial claim. May combine two claims.

    Findingcitation

    Absolute latitude correlated -.88 with skin color and .78 with IQ; mean winter temperature correlated .71 with IQ.

    “while absolute latitude correlated -.88 with skin color and .78 with IQ, as with mean winter temperature (r = .71).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Templer [174]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • Rests on an assumption: IQ tests measure the same cognitive ability across racial and ethnic groups.
    • Rests on an assumption: Skin color is a valid proxy for genetic admixture.

  • May combine two claims.

    Findingcitation

    The two sets of Mixed-Race children in Willerman et al. averaged an IQ of 98, intermediate to the White and Black children in the larger sample (IQs = 105 and 91, respectively).

    “Nisbett also neglected to mention that the two sets of Mixed-Race children averaged an IQ of 98, intermediate to the White and Black children in the larger sample from whom they had been drawn (IQs = 105 and 91, respectively; [177, p. 43].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [177]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • Rests on an assumption: IQ tests measure the same cognitive ability across racial and ethnic groups.

  • May combine two claims.

    Findingcitation

    In Eyferth's study, the mean IQ of 83 White children was 97.2 and of 98 Mixed-Race children was 96.5.

    “The mean IQs for 83 White children and for 98 Mixed-Race children were both about 97 (97.2 for the Whites, 96.5 for the Mixed-Race).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Eyferth [166]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • Rests on an assumption: IQ tests measure the same cognitive ability across racial and ethnic groups.

  • Classified as probably not a substantial claim. May combine two claims.

    Findingcitation

    In Willerman et al.'s study, White mothers averaged almost a year more schooling than Black mothers and so likely had a higher IQ.

    “Thirty-five years ago, Loehlin et al. [2, p. 126] pointed out that the White mothers averaged almost a year more schooling than the Black mothers and so likely had a higher IQ.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Loehlin et al. [2]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • Rests on an assumption: IQ tests measure the same cognitive ability across racial and ethnic groups.

  • May combine two claims.

    Findingcitation

    In the National Longitudinal Study of Adolescent Health, Black adolescents averaged lower verbal IQ than White adolescents, with Mixed-Race adolescents falling in between.

    “Similarly, Rowe [171] examined the National Longitudinal Study of Adolescent Health and found the Black adolescents averaged a lower verbal IQ than the White adolescents, with the Mixed-Race group falling in between.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Rowe [171]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • Rests on an assumption: IQ tests measure the same cognitive ability across racial and ethnic groups.

  • May combine two claims.

    Findingcitation

    Skin color ratings and actual skin reflectance measures correlated -.96 with each other, and both correlated about .90 with IQ scores.

    “Moreover, Templer [174] found the ratings of skin color and actual skin reflectance measures correlated with each -.96 and both correlated with IQ scores about .90”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Templer [174]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • Rests on an assumption: IQ tests measure the same cognitive ability across racial and ethnic groups.
    • Rests on an assumption: Skin color is a valid proxy for genetic admixture.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingcitation

    People of East Asian and African ancestry fall at the two ends of a continuum, with Europeans falling intermediate in speed of maturation and longevity, personality and temperament, family stability and crime, and sexual behavior and fertility.

    “People of East Asian and African ancestry fall at the two ends of a continuum, with Europeans falling intermediate in speed of maturation and longevity, personality and temperament, family stability and crime, and sexual behavior and fertility [23].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Rushton [23]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingcitation

    Black babies sit, crawl, walk, and put on their clothes earlier than do White or East Asian babies.

    “Another example: Black babies sit, crawl, walk, and put on their clothes earlier than do White or East Asian babies.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Rushton [23]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingcitation

    Any decrease in average brain size over the past 35,000 years within Homo sapiens has been paralleled by a corresponding decrease in average body size, suggesting no decrease in relative encephalization.

    “According to analyses by Ruff and colleagues [182,183], any decrease in average brain size over the past 35,000 years within Homo sapiens has been paralleled by a corresponding decrease in average body size, suggesting no decrease in relative encephalization.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Ruff and colleagues [182,183]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingcitation

    Cranial capacity increases linearly with degree of latitudinal deviation north from the equator (r = .60), with 87% of the latitudinal variation predicted by differences in mean annual temperatures.

    “According to Bailey and Geary [184], cranial capacity increases linearly with degree of latitudinal deviation north from the equator (r = .60),with 87% of the latitudinal variation predicted by differences in mean annual temperatures.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Bailey and Geary [184]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingcitation

    The milestones for walking are: East Asians, 13 months; Whites, 12 months; Blacks, 11 months.

    “The milestones for walking are: East Asians, 13 months; Whites, 12 months; Blacks, 11 months.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Rushton [23]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingcitation

    Head Start programs produced modest gains in school retention and graduation rates among Whites but not Blacks.

    “Head Start programs did produce modest gains in school retention and graduation rates among Whites-but not Blacks [193].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [193]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingcitation

    Mixed-race children of Japanese-Black ancestry develop faster than mixed-race Japanese-White children and especially than children with two Japanese parents.

    “These racial-group differences are heritable: mixed-race children of Japanese-Black ancestry develop faster than do mixed-race Japanese-White children and especially than do children with two Japanese parents [189].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [189]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingcitation

    The tendency to produce dizygotic twins is heritable through the race of the mother and is mediated by sex hormones.

    “The tendency to produce dizygotic twins is heritable through the race of the mother and is mediated by sex hormones [23,188].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Rushton [23]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [188]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingcitation

    After controlling for body weight and body length, brain size continued to predict the other variables (r = .59).

    “Even after controlling for body weight and body length, brain size continued to predict the other variables (r = .59).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Rushton [187]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingcitation

    Rushton documented that the races differed not only in brain size and intelligence but also on a suite of 60 life-history characters.

    “In Race, Evolution, and Behavior, Rushton [23] documented that the races differed not only in brain size and intelligence but also on a suite of 60 life-history characters (Table 5).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Rushton [23]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingcitation

    Blacks average an earlier age of sexual maturity than Whites, who in turn have an earlier age than East Asians, whether measured by age of first menstruation, first sexual experience, or first pregnancy.

    “Blacks also average an earlier age of sexual maturity than do Whites, who in turn have an earlier age than do East Asians, whether measured by age of first menstruation, first sexual experience, or first pregnancy [23].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Rushton [23]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingcitation

    Across 234 mammalian species, brain weight correlated with longevity (r = .70), gestation time (.72), birth weight (.44), litter size (-.43), age at first mating (.63), duration of lactation (.62), body weight (.44), and body length (.54).

    “Rushton [187] found empirical support for the predicted relationships across 234 mammalian species: brain weight correlated with longevity (r = .70),gestation time (.72), birth weight (.44), litter size (-.43),age at first mating (.63), duration of lactation (.62), body weight (.44), and body length (.54).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Rushton [187]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingcitation

    An individual's racial group can be determined by testing DNA at 100 random sites along the genome, or at 30 specifically chosen ones.

    “On the basis of existing surveys, an individual's racial group can be determined by testing his or her DNA at 100 random sites along the genome, or at 30 specifically chosen ones [179].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [179]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Findingcitation

    The rate of dizygotic twinning is less than 4 per 1,000 births among East Asians, 8 among Whites, and 16 or greater among Blacks.

    “It is striking that around the world the rate of dizygotic (also termed two-egg, fraternal, or nonidentical) twinning is: less than 4 per 1,000 births among East Asians; 8 among Whites; 16 or greater among Blacks.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Rushton [23]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisecitation

    In the developed world, IQ scores increased markedly from 1947 to 2002, on average about 3 points a decade over the last 50 years, and the mean went up by 18 points in the US alone.

    “In the developed world, IQ scores increased markedly from 1947 to 2002-on average, about 3 points a decade over the last 50 years [16][17][18].The mean went up by 18 points in the US alone.”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [16]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [17]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [18]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisecitation

    The average IQ of Black draftees in World War I was 83, versus 100 for Whites, with 13% of Blacks overlapping the White mean.

    “The 23,596 Black draftees had an IQ of 83 (vs. 100 for Whites), with 13% of Blacks overlapping the White mean.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Shuey [6]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisecitation

    The 15-point Black-White IQ difference was consistent in student groups from preschool to college, in the armed forces, and in specific groups such as delinquents, criminals, the gifted, and the developmentally challenged.

    “She found the 15 point difference was consistent in student groups from preschool to college, as well as in members of the armed forces and specific groups such as delinquents, criminals, the gifted, and the developmentally challenged.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Shuey [6]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Interpretationnone given

    The preponderance of evidence demonstrates that in intelligence, brain size, and other life history traits, East Asians average higher than Europeans, who average higher than South Asians, African Americans, or sub-Saharan Africans.

    “We conclude that the preponderance of evidence demonstrates that in intelligence, brain size, and other life history traits, East Asians average higher than do Europeans who average higher do South Asians, African Americans, or sub-Saharan Africans.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Premisecitation

    The average IQ for Jewish-Americans was higher than for East Asian-, White-, Latino-, and African-Americans (113, 106, 103, 89, and 85, respectively).

    “The study also showed that the average IQ for Jewish-Americans was higher than for East Asian-, White-, Latino-, and African-Americans (113, 106, 103, 89, and 85, respectively, pp.273-278).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Herrnstein and Murray [7]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisecitation

    Lynn's collation of 620 studies (N = 813,778) found a world average IQ of 90, with East Asians highest at 105, followed by Europeans (100), Inuit-Eskimos (91), South East Asians (87), Native American Indians (87), Pacific Islanders (85), South Asians & North Africans (84), sub-Saharan Africans (67), Australian Aborigines (62), and Kalahari Bushmen & Congo Pygmies (54).

    “Lynn tabulated 620 studies from the beginning of the twentieth century to the present (N = 813,778) and found the world average IQ to be 90 (Fig. 1).The East Asian cluster (Chinese, Japanese and Koreans) obtained the highest mean IQ at 105, followed by Europeans (100), Inuit-Eskimos (91), South East Asians (87), Native American Indians (87), Pacific Islanders (85), South Asians & North Africans (”
    Quote in the paperSubstantial claim0 of 4 sources checked
    • cites [11]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [12]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [13]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [14]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisecitation

    A test's g loading is the best predictor of that test's correlation with scholastic and work-place performance and of biological measures such as heritability coefficients from twin studies, inbreeding depression scores, brain evoked potentials, brain pH levels, brain glucose metabolism, nerve conduction velocity, and reaction time measures.

    “He showed that a test's g loading is the best predictor, not just of that test's correlation with scholastic and work-place performance, but of biological measures such as heritability coefficients determined from twin studies, inbreeding depression scores calculated in children of cousin-marriages, brain evoked potentials, brain pH levels, brain glucose metabolism, as well as nerve conduction”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Jensen [22]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisecitation

    Hills and Stanley found that Black college students' scores on the School and College Ability Test were normally distributed and predicted college grades, but averaged at about the 50th percentile on 8th grade national norms.

    “They found that the scores were normally distributed and predicted college grades.However, the average for the Black college students on the SCAT was at about the 50th percentile on 8th grade national norms.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Hills and Stanley [31]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Interpretationreasoning

    Black-White IQ differences are more pronounced on the more g loaded and more heritable components of tests, which implies the differences are partly genetic in origin.

    “That Black-White IQ differences are more pronounced on the more g loaded and more heritable components of tests does indeed imply the differences are partly genetic in origin.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationcitation

    The 20% reduction in the Black-White achievement difference occurred by the 1980s and no longer continued, and was compatible with a heritability of 80% for IQ.

    “Even this 20% reduction (not the 35% claimed by Nisbett) had: (a) occurred by the 1980s and no longer continued; and (b) was compatible with a heritability of 80% for IQ.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Gottfredson [28]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites Gottfredson [29]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisecitation

    An IQ of 71 was found for Black children in an entire school district from a rural county in Georgia, while the White IQ in the same county was 101.

    “An IQ of 71 was found for the Black children in an entire school district from a rural county in Georgia in the U. S. Deep South; the White IQ in the same county was 101 [30].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [30]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisecitation

    Five independent data sets showed rising IQ scores but also an absence of measurement invariance, indicating that the test scores had different meanings for the different cohorts.

    “Five independent data sets showed rising IQ scores, but also an absence of measurement invariance, thereby indicating that the test scores had different meanings for the different cohorts.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Wicherts et al. [52]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Classified as probably not a substantial claim.

    Premisecitation

    Military testing during World War II was probably the most representative sampling of African American IQ ever undertaken.

    “As Murray noted, the military testing during World War II was probably the most representative sampling of African American IQ ever undertaken.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Murray

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Interpretationreasoning

    The problems raised by Wicherts and Johnson are beside the point because the empirical literature shows remarkable generalizability for both item characteristics and heritability estimates.

    “In our view, the problems raised by Wicherts and Johnson [64] are beside the point because the empirical literature shows there is, in fact, remarkable generalizability for both item characteristics and heritability estimates.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [64]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisecitation

    World War II military testing was more inclusive than World War I testing, which had excluded most of the 70% of African Americans who still lived in the rural South and were unschooled or very poorly schooled.

    “It was more inclusive than that conducted during World War I, which had excluded most of the 70% of African Americans who still lived in the rural South and were unschooled or very poorly schooled.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Murray

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductcitation

    The analyses were repeated in alternate ways and the results were found to be very similar.

    “The analyses were repeated in alternate ways and the results found to be very similar.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    The pattern of East Asians having faster decision times but Blacks having faster movement times eliminates the hypothesis that RT differences reflect a difference in motivation.

    “Moreover, although the East Asians averaged faster decision times than the Whites or the Blacks, the Blacks averaged faster movement times than the Whites or the East Asians, thereby eliminating the hypothesis that the differences on these tests reflect a difference in motivation.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationcitation

    The adopted children's g factor scores mainly reflected the SES level of their biological parents, implying that g is less amenable to environmental manipulation.

    “By contrast, the adopted children's g factor scores mainly reflected the SES level of their biological parents, which implied that g is less amenable to environmental manipulation.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Reaction times are measured on an absolute scale and indicate the neurophysiological efficiency of the brain's capacity to process information accurately, which is the same ability measured by intelligence tests.

    “Reaction times are measured on an absolute scale (i.e., one with a true zero) and indicate the neurophysiological efficiency of the brain's capacity to process information accurately, which is the same ability measured by intelligence tests [72][73][74].”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [72]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [73]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [74]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S1 (asserted).

    Interpretationreasoning

    If Black-specific X factors affect IQ, correlations between background variables and outcome measures for Blacks should be offset relative to other groups.

    “If Black-specific X factors are truly having an effect, some of these correlations for Blacks should be offset (up or down).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationcitation

    The overall mean for East Asians was 17 cm3 more than that for Whites and 97 cm3 more than that for Blacks.

    “Thus, the overall mean for East Asians was 17 cm 3 more than that for Whites and 97 cm 3 more than that for Blacks.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Paul Broca [125] found Blacks averaged lighter brains than Whites and had less complex convolutions and smaller frontal lobes.

    “When Paul Broca [125] measured brain weight at autopsy, he found Blacks averaged lighter brains than Whites and also had less complex convolutions and smaller frontal lobes.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [125]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisecitation

    Five independent studies have examined the within-family correlation between brain size and IQ, and only Schoenemann et al. failed to find the relationship.

    “Nisbett's citation of Schoenemann et al.'s [114] paper to support his claim of no within-family correlation between brain size and IQ is highly selective because five independent studies have now examined the within-family correlation between brain size and IQ [114,[119][120][121][122] and only Schoenemann et al. failed to find the relationship.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [114,[119][120][121][122]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisenone given

    The NASA data set contained only a single Black sample (454 African mine laborers from South Africa) with no variance and so no possibility of being statistically analyzed.

    “Nisbett was highly selective in citing a compilation of data by NASA as evidence that Black populations do not always average a smaller brain than Whites, for the NASA data set contained only a single Black sample (454 African mine laborers from South Africa) with no variance and so no possibility of being statistically analyzed.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    The correlation between indirect head size measures and IQ is about .20 and is reliable and significant.

    “This is much higher than the .20 found using indirect head size measures, though that correlation is also reliable and significant [116].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [116]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisecitation

    In African and non-African university students, scores on one IQ test correlated with scores on another IQ test 3 months earlier (.60 for Africans; .70 for non-Africans) and with end-of-year exam marks 3 months later (.34 for Africans; .28 for non-Africans).

    “In the Rushton et al. [40,41] studies of African and non-African university students, scores on one IQ test correlated with scores on another IQ test 3 months earlier (.60 for Africans; .70 for non-Africans) and with end-of-year-exam marks measured 3 months later (.34 for Africans; .28 for non-Africans).”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [40]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [41]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Interpretationreasoning

    The differences in brain size were not mere correlates of body size and unlikely due to nutrition, since Black children were tallest and heaviest, while East Asian children were shortest and lightest.

    “The differences in brain size were not mere correlates of body size, and unlikely to be due to nutrition, since the Black children were the tallest in stature and heaviest in weight, while the East Asian children were the shortest in stature and lightest in weight.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Rushton [23] averaged the data and found East Asians = 1,364 cm3, Whites = 1,347 cm3, and Blacks = 1,267 cm3, with a standard deviation of about 10%.

    “Rushton [23] averaged the data and found: East Asians = 1,364 in cm 3 ; Whites = 1,347; and Blacks = 1,267, with a standard deviation of about 10%.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [23]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Interpretationcitation

    The evidence has never supported the hypotheses that brain size differences are due to perinatal factors, prematurity, or poorer post-natal nutrition.

    “But the evidence has never supported these long standing and reasonable hypotheses.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S4 (based). May combine two claims.

    Interpretationnone given

    Larger brains are more intelligent because they contain more neurons and synapses and process information faster and more efficiently.

    “Larger brains are more intelligent because they contain more neurons and synapses and process information faster and more efficiently.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    On average, women excel in verbal ability, perceptual speed, and motor coordination within personal space, while men do better on spatial tests and mathematical reasoning.

    “According to Kimura [144], on average, women excel in verbal ability, perceptual speed, and motor coordination within personal space, while men do better on various spatial tests and on tests of mathematical reasoning.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [144]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisecitation

    The Minnesota Trans-Racial Adoption Study is the largest and best-known of these studies and the only one that included a longitudinal follow-up, with testing of the same children at ages 7 and 17.

    “We placed greatest weight on the Minnesota Trans-Racial Adoption Study because it is the largest and best-known of these studies and is the only one that included a longitudinal follow-up, with testing of the same children at ages 7 and 17 years [156,157].”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [156]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [157]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisenone given

    Behavior genetic studies demonstrate that as people age their genes exert ever more influence, whereas family socialization effects decrease.

    “As shown in Fig. (4), behavior genetic studies demonstrate that as people age their genes exert ever more influence, whereas family socialization effects decrease.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Joiner's sample was of 12- to 18-year-olds who had previously been analyzed by Rushton and Osborne [154], finding an age x sex x race interaction where girls matured earlier than boys and Blacks matured earlier than Whites, resulting in young Black girls being larger in body and head size than White counterparts.

    “He failed to mention that Joiner's sample was of 12-to 18-yearolds who had previously been analyzed by Rushton and Osborne [154] in a study of the heritability of cranial capacity in which an age x sex x race interaction found that girls matured earlier than boys and Blacks matured earlier than Whites, resulting in young Black girls being larger in body (and head) size than their White counterpart”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [154]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Interpretationreasoning

    Most of Nisbett's cited studies are weak and non-decisive and have not been replicated even once.

    “Most are weak and non-decisive and have not been replicated even once.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    In metaanalyses of general population samples on the Progressive Matrices, there is no sex difference in IQ among children aged 6-14, but a male advantage from 15 years through old age, equivalent to about 4.6 IQ points by adulthood.

    “Subsequently, in metaanalyses of general population samples on the Progressive Matrices, Lynn and Irwing [149,151,151] found no sex difference in IQ among children aged 6-to 14-years but a male advantage from 15-years through old age, with the male advantage by adulthood being equivalent to about 4.6 IQ points.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [149]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [151]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisecitation

    At any given body surface area or height, White men have heavier brains than White women, and Black men have heavier brains than Black women.

    “He re-examined Ho et al.'s [112] autopsy data on 1,261 American adults and found that at any given body surface area or height, the brains of White men are heavier than those of White women, and the brains of Black men are heavier than those of Black women.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [112]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisecitation

    At age 17, adopted White children had an average IQ of about 106; Mixed-Race adoptees, 99; and adopted Blacks, 89.

    “At age 17 adopted White children had an average IQ of about 106; Mixed-Race adoptees, 99; and adopted Blacks, 89.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [157]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisecitation

    The sex difference in brain size was found in all of 20 or more separate analyses and replicated across East Asians, Whites, and Blacks.

    “This difference was found in all of the 20 or more separate analyses (shown in Fig. 6) conducted to rule out any body size effect, and was replicated across samples of East Asians, Whites, and Blacks.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [137]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisecitation

    Among Whites 168-cm tall, the brain mass of men averaged about 100 grams heavier than that of women, whereas the uncorrected difference was 140 grams.

    “For example, among Whites 168-cm (5' 7”) tall (the approximate overall mean height for men and women combined), the brain mass of men averaged about 100 grams heavier than that of women, whereas the average difference in brain mass, uncorrected for body size, was 140 grams.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [112]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisecitation

    Nisbett is mistaken about the performance of the Ecuadorean GHRD sample; they perform at the same level as the rest of the community and similar to their relatives.

    “However, he is mistaken as to their performance relative to the rest of the community for they perform at the same level as the rest of the community and similar to their relatives [141].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [141]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisecitation

    Neither the social class of adopting parents nor the number of years in the adopted family had any effect on the child's IQ.

    “Neither the social class of the adopting parents, nor the number of years the child spent in the adopted family, had any effect on the child's IQ.”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [160]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [161]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [162]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Premisecitation

    Admixture mapping has greater statistical power than family-linkage studies and requires far fewer markers.

    “McKeigue [178] has shown how admixture mapping has greater statistical power than family-linkage studies, requiring far fewer markers.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites McKeigue [178]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Only the nonshared (or within-family) environmental variance in IQ remains relatively constant across the entire age range.

    “Note that only the nonshared (or within family) environmental variance remains relatively constant across the entire age range.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites McGue et al. [83]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisereasoning

    Larger brains require more time to grow and larger bodies to produce and sustain them.

    “They require more time to grow and larger bodies to produce and sustain them.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    The bigger an animal's brain, the longer it takes to reach sexual maturity and the fewer offspring it produces.

    “The bigger an animal's brain, the longer it takes to reach sexual maturity and the fewer offspring it produces.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Evolutionary selection pressures were different in the hot savanna where Africans evolved than in the cold northern regions Europeans experienced, or the even colder Arctic regions where East Asians evolved.

    “Evolutionary selection pressures were different in the hot savanna, where Africans evolved, than in the cold northern regions Europeans experienced, or the even colder Arctic regions where East Asians evolved.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Rushton [23]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S4 (based). May combine two claims.

    Interpretationreasoning

    Black children with parents of IQ 70 regress upward to their population average of 85, just as much as Black children with parents of IQ 115 regress downward.

    “Black children with parents of IQ 70 regress upwards to their population average of 85, just as much as do Black children with parents of IQ 115 regress downwards.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: IQ tests measure the same cognitive ability across racial and ethnic groups.
    • Rests on an assumption: The population average IQ is 85 for Blacks and 100 for Whites.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisereasoning

    Large brains would not have evolved unless they substantially contributed to evolutionary fitness.

    “From an adaptationist perspective, unless large brains substantially contributed to evolutionary fitness (defined as increased survival of genes through successive generations), they would not have evolved.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationcitation

    Ecological pressures selected for larger brains, slower rates of maturation, lower levels of sex hormone, and other life history characteristics in present-day East Asians and Europeans.

    “As these populations evolved into present-day East Asians and Europeans, the ecological pressures selected for larger brains, slower rates of maturation, and lower levels of sex hormone, and all the other life history characteristics [23].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Rushton [23]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The hominid brain has tripled in size over the last 3 million years from Australopithecus to Homo erectus to modern humans.

    “The hominid brain has tripled in size over the last 3 million years from Australopithecus to Homo erectus to modern humans [116,182,184].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [116]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [182]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [184]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Classified as probably not a substantial claim. May combine two claims.

    Premisecitation

    Homo sapiens arose in Africa about 150,000 years ago and then expanded northward beyond Africa about 100,000 years ago, with a European-East Asian split about 41,000 years ago.

    “This posits that Homo sapiens arose in Africa about 150,000 years ago and then expanded northward beyond Africa about 100,000 years ago, with a European-East Asian split about 41,000 years ago.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Rushton [23]

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S4 (based).

    Interpretationreasoning

    Black children's lower scores relative to White children are due to regression to a lower genetic mean.

    “The Black children are simply regressing to a lower genetic mean.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: IQ tests measure the same cognitive ability across racial and ethnic groups.
    • Rests on an assumption: Black children born to well-educated, affluent parents have test scores 2 to 4 points lower than White children born to poorly-educated, impoverished parents.

  • Classified as probably not a substantial claim. May combine two claims.

    Interpretationreasoning

    White children with parents of IQ 70 regress upward to their population average of 100, just as much as White children with parents of IQ 115 regress downward.

    “Similarly, White children with parents of IQ 70 regress upwards to their population average of 100, just as much as White children with parents of IQ 115 regress downwards.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: IQ tests measure the same cognitive ability across racial and ethnic groups.
    • Rests on an assumption: The population average IQ is 85 for Blacks and 100 for Whites.

  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given

    Parents pass on some, but not all, of their exceptional genes to their offspring.

    “This is because parents pass on some, but not all, of their exceptional genes to their offspring.”
    Quote in the paperNot a substantial claim
99 of 99

  • The paper relies on this without support.

    IQ tests measure intelligence, the general mental ability that the paper's conclusions about group differences in intelligence are about.

    “mean ethnic group differences in intelligence test scores”

  • The authors state this as an assumption.

    African university students score 1 SD (15 IQ points) above the mean of their population, as university students typically do.

    “Assuming that African university students score 1 SD (15 IQ points) above the mean of their population, as university students typically do, a median IQ of 84 is consistent with a general population mean of 70.”

  • The authors state this as an assumption.

    The most select African university students score two SDs above their group average, as they do at the best universities in the US.

    “Assuming such students score two SDs above their group average, as they do at the best universities in the US, this value too indicates an IQ of 70 for the general population.”

  • The paper relies on this without support.

    Language accounts for only about 7 IQ points out of the 30-point difference in test scores.

    “Even here, however, language accounts for only about 7 IQ points (out of the 30 point difference).”

  • The authors state this as an assumption.

    Intervention strategies such as the elimination of tapeworms, improved nutrition, and provision of electricity, schools, and hospitals will raise test scores in Africa.

    “More generally, we take it as non-arguable that intervention strategies such as the elimination of tapeworms, improved nutrition, and provision of electricity, schools, and hospitals will raise test scores in Africa, as indeed they will anywhere that such deleterious conditions are found.”

  • The paper relies on this without support.

    IQ tests measure the same cognitive ability across racial and ethnic groups.

    “both correlated with IQ scores about .90”

  • The paper relies on this without support.

    Skin color is a valid proxy for genetic admixture.

    “lighter-skinned African Americans average higher IQs than their darker-skinned counterparts”

  • The paper relies on this without support.

    The Black GIs in Eyferth's study were higher in IQ than average because U.S. Army selection rejected about 30% of Blacks versus 3% of Whites on the preinduction Army General Classification Test.

    “the Black GIs were almost certainly higher in IQ than average because at that time there was rigorous selection in the U.S. Army with a rejection rate for Blacks on the preinduction Army General Classification Test of about 30%, compared to 3% for Whites.”

  • The paper relies on this without support.

    Black children born to well-educated, affluent parents have test scores 2 to 4 points lower than White children born to poorly-educated, impoverished parents.

    “Regression helps to explain why Black children born to welleducated, affluent, parents have test scores 2 to 4 points lower than do White children born to poorly-educated, impoverished, parents.”

  • The paper relies on this without support.

    The population average IQ is 85 for Blacks and 100 for Whites.

    “Black children with parents of IQ 70 regress upwards to their population average of 85”
10 of 10

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • Classical admixture studies tend to suffer from small sample sizes, lack of replication, unrepresentative sampling, and young age at assessment.

    “In addition to uncertainty regarding the extent of admixture, these studies also tend to suffer from small sample sizes, lack of replication, distinctly unrepresentative sampling, and young age at assessment [28].”

    From Global Ancestry and Cognitive Ability (2019) · cites this paper as [28]

    Section 12 describes small groups in some admixture studies, including a comparison of 9 and 14 children. Section 12.2 criticizes assessment at young ages and notes selection issues in Eyferth’s study. The paper does not clearly establish that classical admixture studies generally lack replication or use distinctly unrepresentative samples, so those parts of the attributed claim go beyond the cited discussion. (LLM, conf=0.82)

    Experimental — accuracy not yet measured

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Summary reverses the within-family study's result

    Minor

    The earlier account says Schoenemann et al. was the only study that failed to find the brain-size/IQ relationship. The summary instead calls it the only study that failed to find an absence of that relationship, reversing the result.

  • An infant adoption study is called a late-adoption study

    Minor

    The passage characterizes three studies, including Winick et al., as involving late-adopted children, but its description of Winick et al. says the children were adopted as infants.

  • Table 3's r values are described as two different measures

    Minor

    The prose calls Table 3's values correlations between IQ and reaction time, but the table note identifies r as reliability.

  • Brain-size ranking reverses within one sentence

    Minor

    The passage says Black children had smaller cranial volumes than White children, then says White children had smaller cranial volumes than Black children at the same ages.

4 of 4

Cites

Flagged first, then by citations

Research works printed but not linked: 14

  1. Shuey AM. The testing of Negro intelligence 2nd ed. New York: Social Science Press 1966.
  2. Gottfredson LS. Implications of cognitive differences for schooling within diverse societies In: Frisby CL, Reynolds CR, Eds. Compre- hensive Handbook of Multicultural School Psychology. New York: Wiley 2005; pp. 517-54.
  3. Nichols PL. The effects of heredity and environment on intelli- gence test performance in 4-and 7-year-old white and Negro sibling pairs. Unpublished doctoral dissertation. University of Minnesota, Minneapolis 1972.
  4. Zindi F. Differences in performance. Psychologist 1994; 7: 549- 52.
  5. Flynn JR. Reply to Rushton: a gang of gs overpower factor analy- sis. Pers Individ Dif 1999; 26: 391-3.
  6. Lynn R, Meisenberg G. IQ in sub-Saharan Africa assessed from school assessments in math, science, and reading: some comments on Wicherts, Dolan, & van der Maas. Intelligence 2010; 38: 21-29.
  7. National Aeronautics and Space Administration. Anthropometric source book: Anthropometry for Designers (NASA Reference Pub- lication 1024). 1987; vol. 1.
  8. Ho KC, Roessmann U, Straumfjord JV, Monroe G. Analysis of brain weight: I & II. Arch Pathol Lab Med 1980; 104: 635-45.
  9. Broca P. Sur les crânes de la caverne de l'Homme Mort (Loere). Revue d'Anthropologie 1873; 2: 1-53.
  10. Simmons K. Cranial capacities by both plastic and water techniques with cranial linear measurements of the Reserve Collec- tion: White and Negro. Hum Biol 1942; 14: 473-98.
  11. Schultz AH. Comparison of White and Negro fetuses. In: Daven- port CB, Osborn HF, Wissler C, Laughlin HH, Eds. Scientific Papers of the Second International Congress of Eugenics: Vol. 2, Eugenics in Race and State (Plates 11 and 12). Baltimore, MD: Williams & Wilkins 1923.
  12. Joiner TE. Head size as an explanation of the race-measured IQ relation: negative evidence from child and adolescent samples. Sci Rev Ment Health Prac 2004; 3: 23-32.
  13. Broca P. Sur le volume et la forme du cerveau suivant les individus et suivant les races. Bulletin Société d'Anthropologie Paris 1861; 2: 139-207, 301-321, 441-446.
  14. Eyferth K. Leistungern verscheidener Gruppen von Besatzungskin- dern in Hamburg-Wechsler Intelligenztest für Kinder (HAWIK). Archiv für die gesamte Psychologie 1961; 113: 222-41.

Cited by

Sorted by citations

Related

Authors
Rushton, J. P., & Jensen, A. R.
Affiliations
Western University (CA)
Venue
The Open Psychology Journal
Publisher
Bentham Science Publishers Ltd.
Published
2010-01-19
Volume
3
Issue
1
Pages
9-35
ISSN
1874-3501 (ISSN-L)
DOI
10.2174/1874350101003010009
OpenAlex
W2135035123
Cited by
48
References
209
Citations by year
2026: 1 · 2025: 1 · 2024: 1 · 2023: 1 · 2022: 4 · 2021: 1 · 2020: 3 · 2019: 5 · 2018: 2 · 2017: 1 · 2016: 7 · 2015: 3 · 2014: 2 · 2013: 4 · 2012: 5
FWCI
6.26
Type
journal article
Language
en
Open access
Licence
Locations
The Open Psychology Journal (publishedVersion, cc-by)
Topics
  • Social Sciences › Psychology › Experimental and Cognitive Psychology › Cognitive Abilities and Testing
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Genetics › Race, Genetics, and Society
  • Social Sciences › Sociology and Political Science › Intergenerational and Educational Inequality Studies
Keywords
race and intelligence, heritability of intelligence, nature versus nurture, stereotype threat, caste, reaction time, brain size, racial mixing, regression to the mean, human origins, life-history traits

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Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-29.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-29.

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