THC Science

Spearman's hypothesis has two formulations. The original formulation was that the magnitudes of the black-white differences on tests of cognitive ability positively correlate with the tests' g-loading.^[1] The subsequent formulation was that the magnitude of the black-white difference on tests of cognitive ability is entirely or mainly a function of the extent to which a test measures general mental ability, or g.^[2]

Claims of validity of Spearman's hypothesis have been criticized on methodological grounds. Such claims have been used to support scientific racism.

Description

The hypothesis, first formalized by Arthur Jensen in the 1980s based on Charles Spearman's earlier comments on the topic, stated that the magnitude of the differences is directly related to the magnitude of the g-loadings of a test. Jensen devised the method of correlated vectors (MCV) to study this hypothesis and published his research in his paper, "The nature of the black–white difference on various psychometric tests: Spearman's hypothesis", a paper which elicited 29 comments from experts in the field.^[3] Jensen went on to argue that the finding of a positive correlation between group differences and g-loadings would support the hypothesis that the group differences were largely in general mental ability—the later formulation of Spearman's hypothesis.^[2]^[4] The validity of this inference has been much debated.

Related hypotheses

Group differences

Closely related to Spearman's hypothesis is the hypothesis that the magnitude of certain group differences correlates with within-group heritability estimates. Arthur Jensen and J. Phillippe Rushton, for example, reported in 2010 that the found psychometric meta-analytic correlation between g-loadings and heritability estimates was 1.^[5]

The international data, though, has challenged this finding: a study from Japan published in 2014 did find a correlation between g-loading and heritability, but only a third of that found by Jensen & Rushton;^[6] one from 2015 covering Korea that found no clear link between heritability and g-loadings of IQ subtests;^[7] and one from 2016 by Voronin, Te Nijenhuis, and Malykh found negative correlations between g-loadings and heritability in two samples of Russian twins.^[8]

Criticism

Spearman's hypothesis strongly implies natural differences in Black-White general intelligence. It has been used to justify pseudo-scientific racist theories.^[9]^[10]

Spearman's hypothesis and the arguments that invoke it have received multiple criticisms, including criticisms of Jensen's method of correlated vectors, of the inference that the first formulation of Spearman's hypothesis supports the second, and of genetic and biological arguments made on the basis of Spearman's hypothesis.

First, Jensen's MCV has been criticized with regards to the original formulation of Spearman's hypothesis. Peter Schönemann and others argue that MCV produces tautological results; Schönemann further notes that Jensen's summary of Spearman's hypothesis is vaguely-defined and essentially presents two contradictory interpretations.^[10] Dolan and Lubke (2001) find Schönemann's argument that the correlations are positive by mathematical necessity unconvincing; however, they agree with his broader concern about whether his correlations are a good test of the role of g in racial intelligence differences.^[11] Ashton and Lee (2005) argue that MCV can produce spurious results.^[12]

Second, Jensen's MCV has been criticized with regards to the claim that it supports the later formulation of Spearman's hypothesis. Dolan et al. (2004) argue that MCV lacks specificity: that is, that instances not including g differences could create a positive correlation between the magnitude of the group differences and the g-loadings. Dolan et al. (2004) note that they are specifically criticizing MCV as a way of proving that group differences largely or totally represent g differences; they don't argue against Spearman's hypothesis as originally formulated and they do not argue that the larger body of evidence does not support Spearman's hypothesis as later formulated. Hunt and Carlson summarize criticism:

The essence of these objections is that the method of correlated vectors does not consider alternative hypotheses concerning the latent traits that might give rise to the observed difference in test scores. When a more appropriate method of analysis, multigroup confirmatory factor analysis, is applied, it has been found that Spearman's hypothesis (i.e., that the difference is due to differences in general intelligence) is only one of several models that could give rise to the observed distributions in test scores (Dolan, 2000). These findings render the method of correlated vectors ambiguous—which is not the same as saying that the Jensen-Rushton position is incorrect. Our point is that the argument for the default hypothesis is an indirect one. It would be far better if a direct causal argument could be made linking racial/ethnic genetic differences to studies of the development of the brain.

However, Rushton and Jensen (2010) argued that this criticism misses the point because there was no absolute claim that g had been proven—only that the results were what would have been expected if a g difference did in fact exist.

Third, arguments based on Spearman's hypothesis have been criticized. Some have argued that culturally caused differences could produce a correlation between g-loadings and group differences. Flynn (2010) has criticized the basic assumption that confirmation of Spearman's hypothesis would support a partially genetic explanation for IQ differences. He argues that environmental causes for average group IQ differences would cause the differences to be greater for more complex tasks.^[13]

References

^ Jensen, A. R. (1985). The nature of the black–white difference on various psychometric tests: Spearman's hypothesis. Behavioral and Brain Sciences, 8(02), 193–219.
^ ^a ^b Hunt, E., & Carlson, J. (2007). Considerations relating to the study of group differences in intelligence. Perspectives on Psychological Science, 2(2), 194–213.
^ te Nijenhuis, J. (2012). Jan te Nijenhuis. The Flynn effect, group differences, and g loadings. Personality and Individual Differences.
^ Dolan, C. V., Roorda, W., & Wicherts, J. M. (2004). Two failures of Spearman's hypothesis: The GATB in Holland and the JAT in South Africa. Intelligence, 32(2), 155–173.
^ Rushton, J. P., & Jensen, A. R. (2010). "The rise and fall of the Flynn Effect as a reason to expect a narrowing of the Black–White IQ gap". Intelligence, 38(2), 213–219.
^ Te Nijenhuis, Jan; Kura, Kenya; Hur, Yoon-Mi (2014). "The correlation between g loadings and heritability in Japan: A meta-analysis". Intelligence. 46: 275–282. doi:10.1016/j.intell.2014.07.008.
^ Choi, Yu Yong; Cho, Sun Hee; Lee, Kun Ho (August 2015). "No Clear Link between G Loadings and Heritability: A Twin Study from Korea". Psychological Reports. 117 (1): 291–297. doi:10.2466/19.04.PR0.117c10z1. ISSN 0033-2941. PMID 26126212. S2CID 24209390.
^ Voronin, Ivan; Te Nijenhuis, Jan; Malykh, Sergey B. (November 2016). "THE CORRELATION BETWEEN g LOADINGS AND HERITABILITY IN RUSSIA". Journal of Biosocial Science. 48 (6): 833–843. doi:10.1017/S0021932015000395. ISSN 1469-7599. PMID 26507902. S2CID 2286258.
^ Fairchild, Harlford (1991). "Scientific Racism: The Cloak of Objectivity". Journal of Social Issues. 47 (3): 101–115. doi:10.1111/j.1540-4560.1991.tb01825.x.
^ ^a ^b Schönemann, Peter (1997). "Famous artefacts: Spearman's hypothesis" (PDF). Current Psychology of Cognition. 16 (6): 665–694.^{[dead link]}
^ Dolan, C.V. and Lubke, G.H. (2001). Viewing Spearman's hypothesis from the perspective of multigroup PCA: A comment on Schönemann's criticism. Intelligence 29, 231–245.
^ Ashton, M. C., & Lee, K. (2005). Problems with the method of correlated vectors. Intelligence, 33(4), 431–444.
^ Flynn, J. R. (2010). The spectacles through which I see the race and IQ debate. Intelligence, 38(4), 363–366.

[Jensen-1] Jensen, A. R. (1985). The nature of the black–white difference on various psychometric tests: Spearman's hypothesis. Behavioral and Brain Sciences, 8(02), 193–219.

[Hunt,_E._2007-2] Hunt, E., & Carlson, J. (2007). Considerations relating to the study of group differences in intelligence. Perspectives on Psychological Science, 2(2), 194–213.

[3] te Nijenhuis, J. (2012). Jan te Nijenhuis. The Flynn effect, group differences, and g loadings. Personality and Individual Differences.

[4] Dolan, C. V., Roorda, W., & Wicherts, J. M. (2004). Two failures of Spearman's hypothesis: The GATB in Holland and the JAT in South Africa. Intelligence, 32(2), 155–173.

[5] Rushton, J. P., & Jensen, A. R. (2010). "The rise and fall of the Flynn Effect as a reason to expect a narrowing of the Black–White IQ gap". Intelligence, 38(2), 213–219.

[6] Te Nijenhuis, Jan; Kura, Kenya; Hur, Yoon-Mi (2014). "The correlation between g loadings and heritability in Japan: A meta-analysis". Intelligence. 46: 275–282. doi:10.1016/j.intell.2014.07.008.

[7] Choi, Yu Yong; Cho, Sun Hee; Lee, Kun Ho (August 2015). "No Clear Link between G Loadings and Heritability: A Twin Study from Korea". Psychological Reports. 117 (1): 291–297. doi:10.2466/19.04.PR0.117c10z1. ISSN 0033-2941. PMID 26126212. S2CID 24209390.

[8] Voronin, Ivan; Te Nijenhuis, Jan; Malykh, Sergey B. (November 2016). "THE CORRELATION BETWEEN g LOADINGS AND HERITABILITY IN RUSSIA". Journal of Biosocial Science. 48 (6): 833–843. doi:10.1017/S0021932015000395. ISSN 1469-7599. PMID 26507902. S2CID 2286258.

[9] Fairchild, Harlford (1991). "Scientific Racism: The Cloak of Objectivity". Journal of Social Issues. 47 (3): 101–115. doi:10.1111/j.1540-4560.1991.tb01825.x.

[Schonemann-10] Schönemann, Peter (1997). "Famous artefacts: Spearman's hypothesis" (PDF). Current Psychology of Cognition. 16 (6): 665–694.^{[dead link]}

[11] Dolan, C.V. and Lubke, G.H. (2001). Viewing Spearman's hypothesis from the perspective of multigroup PCA: A comment on Schönemann's criticism. Intelligence 29, 231–245.

[12] Ashton, M. C., & Lee, K. (2005). Problems with the method of correlated vectors. Intelligence, 33(4), 431–444.

[13] Flynn, J. R. (2010). The spectacles through which I see the race and IQ debate. Intelligence, 38(4), 363–366.

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 '''Spearman's hypothesis''' has two formulations. The original formulation was that the magnitudes of the [[Race and intelligence#Test scores|black-white differences on tests of cognitive ability]] positively correlate with the tests' [[g factor (psychometrics)|g-loading]].<ref name="Jensen">Jensen, A. R. (1985). The nature of the black–white difference on various psychometric tests: Spearman's hypothesis. Behavioral and Brain Sciences, 8(02), 193–219.</ref> The subsequent formulation was that the magnitude of the black-white difference on tests of cognitive ability is entirely or mainly a function of the extent to which a test measures [[general mental ability]], or ''g''.<ref name="Hunt, E. 2007">Hunt, E., & Carlson, J. (2007). Considerations relating to the study of group differences in intelligence. Perspectives on Psychological Science, 2(2), 194–213.</ref>
+Claims of validity of Spearman's hypothesis have been criticized on methodological grounds. Such claims have been used to support [[scientific racism]].
 == Description ==
-The hypothesis, first formalized by [[Arthur Jensen]] in the 1980s based on [[Charles Spearman]]'s earlier comments on the topic, stated that the magnitude of the differences is directly related to the magnitude of the g-loadings of a test. Jensen devised the ''method of correlated vectors'' (MCV) to study this hypothesis and published his research in his paper, "The nature of the black–white difference on various psychometric tests: Spearman's hypothesis", a paper which elicited 29 comments from experts in the field. Some subsequent research has confirmed Jensen's original findings and has extended the hypothesis to other ethnic and racial groups.<ref>te Nijenhuis, J. (2012). Jan te Nijenhuis. The Flynn effect, group differences, and g loadings.  Personality and Individual Differences.</ref> In 2002, Jensen stated that he had now tested Spearman's hypothesis—the original formulation—on twenty-five large independent samples, and it had been confirmed on every one. Based on all these studies, he asserted, "the overall probability that Spearman's hypothesis is false is less than one in a billion."<ref>Miele, Frank (2002). Intelligence, Race and Genetics. Conversations with Arthur R. Jensen.  Westview Press. Paperback edition first published in 2004 by Westview Press. {{ISBN|0-8133-4274-0}} (pbk). Page 138.</ref>
+The hypothesis, first formalized by [[Arthur Jensen]] in the 1980s based on [[Charles Spearman]]'s earlier comments on the topic, stated that the magnitude of the differences is directly related to the magnitude of the g-loadings of a test. Jensen devised the ''method of correlated vectors'' (MCV) to study this hypothesis and published his research in his paper, "The nature of the black–white difference on various psychometric tests: Spearman's hypothesis", a paper which elicited 29 comments from experts in the field.<ref>te Nijenhuis, J. (2012). Jan te Nijenhuis. The Flynn effect, group differences, and g loadings.  Personality and Individual Differences.</ref> Jensen went on to argue that the finding of a positive correlation between group differences and g-loadings would support the hypothesis that the group differences were largely in general mental ability—the later formulation of Spearman's hypothesis.<ref name="Hunt, E. 2007" /><ref>Dolan, C. V., Roorda, W., & Wicherts, J. M. (2004). Two failures of Spearman's hypothesis: The GATB in Holland and the JAT in South Africa. Intelligence, 32(2), 155–173.</ref> The validity of this inference has been much debated.
-Jensen went on to argue that the finding of a positive correlation between group differences and g-loadings strongly supported the hypothesis that the group differences were largely in general mental ability—the later formulation of Spearman's hypothesis.<ref>Dolan, C. V., Roorda, W., & Wicherts, J. M. (2004). Two failures of Spearman's hypothesis: The GATB in Holland and the JAT in South Africa. Intelligence, 32(2), 155–173.</ref>  The validity of this inference has been much debated. Jensen and others provided alternative tests for the hypothesis that the group differences were largely in general mental ability.  These include a method devised by Robert Gordon which involves creating a group difference factor and then determining the congruence coefficient between the general intelligence factor and the group difference factor.<ref>Jensen, A. R. (1987). Further evidence for Spearman's hypothesis concerning black–white differences on psychometric tests. Behavioral and Brain Sciences, 10(03), 512–519.</ref>
-Later studies showed that Spearman's hypothesis is not confined to black-white differences, nor is it merely an American phenomenon. A positive correlation between score gap size and ''g'' loading has been observed in comparisons of European populations with [[Romani people|Roma]] communities,<ref>{{Cite journal|last1=Rushton|first1=J. Philippe|last2=Čvorović|first2=Jelena|last3=Bons|first3=Trudy Ann|date=2007|title=General mental ability in South Asians: Data from three Roma (Gypsy) communities in Serbia|journal=Intelligence|volume=35|issue=1|pages=1–12|doi=10.1016/j.intell.2006.09.002}}</ref> Central Asian populations,<ref>{{Cite journal|last1=te Nijenhuis|first1=Jan|last2=Grigoriev|first2=Andrei|last3=van den Hoek|first3=Michael|date=2016|title=Spearman's hypothesis tested in Kazakhstan on the items of the Standard Progressive Matrices Plus|journal=Intelligence|volume=92|pages=191–193|doi=10.1016/j.paid.2015.12.048}}</ref> Native Americans,<ref>{{Cite journal|last1=te Nijenhuis|first1=Jan|last2=van den Hoek|first2=Michael|last3=Armstrong|first3=Elijah L.|date=2015|title=Spearman's hypothesis and Amerindians: A meta-analysis|journal=Intelligence|volume=50|pages=87–92|doi=10.1016/j.intell.2015.02.006}}</ref> and Jews (from both United States and Israel).<ref>{{Cite journal|last1=te Nijenhuis|first1=Jan|last2=David|first2=Hanna|last3=Metzen|first3=Daniel|last4=Armstrong|first4=Elijah L.|date=May 2014|title=Spearman's hypothesis tested on European Jews vs non-Jewish Whites and vs Oriental Jews: Two meta-analyses|journal=Intelligence|volume=44|pages=15–18|doi=10.1016/j.intell.2014.02.002}}</ref> Spearman's hypothesis has also been observed in academic achievement tests, which indicates that it is not a unique characteristic of intelligence tests.<ref>{{Cite journal|last=Warne|first=Russell T.|date=2016|title=Testing Spearman's hypothesis with Advanced Placement examination data|journal=Intelligence|volume=57|pages=87–95|doi=10.1016/j.intell.2016.05.002}}</ref> Others have used Jensen's method of correlated vectors to test whether other group differences are related to a test's g-loading, such as differences between test-training groups and non-training groups, between Protestants and Catholics in Europe, between cohorts, and so on.<ref>te Nijenhuis, J., van Vianen, A. E., & van der Flier, H. (2007). Score gains on'' g''-loaded tests: No'' g''. Intelligence, 35(3), 283–300.</ref><ref>Steppan, M. (2010). Protestantism and intelligence: Max Weber and the Rindermann-paradox. The International Journal of Educational and Psychological Assessment, 5, 134–154.</ref>
 == Related hypotheses ==
 ===Group differences===
-Closely related to Spearman's hypothesis is the hypothesis that the magnitude of certain group differences correlates with within-group heritability estimates. [[Arthur Jensen]] and [[J. Phillippe Rushton]], for example, reported in 2010 that the found psychometric meta-analytic correlation between g-loadings and heritability estimates was 1.<ref>Rushton, J. P., & Jensen, A. R. (2010). "The rise and fall of the Flynn Effect as a reason to expect a narrowing of the Black–White IQ gap". ''Intelligence'', 38(2), 213–219.</ref> Their argument was supported by several US studies supporting this correlation, with the most cited adoption projects that sought to estimate the heritability of IQ were those of Texas,<ref name=Loehlin1989>{{cite journal | jstor = 1131039 | title = Modeling IQ Change: Evidence from the Texas Adoption Project | pmid = 2758892 | doi = 10.2307/1131039 | volume = 60 | number = 4 | year = 1989 | journal = Child Development | pages = 993–1004 | first1 = JC | last1 = Loehlin  | first2 = JM  | last2 = Horn  | first3 = L | last3 = Willerman  }}</ref> Colorado<ref>{{cite journal  | title = The Colorado Adoption Project  | pmc = 3817005  | pmid = 23158098  | doi = 10.1017/thg.2012.109  | volume = 16  | issue = 1  | year = 2013  | journal = Twin Res Hum Genet  | pages = 358–65  | last1 = Rhea  | first1 = SA  | last2 = Bricker  | first2 = JB  | last3 = Wadsworth  | first3 = SJ  | last4 = Corley
+Closely related to Spearman's hypothesis is the hypothesis that the magnitude of certain group differences correlates with within-group heritability estimates. [[Arthur Jensen]] and [[J. Phillippe Rushton]], for example, reported in 2010 that the found psychometric meta-analytic correlation between g-loadings and heritability estimates was 1.<ref>Rushton, J. P., & Jensen, A. R. (2010). "The rise and fall of the Flynn Effect as a reason to expect a narrowing of the Black–White IQ gap". ''Intelligence'', 38(2), 213–219.</ref>
- | first4 = RP }}</ref> and Minnesota<ref>{{cite journal | title = The Minnesota Adoption Studies: genetic differences and malleability | author = Scarr S and Weinberg RA  | pmid = 6872626  | volume = 54 | issue = 2  | journal = Child Dev | pages = 260–7 | doi = 10.2307/1129689 | jstor = 1129689  | year = 1983  }}</ref>
-that were started in the 1970s.
-The international data, though, has challenged this finding: a study from Japan published in 2014 did find a correlation between g-loading and heritability, but only a third of that found by Jensen & Rushton;<ref>{{Cite journal|url=https://doi.org/10.1016/j.intell.2014.07.008|doi = 10.1016/j.intell.2014.07.008|title = The correlation between g loadings and heritability in Japan: A meta-analysis|year = 2014|last1 = Te Nijenhuis|first1 = Jan|last2 = Kura|first2 = Kenya|last3 = Hur|first3 = Yoon-Mi|journal = Intelligence|volume = 46|pages = 275–282}}</ref> one from 2015 covering [[Korea]] that found no clear link between heritability and g-loadings of IQ subtests;<ref>{{Cite journal |last1=Choi |first1=Yu Yong |last2=Cho |first2=Sun Hee |last3=Lee |first3=Kun Ho |title=No Clear Link between G Loadings and Heritability: A Twin Study from Korea |date=August 2015 |journal=Psychological Reports |volume=117 |issue=1 |pages=291–297 |doi=10.2466/19.04.PR0.117c10z1 |issn=0033-2941 |pmid=26126212|s2cid=24209390 }}</ref> and one from 2016 by Voronin, [[Jan te Nijenhuis|Te Nijenhuis]], and Malykh found negative correlations between g-loadings and heritability in two samples of [[Russia]]n twins.<ref>{{Cite journal |last1=Voronin |first1=Ivan |last2=Te Nijenhuis |first2=Jan |last3=Malykh |first3=Sergey B. |date=November 2016 |title=THE CORRELATION BETWEEN g LOADINGS AND HERITABILITY IN RUSSIA  |journal=Journal of Biosocial Science |volume=48 |issue=6 |pages=833–843 |doi=10.1017/S0021932015000395 |issn=1469-7599 |pmid=26507902|s2cid=2286258 }}</ref>
-===Jensen effect===
-In 1998, Rushton proposed the term ''Jensen effect'' to refer to the positive and statistically significant correlation between the vector of many biological variables and that of the g-loadings of different subtests.<ref>{{Cite journal |last1=Woodley |first1=Michael A. |last2=Meisenberg |first2=Gerhard |title=A Jensen effect on dysgenic fertility: An analysis involving the National Longitudinal Survey of Youth |journal=[[Personality and Individual Differences]] |volume=55 |issue=3 |pages=279–282 |doi=10.1016/j.paid.2012.05.024|year=2013 }}</ref>
-== Implications ==
-This theory heavily implies that [[African Americans]] have less general cognitive ability than [[White Americans]]. See {{section link||Criticism}}.
-Jensen argued that Spearman's hypothesis explains why the black-white gap varies across different IQ tests. He also argued that were Spearman's hypothesis proven correct it would establish that the main source of the difference between whites and blacks on IQ tests is the same as the main source of the differences between individuals within each racial group, namely ''g''. If so, he argued, to understand the nature of the black-white gap, one would have to understand the nature of ''g''.<ref name=Jensen1998>Jensen, A.R. (1998). ''The ''g'' Factor: The Science of Mental Ability''. Westport, CT: Praeger. {{ISBN|0-275-96103-6}}, p. 371-383.</ref>
-Hereditarians, including Jensen, have also argued that Spearman's hypothesis (both formulations) supports their hereditarian position with regards to racial and ethnic differences.<ref name="Hunt, E. 2007"/> There are two arguments based on the two formulations of Spearman's hypothesis. The first is that a correlation between group differences and g-loadings is what one would expect if differences were predominantly genetically conditioned but not if differences were culturally conditioned.<ref>Gottfredson, L. S. (2005). What if the hereditarian hypothesis is true?. Psych. Pub. Pol. and L., 11, 311–605.</ref> The second is that g differences are deeply biologically and genetically rooted within populations and, as such, it's reasonable to postulate that they could be so rooted between populations.<ref>Gottfredson, L. S. (2007). Shattering logic to explain the Flynn effect. Cato Unbound.</ref> As for this latter point, Rushton and Jensen argued that a test's ''g''-loading also correlated with scholastic and workplace performance, heritability estimates determined from [[twin study|twin studies]], inbreeding depression scores calculated in children of cousin-marriages, brain [[evoked potential]]s, brain [[pH]] levels, brain [[glucose]] metabolism, as well as nerve conduction velocity, [[reaction time]], and other physiological factors. This, they argue, supports the view that ''g'' is biological and heritable. Therefore, a confirmation of Spearman's hypothesis and the similar relationship for heritability would support, they argued, the theory that the average racial IQ differences were partially genetic.<ref>{{Cite journal| last1 = Rushton| first1 = J. P.| last2 = Jensen| title = Thirty years of research on race differences in cognitive ability| journal = Psychology, Public Policy, and Law| volume = 11| issue = 2| pages = 235| year = 2005| doi = 10.1037/1076-8971.11.2.235| url = http://psychology.uwo.ca/faculty/rushtonpdfs/PPPL1.pdf| first2 = A. R.| url-status = dead| archive-url = https://web.archive.org/web/20120722020238/http://psychology.uwo.ca/faculty/rushtonpdfs/pppl1.pdf| archive-date = 2012-07-22| citeseerx = 10.1.1.186.102}}</ref>
+The international data, though, has challenged this finding: a study from Japan published in 2014 did find a correlation between g-loading and heritability, but only a third of that found by Jensen & Rushton;<ref>{{Cite journal|url=https://doi.org/10.1016/j.intell.2014.07.008|doi = 10.1016/j.intell.2014.07.008|title = The correlation between g loadings and heritability in Japan: A meta-analysis|year = 2014|last1 = Te Nijenhuis|first1 = Jan|last2 = Kura|first2 = Kenya|last3 = Hur|first3 = Yoon-Mi|journal = Intelligence|volume = 46|pages = 275–282}}</ref> one from 2015 covering [[Korea]] that found no clear link between heritability and g-loadings of IQ subtests;<ref>{{Cite journal |last1=Choi |first1=Yu Yong |last2=Cho |first2=Sun Hee |last3=Lee |first3=Kun Ho |title=No Clear Link between G Loadings and Heritability: A Twin Study from Korea |date=August 2015 |journal=Psychological Reports |volume=117 |issue=1 |pages=291–297 |doi=10.2466/19.04.PR0.117c10z1 |issn=0033-2941 |pmid=26126212|s2cid=24209390 }}</ref> and one from 2016 by Voronin, [[Jan te Nijenhuis|Te Nijenhuis]], and Malykh found negative correlations between g-loadings and heritability in two samples of [[Russia]]n twins.<ref>{{Cite journal |last1=Voronin |first1=Ivan |last2=Te Nijenhuis |first2=Jan |last3=Malykh |first3=Sergey B. |date=November 2016 |title=THE CORRELATION BETWEEN g LOADINGS AND HERITABILITY IN RUSSIA  |journal=Journal of Biosocial Science |volume=48 |issue=6 |pages=833–843 |doi=10.1017/S0021932015000395 |issn=1469-7599 |pmid=26507902|s2cid=2286258 }}</ref>
 == Criticism ==
-Spearman's hypothesis strongly implies natural differences in Black-White general intelligence. It has been used to justify [[scientific racism|pseudo-scientific racist theories]].<ref>{{Cite journal|last=Fairchild|first=Harlford|date=1991|title=Scientific Racism: The Cloak of Objectivity|journal=Journal of Social Issues|volume=47|issue=3|pages=101–115|doi=10.1111/j.1540-4560.1991.tb01825.x|url=https://doi.org/10.1111/j.1540-4560.1991.tb01825.x}}</ref>
+Spearman's hypothesis strongly implies natural differences in Black-White general intelligence. It has been used to justify [[scientific racism|pseudo-scientific racist theories]].<ref>{{Cite journal|last=Fairchild|first=Harlford|date=1991|title=Scientific Racism: The Cloak of Objectivity|journal=Journal of Social Issues|volume=47|issue=3|pages=101–115|doi=10.1111/j.1540-4560.1991.tb01825.x|url=https://doi.org/10.1111/j.1540-4560.1991.tb01825.x}}</ref><ref name=Schonemann />
 Spearman's hypothesis and the arguments that invoke it have received multiple criticisms, including criticisms of Jensen's method of correlated vectors, of the inference that the first formulation of Spearman's hypothesis supports the second, and of genetic and biological arguments made on the basis of Spearman's hypothesis.
-First, Jensen's MCV has been criticized with regards to the original formulation of Spearman's hypothesis. [[Peter Schönemann]] and others argue that MCV produces tautological results.<ref>{{Cite journal|last=Schönemann|first=Peter|date=1997|title=Famous artefacts: Spearman's hypothesis|url=https://d1wqtxts1xzle7.cloudfront.net/30745431/83.pdf?1362151267=&response-content-disposition=inline%3B+filename%3DFamous_artefacts_Spearmans_hypothesis.pdf&Expires=1592847978&Signature=cGB3qr-MZw3C72n24IUs16bBnPh5SM31RPRsrr3mbJD99JzeEBtsEuiupP2txDoa7eESsKoYSS842J2X9OI80Y46urH2HELzUICpmm6EZ1yqXSKJS49fSWdT8TAQoLX6Ssoc2mRIscI7iYINUOUd53~h-EOfBWjMrrpQE~qg5G7EMNx7WlvkXGqf7Sj4u0t~Z9EpAQg2kZX0Tima6ZJ08O1lFefemyoiOQ9aEi2Qy3e6fdLrZ9l2OtT1sS15~A8JskIdBAVFedcqOCh6lhfadHtMv3Tz5SRheJUADRGhuLbJcEQHJUncS1INRmA2Yh8IV3hJda~muZ8usSx694E1kA__&Key-Pair-Id=APKAJLOHF5GGSLRBV4ZA|journal=Current Psychology of Cognition|volume=16|issue=6|pages=665–694}}{{dead link|date=May 2021|bot=medic}}{{cbignore|bot=medic}}</ref> However, according to Dolan and Lubke (2001), Schönemann's analysis is incorrect; using simulations, they show that the correlations are not positive by mathematical necessity.<ref>Dolan, C.V. and Lubke, G.H. (2001). Viewing Spearman's hypothesis from the perspective of multigroup PCA: A comment on Schönemann's criticism. ''Intelligence 29'', 231–245.</ref>  Ashton and Lee (2005) argue that MCV can produce spurious results.<ref>Ashton, M. C., & Lee, K. (2005). Problems with the method of correlated vectors. Intelligence, 33(4), 431–444.</ref> However, according to te Nijenhuis et al. (2007), one can use psychometric meta-analysis to negate this problem.
+First, Jensen's MCV has been criticized with regards to the original formulation of Spearman's hypothesis. [[Peter Schönemann]] and others argue that MCV produces tautological results; Schönemann further notes that Jensen's summary of Spearman's hypothesis is vaguely-defined and essentially presents two contradictory interpretations.<ref name=Schonemann>{{Cite journal|last=Schönemann|first=Peter|date=1997|title=Famous artefacts: Spearman's hypothesis|url=https://d1wqtxts1xzle7.cloudfront.net/30745431/83.pdf?1362151267=&response-content-disposition=inline%3B+filename%3DFamous_artefacts_Spearmans_hypothesis.pdf&Expires=1592847978&Signature=cGB3qr-MZw3C72n24IUs16bBnPh5SM31RPRsrr3mbJD99JzeEBtsEuiupP2txDoa7eESsKoYSS842J2X9OI80Y46urH2HELzUICpmm6EZ1yqXSKJS49fSWdT8TAQoLX6Ssoc2mRIscI7iYINUOUd53~h-EOfBWjMrrpQE~qg5G7EMNx7WlvkXGqf7Sj4u0t~Z9EpAQg2kZX0Tima6ZJ08O1lFefemyoiOQ9aEi2Qy3e6fdLrZ9l2OtT1sS15~A8JskIdBAVFedcqOCh6lhfadHtMv3Tz5SRheJUADRGhuLbJcEQHJUncS1INRmA2Yh8IV3hJda~muZ8usSx694E1kA__&Key-Pair-Id=APKAJLOHF5GGSLRBV4ZA|journal=Current Psychology of Cognition|volume=16|issue=6|pages=665–694}}{{dead link|date=May 2021|bot=medic}}{{cbignore|bot=medic}}</ref> Dolan and Lubke (2001) find Schönemann's argument that the correlations are positive by mathematical necessity unconvincing; however, they agree with his broader concern about whether his correlations are a good test of the role of ''g'' in racial intelligence differences.<ref>Dolan, C.V. and Lubke, G.H. (2001). Viewing Spearman's hypothesis from the perspective of multigroup PCA: A comment on Schönemann's criticism. ''Intelligence 29'', 231–245.</ref>  Ashton and Lee (2005) argue that MCV can produce spurious results.<ref>Ashton, M. C., & Lee, K. (2005). Problems with the method of correlated vectors. Intelligence, 33(4), 431–444.</ref>
 Second, Jensen's MCV has been criticized with regards to the claim that it supports the later formulation of Spearman's hypothesis. Dolan et al. (2004) argue that MCV lacks specificity: that is, that instances not including ''g'' differences could create a positive correlation between the magnitude of the group differences and the ''g''-loadings. Dolan et al. (2004) note that they are specifically criticizing MCV as a way of proving that group differences largely or totally represent g differences; they don't argue against Spearman's hypothesis as originally formulated and they do not argue that the larger body of evidence does not support Spearman's hypothesis as later formulated.  Hunt and Carlson summarize criticism:
-{{quote|The essence of these objections is that the method of correlated vectors does not consider alternative hypotheses concerning the latent traits that might give rise to the observed difference in test scores. When a more appropriate method of analysis, multigroup confirmatory factor analysis, is applied, it has been found that Spearman's hypothesis (i.e., that the difference is due to differences in general intelligence) is only one of several models that could give rise to the observed distributions in test scores (Dolan, 2000). These findings render the method of correlated vectors ambiguous—which is not the same as saying that the Jensen-Rushton position is incorrect. Our point is that the argument for the default hypothesis is an indirect one. It would be far better if a direct causal argument could be made linking racial/ethnic genetic differences to studies of the development of the brain.}} However, Rushton and Jensen (2010) argued that this criticism misses the point because there was no absolute claim that ''g'' had been proven—only that the results were what would have been expected if a ''g'' difference did in fact exist. Moreover, te Nijenhuis et al. (2007) note that the method proposed by Dolan et al. (2004) is not without limitations:
+{{quote|The essence of these objections is that the method of correlated vectors does not consider alternative hypotheses concerning the latent traits that might give rise to the observed difference in test scores. When a more appropriate method of analysis, multigroup confirmatory factor analysis, is applied, it has been found that Spearman's hypothesis (i.e., that the difference is due to differences in general intelligence) is only one of several models that could give rise to the observed distributions in test scores (Dolan, 2000). These findings render the method of correlated vectors ambiguous—which is not the same as saying that the Jensen-Rushton position is incorrect. Our point is that the argument for the default hypothesis is an indirect one. It would be far better if a direct causal argument could be made linking racial/ethnic genetic differences to studies of the development of the brain.}} However, Rushton and Jensen (2010) argued that this criticism misses the point because there was no absolute claim that ''g'' had been proven—only that the results were what would have been expected if a ''g'' difference did in fact exist.
-{{quote|A principle of meta-analysis is that the amount of information contained in one individual study is quite modest. Therefore, one should carry out an analysis of all studies on one topic and correct for artifacts, leading to a strong increase of the amount of information. The fact that our meta-analytical value of r − 1.06 is virtually identical to the theoretically expected correlation between g and d of − 1.00 holds some promise that a psychometric meta-analysis of studies using MCV is a powerful way of reducing some of the limitations of MCV. An alternative methodological approach is to limit oneself to the rare datasets enabling the use of structural equations modeling. However, from a meta-analytical point of view, these studies yield only a quite modest amount of information.}}
 Third, arguments based on Spearman's hypothesis have been criticized. Some have argued that culturally caused differences could produce a correlation between g-loadings and group differences. Flynn (2010) has criticized the basic assumption that confirmation of Spearman's hypothesis would support a partially genetic explanation for IQ differences. He argues that environmental causes for average group IQ differences would cause the differences to be greater for more complex tasks.<ref>Flynn, J. R. (2010). The spectacles through which I see the race and IQ debate. Intelligence, 38(4), 363–366.</ref>
-Several recent studies of Spearman's hypothesis have been carried out using items instead of (sub)tests.<ref>{{Cite journal|last1=Te NijenhuiS|first1=Jan|last2=Batterjee|first2=Adel A.|last3=Van Den Hoek|first3=Michael|last4=Allik|first4=Jüri|last5=Sukhanovskiy|first5=Vladimir|title=Spearman's Hypothesis Tested Comparing Saudi Arabian Children and Adolescents with Various Other Groups of Children and Adolescents on the Items of the Standard Progressive Matrices|date=September 2017|journal=Journal of Biosocial Science|volume=49|issue=5|pages=634–647|doi=10.1017/S0021932016000535|pmid=27817753|s2cid=30785709|issn=0021-9320}}</ref> These studies find similar positive correlations as the ones using tests. This approach was first used by Rushton.<ref>{{Cite journal|last1=Rushton|first1=J. Philippe|last2=Bons|first2=Trudy Ann|last3=Vernon|first3=Philip A|last4=Čvorović|first4=Jelena|date=2007-07-22|title=Genetic and environmental contributions to population group differences on the Raven's Progressive Matrices estimated from twins reared together and apart|journal=Proceedings of the Royal Society B: Biological Sciences|volume=274|issue=1619|pages=1773–1777|doi=10.1098/rspb.2007.0461|issn=0962-8452|pmc=1914335|pmid=17504738}}</ref> This method variant has been criticized by [[Jelte Wicherts]] repeatedly because the item metrics from [[classical test theory]] are confounded by the ability level of the sample and this results in nonlinearities.<ref>{{Cite journal|last=Wicherts|first=Jelte M.|date=January 2017|title=Psychometric problems with the method of correlated vectors applied to item scores (including some nonsensical results)|journal=Intelligence|volume=60|pages=26–38|doi=10.1016/j.intell.2016.11.002|url=https://research.tilburguniversity.edu/en/publications/32f26f9f-9d0a-441d-a7f6-8c96b2669d25}}</ref><ref>{{Cite journal|last1=Wicherts|first1=Jelte M.|last2=Johnson|first2=Wendy|date=2009-07-22|title=Group differences in the heritability of items and test scores|journal=Proceedings of the Royal Society B: Biological Sciences|volume=276|issue=1667|pages=2675–2683|doi=10.1098/rspb.2009.0238|issn=0962-8452|pmc=2686655|pmid=19403538}}</ref>
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