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'''Race and intelligence''' can refer to issues raised in: |
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{{Dablink|This article also discusses issues regarding ethnicity and intelligence.}} |
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{{Expert-subject|Psychology|date=November 2008}} |
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{{Race}} |
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* Scholarly literature about the existence and causes of suspected [[Between-group differences in IQ|differences in intelligence across different genetic and social groups]]. |
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'''Race and intelligence''' is a controversial and even taboo topic, which has received considerable attention in the United States and elsewhere. At the heart of the issue is the observation that the members of racial and ethnic groups tend to cluster around different averages on [[intelligence quotient|tests of cognitive ability]]. Some scholars regard the topic as scientifically meaningless based on their interpretation of the meanings and significance of [[race]] and [[intelligence]].<ref name="Intelligence, Race, and Genetics">{{Cite doi|10.1037/0003-066X.60.1.46}}</ref> Some likewise question whether it is possible to scientifically address the question in a way that is ethical.<ref name="Cite doi|10.1038/457786a">{{Cite doi|10.1038/457786a}}</ref> Others reject both of these positions, arguing instead that the social implications are too important to forego research.<ref name="Cite doi|10.1038/457788a">{{Cite doi|10.1038/457788a}}</ref> |
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* The study of [[Heritability of IQ#Between-group heritability|genetic heritability of intelligence for individuals]]. |
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* Debates concerning the [[Race_(classification_of_human_beings)#Race_and_intelligence|meaning of Race]] in studies of intelligence. |
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* [[Intelligence_and_public_policy#Race_issues|Public policy issues]] affected by intelligence research. |
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It is generally agreed that there are significant differences in the average test scores of different population groups (with particular focus on self-identified [[African American|US Blacks]] and Whites).<ref name="Neisser 1996">Neisser, U., G. Boodoo, T. J. Bouchard, A. W. Boykin, N. Brody, S. J. Ceci, D. F. Halpern, J. C. Loehlin, R. Perloff, R. J. Sternberg and S. Urbina. 1996. "[[Intelligence: Knowns and Unknowns]]." ''American Psychologist'' 51:77-101.</ref> The distribution of test scores for each group are largely overlapping, but groups differ in where individuals tend to cluster along the test score continuum. For this reason, racial or ethnic identity does little to predict the IQ of any particular individual. Statistics for group differences, however, are well established in the United States, with black Americans performing poorly on average compared to whites; Americans of Chinese, Japanese and Jewish ancestry performing better on average than gentile whites; and Latino Americans performing intermediately to blacks and whites. It is also agreed that these test score differences are not simply a reflection of biased tests, and thus they they have important social implications, especially in the areas of academic and social achievement.<ref name="Neisser 1996"/> Yet the existence and importance of test score differences says nothing about their causes. |
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{{disambig}} |
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Although research and debate on race and intelligence encompasses a variety of topics, the [[nature versus nurture]] question attracts the most public attention. Some scholars argue that it is impossible for genetic differences to cause test score difference between racial and ethnic groups,<ref name="Intelligence, Race, and Genetics"/> but others reject this position, arguing that evidence is needed to decide the extent to which genetic factors contribute to group difference in IQ.<ref name="Nisbett 2009">{{cite book |title= Intelligence and How to Get It: Why Schools and Cultures Count |last= Nisbett |first= Richard |authorlink= Richard E. Nisbett |year= 2009|publisher= W. W. Norton & Company|location= New York, NY |isbn= 0393065057}}</ref> Public statements from several groups of psychologists indicate that no definitive answer exists on what causes test score differences between groups.<ref name="Neisser 1996"/><ref name="Mainstream Science on Intelligence">{{Cite doi | 10.1016/S0160-2896(97)90011-8}}</ref> Numerous interpretations have been proposed, but none are generally considered to be well-supported by research. While genetic factors are agreed to contribute to IQ differences among people of the same race, it is the subject of debate whether this also applies to differences in average IQ between groups.<ref name="Jensen 1998"/> Many psychologists believe that environmental factors could contribute, and many factors have been suggested as explanations, such as self-discipline and a culture that emphasizes engagement with learning<ref>Ogbu, J. (2002). Cultural amplifiers of intelligence: IQ and minority status in cross-cultural perspective. In J.M. Fish (Ed.), Race and intelligence: Separating science and myth (pp. 241–280). Mah-wah, NJ: Erlbaum.</ref><ref>Steinberg, R. (1996). Beyond the classroom: Why school reform has failed and what parents need to do. New York: Simon & Schuster.</ref>, but no specific environmental factor has been identified as a definitive cause.<ref name="Neisser 1996"/> These psychologists also consider the available evidence for a genetic contribution to group differences, which is based in part of studies of twins reared apart as well as adoption studies, to be inconclusive. Nonetheless, intense debate continues on that topic, with some scholars arguing that the available evidence favors an entirely environmental cause<ref name="Nisbett 2009"/> and others arguing that the evidence favors a contribution from both genes and environment<ref name="Jensen 1998"/>. |
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==Overview== |
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In 1995, a task force of the [[American Psychological Association]] (APA) headed by psychologist [[Ulric Neisser]] published a report entitled ''[[Intelligence: Knowns and Unknowns]]'' which intended to present a summary of the findings of scientific research regarding intelligence, which also commented upon the topic of racial-ethnic group differences in IQ.<ref name="Neisser 1996"/> According to this report, psychometric testing, although one of the most fruitful approaches to studying intelligence, has yet to produce answers to many questions regarding intelligence. [[Psychometrics|Psychometricians]] have devised ways to measure the distinct yet intercorrelated abilities believed to play an important role in the development of intelligence. IQ tests measure these abilities well. As intelligence test scores correlate moderately well with measures of educational and occupational success, it is apparent that such tests measure important skills. However, educational achievement is not only determined by intelligence, although intelligence test scores do correlate significantly with other important outcomes later in life. |
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The APA report further noted that, while both twin and adoption studies indicate that genetic and environmental variables are involved in the manifestation of intelligence, the role of genetics has been found to increase in importance with age. Why this happens in not yet understood, but while the influence of genetic factors increases with age the influence of family rearing environment fades away. Nonetheless, there are several important environmental factors which are known to affect the development of intelligence, such as formal education and general health. The much-discussed "[[Flynn effect]]", which refers to the striking worldwide mean IQ increase of 15+ points over the last 50 years, may be the result of similar environmental factors or some other hitherto unrecognized factor, and may not reflect a real increase in intelligence. |
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On the topic of racial-ethnic group differences in IQ, the APA task force wrote that, as the measured differences in IQ between various ethnic groups is the result of complex patterns, any conclusions which require broad generalizations run the risk of oversimplifying the issue as well as misrepresenting the available data. At the same time, intelligence test scores in some minority populations are reasonably good indicators of educational achievement levels in later life. The long-standing 15 +/- point difference between the intelligence test scores of African Americans and White Americans, though it might have shrunk during the 20th century, remains unaccounted for despite proposed explanations claiming [[systematic bias]], differences in culture or [[socioeconomic status]] (SES), or genetics as underlying causes. |
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===Suitability for study=== |
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Some scholars have expressed the view that the study of race differences in intelligence is meaningless, unethical or both. This is an on-going debate with proponents and opponents of this view making statements in the academic literature in support of their respective positions.<ref name="Cite doi|10.1038/457786a">{{Cite doi|10.1038/457786a}}</ref><ref name="Cite doi|10.1038/457788a">{{Cite doi|10.1038/457788a}}</ref> |
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For example, according to [[Robert Sternberg]] and colleagues<ref name="Intelligence, Race, and Genetics">{{Cite doi| 10.1037/0003-066X.60.1.46}}</ref>, intelligence (often approximated using IQ) is not a well defined construct, and IQ tests do not provide definitive measures of intelligence. They argue that race and ethnicity are socially defined groups—rather than biological observations—whose membership isn't homogeneous; races and ethnicities are often defined by affiliation with very large geographical areas (Asian) or common language (Hispanic). For these reasons, they conclude that discussions of correlations between race and intelligence which extrapolate a genetic causation are fundamentally flawed. |
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In another example, [[Richard E. Nisbett]]<ref name="Nisbett 2009"/>, who believes that the available evidence favors an entirely environmental explanation for differences in test scores between blacks and whites, nonetheless rejects the argument that studying these differences is meaningless and also rejects the argument that the research is unethical. Rather, Nisbett endorses the view that the cause of group differences can be resolved with empirical study. Similarly, [[James Flynn]]<ref name="Flynn 2007">{{Cite book | last = Flynn | first = James | authorlink = James Flynn | title = What Is Intelligence?: Beyond the Flynn Effect | publisher = Cambridge University Press | date = 2007 | location = New York, NY | isbn = 0521880076}}'</ref> argues that we should prioritize the search for truth above the supposed unwelcome consequences. Flynn cites the flow of new research stimulated by the work of [[Arthur Jensen]] in support of his view.<ref>{{Cite web| last = Flynn | first = James | title = Arthur Jensen and John Stuart Mill | url = http://www.cato-unbound.org/2007/11/23/james-r-flynn/arthur-jensen-and-john-stuart-mill/}}</ref> |
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==Test score differences== |
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{{further|[[Intelligence#Psychometric approach|Psychometric approach to measuring intelligence]]}} |
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Most of the evidence of intelligence differences between racial and ethnic groups is based on studies of [[IQ test|intelligence test]] scores. Intelligence tests measure many important abilities, such as verbal and quantitative reasoning, and can predict socially-relevant outcomes such as academic performance and occupational outcomes. However, intelligence test scores do not reflect all of the intricacies of the everyday meaning of intelligence, so researchers take care to distinguish between IQ test results and intelligence.<ref name="Intelligence, Race, and Genetics"/><ref name=AaaaiPage23>{{cite book |author=Lichtenberger, Elizabeth O.; Kaufman, Alan S |title=Assessing adolescent and adult intelligence |publisher=Allyn and Bacon |location=Boston |year=2002 |pages=23 |isbn=020530527x}}</ref> |
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Some studies of intelligence tests use statistical methods to extract so-called [[latent variable]]s from the IQ test scores. One such variable is the general intelligence factor, or ''g'', which accounts for most of the differences in IQ test scores between individuals. There are other latent variables in addition to ''g'', and IQ tests vary in their ability to measure these latent variables, if they measure them at all. IQ tests scores, while often summarized as a single overall number, are actually multidimensional in nature. Transforming IQ test scores into latent variables is an attempt to find one or dimensions on which to compare IQ test scores. |
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Latent variables are also sometimes called factors or constructs. The [[construct validity]] of an IQ test score is a key criteria for judging whether the IQ test score differences are meaningful. Tests which do not measure difference in important latent variables for some group are said to have measurement bias. The construct validity of most commonly used IQ tests has been fairly well established within multiple racial-ethnic groups in developing countries such as the United States. That is, test score difference within each racial-ethnic group are valid indicators of differences in latent variables such as ''g''. |
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The question of [[cultural bias]] in IQ tests is another facet of the construct validity question. One previously held view of IQ tests was that they only measure bits of information or skills that would be learned by children raised in a middle-class White culture. It would follow that lower-scoring ethnic-minority children would score lower simply because they lack exposure to the information and skills promoted by this culture. This view has since been discarded in favor of the view that IQ test score differences reflect real differences in mental abilities and that group differences in IQ are not a product of cultural bias. |
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There is a consensus that test score differences between Black and White people in the United States have [[predictive validity]] (also called predictive invariance), meaning that test scores predict the same socially-relevant outcomes regardless of the race of the person being tested. To further address this question, three studies using sophisticated statistical techniques have shown that Black-White differences in IQ test scores are not a result of measurement bias (a criteria called measurement invariance).<ref name="Dolan 2000">{{Cite doi|10.1207/S15327906MBR3501_2}}</ref><ref name="Dolan and Hamaker 2001">{{cite book | author = Dolan, C. V. and Hamaker, E. L. | authorlink = | coauthors = | year = 2001 | month = | title = Advances in Psychological Research | chapter = Investigating Black-White Differences in Psychometric IQ: Multi-Group Confirmatory Factor Analyses of the WISC-R and K-Abc, and a Critique of the Method of Correlated Vectors | editor = F. Columbus | others = | edition = | pages = | publisher = [[Nova Science Publishers]], Inc. | location = Huntington, NY | id = ISBN 1-56072-897-3 | url = http://users.fmg.uva.nl/cdolan/wch.pdf }}</ref><ref>Lubke, G. H., Dolan, C. V., Kelderman, H., & Mellenbergh, G. J. (2003). On the relationship between sources of within- and between-group differences and measurement invariance in the common factor model. Intelligence, 31, 543–566.</ref> These studies imply that Black-White IQ differences reflect very general differences in some underlying latent variables, but they are unable to differentiate precisely which latent variables differ under a variety of models. These studies were performed in response to previous investigations which suggested that Black-White IQ differences are primarily differences in ''g'' in particular.<ref name="Jensen 1998"/> |
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===United States=== |
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There are observed differences in average test score achievement between racial-ethnic groups, which vary depending on the populations studied and the type of tests used. Self defined black and white United States citizens have been the subjects of the greatest number of studies. Black-White average IQ differences appear to increase with age, reaching an average of nearly 17 points by age 24, which is slightly more than 1 standard deviation.<ref name = "IQ-gap">[http://www.cato-unbound.org/2007/11/20/james-r-flynn/the-black-white-iq-gap/ James R. Flynn, The Black-White IQ Gap]</ref> According to James Flynn and others, the overall average Black-White gap has reduced by one third over the course of the 20th century.<ref name = "IQ-gap"/> For example, the black men inducted into the US armed forces during World War II averaged about 1.5 standard deviations below their white counterparts.<ref>Loehlin, J. C., Lindzey, G., & Spuhler, J. N. (1975). Race differences in intelligence. San Francisco, CA: W.H. Freeman.</ref> This improvement is also reflected in Black-White differences on [[achievement gap|school achievement tests]], which have shrunk from about 1.2 to about 0.8 standard deviations. However, these improvements may have stalled for people born after the early 1970s.<ref>{{Cite doi|10.1016/j.intell.2006.07.004}}</ref> |
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The average black-white IQ difference also varies depending on test content. For example, two subsections of the [[Wechsler Intelligence Scale for Children|WISC]] IQ test, known as forward and reverse digit-span, ask children to repeat a long series of numbers either forwards or backwards. The black-white difference on forward digit span is relatively small, while the difference on reverse digit span is relatively large. Across a battery of tests, the size of the Black-White gap is correlated with the extent to which the tests measure the psychometric factor ''g'', which also accounts for most of the variation in interindividual differences in IQ test performance.<ref name="Jensen 1998">{{cite book | last = Jensen | first = Arthur | authorlink = Arthur Jensen | editor = | others = | title = The ''g'' Factor: The Science of Mental Ability | year = 1998 | publisher = Praeger Publishers | location = Westport, CT | id = ISBN 0-275-96103-6}}</ref> Gaps are seen in other tests of cognitive ability or aptitude, including university admission exams such as the [[SAT]] and [[Graduate Record Examination|GRE]] as well as employment tests for corporate settings and the military.<ref name="Roth 2001">{{Cite doi| 10.1111/j.1744-6570.2001.tb00094.x}}</ref> |
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The IQ distributions of other racial and ethnic groups in the United States are less well studied. Hispanic and Native American populations, including Arctic Natives,<ref name="Berry_1966">{{Cite doi|10.1080/00207596608247156}}</ref><ref name="MacArthur 1968">{{Cite doi|10.1080/00207596808246642}}</ref> tend to score worse on average than White populations but better on average than Black populations.<ref name="Roth 2001"/> East Asian populations may score higher on average than White populations in the United States as they do elsewhere.<ref name="Hunt and Carlson">Hunt, Earl & Carlson, Jerry. Considerations Relating to the Study of Group Differences in Intelligence. Perspectives on Psychological Science 2 (2), 194-213.</ref> A 1960 study of 1236 American teenagers calculated six IQ measures for Jews relative to white gentiles. The results found that the relative IQ of American Jews varied from a low of 91.3 (visual reasoning) to a high of 109.7 (Mathematics).<ref>Backman, M.E. (1972) Patterns of mental abilities: ethnic, socioeconomic and sex differences. American Educational Research Journal, 9,1-12.</ref> A recent review by Lynn (2004) used a 10 word vocabulary test to estimate the IQ of American Jews.<ref name="Lynn 2004">{{Cite doi | 10.1016/S0191-8869(03)00079-5}} </ref> The population of 150 Jews scored half a standard deviation above the 5300 white gentiles in verbal IQ.<ref name="Lynn 2004"/><ref name="Cochran 2005">{{Cite doi | 10.1017/S0021932005027069 }} [http://homepage.mac.com/harpend/.Public/AshkenaziIQ.jbiosocsci.pdf]</ref> |
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For each of these populations, there is some evidence that the mixture of ability factors that distinguish individuals are differentially distributed between groups. For example, East Asian populations tend to outscore White populations in performance IQ, whereas the test score differences skew towards higher verbal IQ for Ashkenazi-White differences. However, the mixture of abilities within groups appears to be nearly identical across many ethnic groups.<ref name="Carretta and Ree 1995">{{Cite doi | 10.1016/0191-8869(95)00031-Z}} </ref> The stability of these differences is also less well studied than Black-White differences. |
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===Worldwide=== |
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According to [[Richard Lynn]], [[J. Philippe Rushton]], and others, IQ test score differences are observed cross-culturally and around the world. Lynn has published three books summarizing IQ test scores from around the world.<ref>[[IQ and the Wealth of Nations]], [[Race Differences in Intelligence]], and [[IQ and Global Inequality]]</ref> The inaccuracy of the cross cultural IQ scores is well documented, but many scholars use the results as an estimate of worldwide IQ scores.<ref name = "Kanazawa">{{Cite doi| 10.1016/j.intell.2007.04.001}}</ref><ref name="Shatz">{{Cite doi|10.1016/j.intell.2007.03.002}}</ref><ref>{{Cite doi| 10.1016/j.intell.2007.03.004}}</ref><ref>{{Cite doi| 10.1016/j.intell.2007.02.002}}</ref> Lynn's meta-analysis lists [[East Asia]]ns (105), [[European ethnic groups|Europeans]] (99), [[Inuit]] (91), [[Southeast Asia]]ns and [[Indigenous peoples of the Americas|Amerindians]] (87 each), [[Pacific Islands|Pacific Islanders]] (85), South Asians/North Africans (84), Non-Bushmen [[sub-Saharan Africa]]ns (67), [[Indigenous Australians|Australian Aborigines]] (62) and [[Bushmen]] (54).<ref name="The Bell Curve">{{cite book | last = Hernstein | first = Richard J. | authorlink = | coauthors = Charles Murray | year = 1994 | title = The Bell Curve: Intelligence and Class Structure in American Life | publisher = Free Press | location = New York | id = ISBN 0-02-914673-9}}</ref><ref name="Lynn 1991">{{cite journal | author = Lynn, R. | year = 1991 | month = | title = Race Differences in Intelligence: A Global Perspective | journal = Mankind Quarterly | volume = 31 | issue = | pages = 255-296 | id = | url = http://www.mugu.com/cgi-bin/Upstream/People/Lynn/lynn-race-iq.html}}</ref><ref name="Lynn 2006">{{cite book | author = Lynn, R. | year = 2006 | month = In press| title = Race Differences in Intelligence: An Evolutionary Analysis| chapter = | editor = | others = | edition = | pages = | publisher = Washington Summit Books| location = | isbd = 1593680201] | url = }}</ref><ref name="Rushton-review">{{Cite doi | 10.1016/j.paid.2005.10.004}}</ref><ref name="main">Lynn, R. and Vanhanen, T. (2002). IQ and the wealth of nations. Westport, CT: Praeger. ISBN 0-275-97510-X</ref> International achievement test scores, including [[TIMSS]] and [[PISA]], have also been used to estimate average IQ worldwide with similar results where data is available.<ref>Rindermann, H. (2006). What do international student assessments measure?. Psychologische Rundschau, 57, 69–86.</ref><ref>{{Cite doi |10.1016/j.intell.2007.09.003}}</ref><ref>{{Cite doi| 10.1016/j.intell.2006.06.001}}</ref> |
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The very low IQ scores reported for sub-Saharan African populations are especially controversial. For example, Wicherts argues that the average IQ of sub-Saharan Africans is poorly measured by studies summarized by Lynn and is more likely 82.<ref>{{Cite doi|10.1016/j.intell.2009.05.002}}</ref> Lynn argues that representative samples instead yield an average of 68.<ref>{{Cite doi|10.1016/j.intell.2009.09.009}}</ref> According to anthropologist Mark Cohen, the frequently reported African mean IQ of 70 is "preposterous". Using Western standards, this would mean that African countries evidencing such a low IQ would be largely dysfunctional. Given that individuals in these countries lead "vibrant artistic, symbolic and spiritual lives", this is, according to Cohen, clearly not the case. Thus, he concludes, the IQ test results from Africa do not reflect actual intelligence levels.<ref>{{Cite journal | last = Cohen | first = Mark N. year = 2005| url = http://www.epjournal.net/filestore/ep03255262.pdf | title = Race and IQ Again: A Review of ''Race: The Reality of Human Differences'' by Vincent Sarich and Frank Miele | journal = Evolutionary Psychology | volume = 3 | pages = 255-262.}}</ref> |
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Differences in education, prolonged malnutrition, exposure to toxin, exposure to stress, and exposure to disease are all generally expected to contribute to the lower scores observed in developing countries. However, direct experimental evidence to confirm the role of individual factors is difficult to acquire in most cases because each of these factors tends to also be associated with one another and with unfavorable socioeconomic conditions.<ref name="Neisser 1996"/> In the case of some toxins, such as lead, a negative effect on IQ scores has been established. Two other factors that have as well established negative association with IQ are severely premature birth and severe low birth weight.<ref name="Neisser 1996"/> |
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==Hypotheses== |
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The cause(s) of group average IQ test score differences are not known but [[hypotheses]] have been proposed. Many scholars have offered descriptions of the variety of hypotheses that have been proposed. These descriptions usually distinguish between those hypotheses which invoke a major contribution of genetic factors (hereditarian) and those which invoke mainly environmental (i.e., non-genetic) factors. Some descriptions of the positions are themselves controversial. |
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In a review published in 2007, Hunt and Carlson categorized four explanations for observed differences in IQ scores between groups.<ref name="autogenerated1">[http://dx.doi.org/10.1111/j.1745-6916.2007.00037.x Considerations Relating to the Study of Group Differences in Intelligence]. Blackwell Synergy - Perspect on Psych Science, Volume 2 Issue 2 Page 194-213, June 2007 (Article Abstract)</ref> The strongest hereditarian position, attributed to Jensen and Rushton, is that group differences in IQ reflect differences in intelligence that are "due in substantial part to genetically determined differences in brain structure and/or function"<ref name="autogenerated1" /> A second position, attributed to Ogbu and Sowell, is that the differences in intelligence test scores are due to social factors. Third, Sternberg and colleagues are attributed with the view that the use of IQ scores to argue for differences in intelligence is an inappropriate use of tests in different groups. The fourth position, attributed to Fish and others, is that there is no such thing as race: "a term motivated by social concerns and not a scientific concept".<ref name="autogenerated1" /> |
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===Socioeconomic factors=== |
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[[Image:TBC-BW-IQ-SES-withDiff.png|left|thumb|250px|[[Socioeconomic status]] (SES) varies both between and within populations, but Black-White differences in IQ persist among the children of parents matched for SES, and the gap is largest among the children of wealthiest and best educated parents.<ref>Reviewed in Neisser et al. (1996). Data from the [[National Longitudinal Surveys|NLSY]] as reported in figure adapted from Herrnstein and Murray (1994), p. 288.</ref>]] |
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According to the report of a 1996 APA task force, socioeconomic factors (SES) cannot be the whole explanation for racial-ethnic group differences in IQ. Their first reason for this conclusion is that that the black-white test score gap is not eliminated when individuals and groups are matched on SES. Second, excluding extreme conditions, nutritional and biological factors that may vary with SES have little effect on IQ. Third, the relationship between IQ and SES is not simply one in which SES determines IQ, rather it is more likely that intelligence causes differences in SES than the other way around. Lastly, they argue that income and education simply fail to capture important categories of cultural experience which differ between racial and ethnic groups. |
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===Stereotype threat=== |
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{{Main|Stereotype threat}} |
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[[Stereotype]] threat is the fear that one's behavior will confirm an existing stereotype of a group with which one identifies; this fear may in turn lead to an impairment of performance.<ref>Aronson, Wilson, & Akert, 2005</ref> Testing situations that highlight the fact that intelligence is being measured tend to lower the scores of individuals from racial-ethnic groups that already score lower on average. Stereotype threat conditions cause larger than expected IQ differences among groups but do not explain the gaps found in non-threatening test conditions. |
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===The Flynn effect=== |
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{{Main|Flynn effect}} |
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The secular, international increase in test scores, commonly called the [[Flynn effect]], is seen by Flynn and others as reason to expect the eventual convergence of average black and white IQ scores. Flynn argues that the average IQ scores in several countries have increased about 3 points per decade during the 20th century, which he and others attribute predominantly to environmental causes.<ref>Flynn 1987, Flynn 1987b, Flynn 1999, Flynn 1999b</ref> This means, given the same test, the mean performance of [[African Americans]] today could be higher than the mean for [[white American]]s in 1920, though the gains causing this appear to have occurred predominantly in the lower half of the IQ distribution.<ref>Colom et al. 2005</ref> If an unknown environmental factor can cause changes in IQ over time, they argue, then contemporary differences between groups could also be due to an unknown environmental factor. |
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Nichols (1987)<ref>Nichols, R. C. (1987). Interchange: Nichols replies to Flynn. In S. Modgil & C. Modgil (Eds.), Arthur Jensen: Consensus and controversy (pp. 233–234). New York, NY: Falmer.</ref> critically summarized the argument as follows: |
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<blockquote> |
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(1) We do not know what causes the test score changes over time. |
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(2) We do not know what causes racial differences in intelligence. |
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(3) Since both causes are unknown, they must, therefore, be the same. |
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(4) Since the unknown cause of changes over time cannot be shown to be genetic, it must be environmental. |
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(5) Therefore, racial differences in intelligence are environmental in origin (p. 234). |
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</blockquote> |
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Flynn and other research have found reason to doubt the construct validity of secular increases in IQ scores.<ref>Flynn 1999</ref> In terms of the latent variables that IQ tests were designed to measure, such as ''g'' and verbal and mathematical ability, changes in IQ scores over time are different than either within-group individual differences and between group differences.<ref>Flynn (2007)</ref> For example, there has been little increase over time in performance on either the forward digit-span or reverse digit-span subtests, and tests of school achievement have been less affected than tests of abstract reasoning.<ref>James Robert Flynn (2007) ''What is Intelligence?: Beyond the Flynn Effect''. Cambridge University Press: Cambridge</ref> At least one study has found that measurement bias contributes to the Flynn effect, which is not seen in black-white IQ differences.<ref>Wicherts et al. (2004) found that measurement bias contributes to the Flynn effect. They wrote that "the gains cannot be explained solely by increases at the level of the latent variables (common factors), which IQ tests purport to measure." and "It appears therefore that the nature of the Flynn effect is qualitatively different from the nature of [black-white] differences in the United States" (p. 531).</ref> |
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===Heritability=== |
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[[Image:Heritability plants.jpeg|thumb|250px|An environmental factor that varies between groups but not within groups can cause group differences in a trait that is otherwise 100%[[Heritability|heritable]]. The height of this "ordinary genetically varied corn" is 100% heritable, but the difference between the groups is totally environmental. This is because the nutrient solution varies between populations, but not within populations.<ref>[http://www.nyu.edu/gsas/dept/philo/faculty/block/papers/Heritability.html How Heritability Misleads about Race]</ref>]] |
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{{See also|Heritability of IQ|Heritability|Genetic variation|Gene–environment interaction}} |
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There is a consensus among intelligence researchers that IQ differences between individuals within the same population (usually self identified "Black" or "White" in studies) are significantly heritable. It should be noted that heritability is a property of a population and may vary significantly between populations.<ref name="Neisser, U. 1996">Neisser, U., G. Boodoo, T. J. Bouchard, A. W. Boykin, N. Brody, S. J. Ceci, D. F. Halpern, J. C. Loehlin, R. Perloff, R. J. Sternberg and S. Urbina. 1996. "Intelligence: knowns and unknowns." ''American Psychologist'' 51:77-101.</ref><ref>R. J. Sternberg (2000) Handbook of Intelligence. Cambridge: Cambridge University Press</ref><ref>David J. Bartholomew (2004) Measuring Intelligence: Facts and Fallacies. Cambridge: Cambridge University Press</ref><ref>Ian J. Deary. (2001) Intelligence: A Very Short Introduction. Oxford: Oxford University Press</ref><ref>Gottfredson, L. S. (Ed.). (1997). Intelligence and social policy [Special issue]. Intelligence, 24(1).</ref><ref> Gottfredson, L. S. (1997). Mainstream science on intelligence: An editorial with 52 signatories, history, and bibliography. Intelligence, 24(1), 13-23.</ref><ref>Robert Plomin, John C. DeFries, Gerald E. McClearn, and Peter McGuffin (2000) Behavioral Genetics. Worth Publishers; Fourth Edition edition</ref><ref>Brody, N. (1992). Intelligence (2nd ed.). San Diego, CA: Academic Press.</ref><ref>Snyderman, M., & Rothman, S. (1988). The IQ controversy, the media and public policy. New Brunswick, NJ: Transaction Press.</ref> |
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[[Concordance (genetics)|Concordance rates]] for IQ from twin studies and other study designs consistently fall in the range of 30% to 80%, with the estimated [[heritability]] in young (preschool) children in the lower range and adults in the higher range.<ref>"Genetic foundations of human intelligence", Ian J. Deary, W. Johnson, L. M. Houlihan ''Hum Genet'' (2009)'''126''':215–232 {{DOI|10.1007/s00439-009-0655-4}}</ref> |
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Much of the research on explaining group differences stems from an observation promoted first by Arthur Jensen and later James Flynn and others regarding an environmental explanation for group differences. According to Jensen<ref>Jensen (1998) The g Factor</ref> the very high within-group[[heritability]] of IQ (within both white and black populations) presents a problem for environmental explanations of group differences in IQ. They consider two general classes of environmental factors: common environmental factors and X-factors. Common environmental factors vary within and between populations. X-factors vary between populations, but do not vary substantially within populations. They first consider common environmental factors. To account for a 1 SD B-W IQ gap only in terms of common environmental factors would require very large environmental differences. For example, if the within-group heritability of IQ is 80%, then a B-W IQ difference of 2.24 SD in common environmental factors is required. For a heritability of 40%, a difference of 1.29 SD is required. Jensen and Flynn agree that it is an empirical question whether common environmental factors that influence IQ differ between whites and blacks to such an extent, and both agree that most commonly suggested environmental factors do not. Jensen believes that empirical evidence supports the view that the B-W IQ gap is caused by both common environmental factors and genetic factors. Flynn disagrees and believes that empirical evidence supports the view that the B-W IQ gap is caused by yet unrecognized environmental factors.<ref>Flynn (1980) and Flynn (1999)</ref> |
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The alternative to common environmental factors is to hypothesize that X-factors account for the B-W IQ gap. A frequently-cited example from Lewontin describes the effect of a hypothetical X-factor. Imagine that the height of "ordinary genetically varied corn" is 100% heritable when grown in a uniform environment. Further imagine that two populations of corn are grown: one in a normal nutrient environment and the other in a deficient nutrient environment. Consequently, the average height of the corn grown in the deficient nutrient environment is less than the average height of the corn grown in the normal environment. In such a scenario, the within-group heritability of height is 100% in both populations, but the substantial difference between groups are due entirely to environmental factors. The quality of the nutrient is an "X-factor" in the language of Jensen and Flynn. With respect to the B-W IQ gap, Jensen suggests that effects associated with racism (both overt and [[institutionalized racism]]) might be X-factors. Flynn believes that attributing the B-W gap to the effects of racism is incorrect, because the most plausible ways in which discrimination could affect IQ are themselves common environmental factors. These may include psychological effects such as [[stereotype threat]]; biological effects such as poor nutrition, health care and living close to toxic environments; and educational effects such as a lack of good schools. Instead, Flynn and his colleague William Dickens have developed more complicated models to explain the black-white gap in terms of environmental factors. One initial motivation of the Dickens-Flynn theory was Flynn's observation that IQ test scores have been rising over time in countries around the world – termed the [[Flynn effect]]. Flynn and others believe an explanation for the Flynn effect may elucidate the cause of the B-W gap. Jensen and others disagree. |
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Critics have also questioned the interpretation of heritability as a whole. Lewontin suggests that some genotypes are more influenced by environments than others, leading to the possibility that populations that have similar genetic variance in the same environment can have different heritabilities because of their different genotypes.<ref name="lewontin70">Lewontin, R. (1970) "Race and Intelligence". ''Science and Public Affairs'' March, pp. 2-8</ref> David Layzer (1974) contends that the development of a trait can be influenced by genetic differences[[qualitative]]ly and that heritability estimates cannot measure such qualitative differences, as such it is possible that even with a heritability of close to 100% it is possibly for[[phenotypic]] variance to be due largely to environment.<ref name="layzer">Layzer, David. (1974) "Heritability analyses of IQ scores: Science or numerology?" ''Science'' '''183''' pp. 1259-66</ref> As a comparison, schizophrenia is estimated to be at least 70% heritable, of which 30% of the actual genes have been accounted for.<ref>[http://www.nimh.nih.gov/science-news/2009/schizophrenia-and-bipolar-disorder-share-genetic-roots.shtml Schizophrenia and Bipolar Disorder Share Genetic Roots]</ref><ref>Jianxin S, et al. Common variants on chromosome 6p22.1 are associated with schizophrenia. July 1, 2009, Nature</ref><ref>Stefansson H, et al. Common variants conferring risk of schizophrenia. July 1, 2009, Nature</ref><ref>Purcell SM, et al. Common polygenic variation contributes to risk of schizophrenia that overlaps with bipolar disorder. July 1, 2009, Nature</ref> |
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===Black and biracial children raised by white parents=== |
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Studies in which white parents raise black and biracial children have been variously regarded as inconclusive, supportive of an environmental interpretation, or supportive of a hereditarian interpretation. Three studies are commonly cited: the Minnesota Transracial Adoption Study<ref>Waldman, Weinberg, & Scarr, 1994</ref><ref>Weinberg, Scarr, & Waldman, 1992</ref>, Moore (1986), and Eyferth (1961). The Moore and Eyferth studies have been criticized due to concern that children and parents in these studies are not representative for reasons such as their age and circumstances that led their inclusion in the studies.<ref>Flynn 1980</ref> A similar study on black, white, and mixed-race children raised in an educationally-enriched nursery groups<ref>Tizard, Barbara; Cooperman, Oliver; Joseph, Anne; Tizard, Jack. (1972).[http://psycnet.apa.org/?fa=main.doiLanding&uid=1972-31260-001 Environmental effects on language development: A study of young children in long-stay residential nurseries].</ref> is cited by Nisbett; the study found IQs at age 5 of 108 for black children, 103 for white, and 106 for mixed-race.<ref name=NisbettHowToGetIt>Nisbett 2009 ''Intelligence and how to get it: Why schools and cultures count''</ref>{{Rp|224-5}} Like Moore (1986), the IQ of the parents is unknown, and the results could be distorted by the selective migration of the West Indian parents of the black children.<ref name=NisbettHowToGetIt/> |
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{| class="wikitable" border="1" |
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|- |
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! Biological parents |
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! Number of children |
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! Initial testing |
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! 10-year follow-up |
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|- |
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| colspan="4" | Minnesota Transracial Adoption Study initially tested at age 7 |
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|- |
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| Black-black |
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| 21 |
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| 91.4 |
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| 83.7 |
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|- |
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| Black-white |
|||
| 55 |
|||
| 105.4 |
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| 93.2 |
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|- |
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| White-white |
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| 16 |
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| 111.5 |
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| 101.5 |
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|- |
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| Biological children |
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| 101 |
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| 110.5 |
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| 105.5 |
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|- |
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| colspan="4" | Moore (1986) initially tested at age 7-10 |
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|- |
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| Black-black |
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| 9 |
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| 108.7 |
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| not done |
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|- |
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| Black-white |
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| 14 |
|||
| 107.2 |
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| not done |
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|- |
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| colspan="4" | Eyferth (1961) initially tested at age 5-13 |
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|- |
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| Black-white |
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| 171 |
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| 96.5 |
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| not done |
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|- |
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| White-white |
|||
| 70 |
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| 97.2 |
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| not done |
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|} |
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===African ancestry and IQ=== |
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African Americans typically have ancestors from both Africa and Europe, with on average 20% their genomes inherited from European ancestors. Several studies performed without the use of DNA-based ancestry estimation attempted to correlated estimates of African or European ancestry with IQ. These studies have been variously regarded as inconclusive, supportive of an environmental interpretation, or supportive of a hereditarian interpretation. These studies are generally criticized for using unreliable methods to estimate ancestry and for their small samples sizes. |
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Rowe (2005) and others have suggested using DNA-based methods to reproduce these studies with reliable estimates of ancestry. Such experiments have never been published, although the requirements for such a study have been discussed in the academic literature. |
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===Molecular genetic studies=== |
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The decoding of the [[human genome]] has enabled scientists to search for sections of the genome that contribute to cognitive abilities. Current studies using [[Quantitative trait loci]] have yielded little success in the search for genes influencing intelligence. [[Robert Plomin]] is confident that QTLs responsible for the variation in IQ scores exist, but that more powerful tools of analysis will be required to detect them.<ref>{{cite journal|title=The quest for quantitative trait loci associated with intelligence|doi=10.1016/j.intell.2006.01.001|last=Plomin|authorlink=Robert Plomin|year=2005|journal=Intelligence|volume=34|pages=513}}</ref> Some researchers have expressed reluctance to investigate possible links between genes and intelligence, due to the controversy it can produce.<ref>Antonio Regalado.[http://online.wsj.com/public/article/SB115040765329081636-T5DQ4jvnwqOdVvsP_XSVG_lvgik_20060628.html Scientist's Study Of Brain Genes Sparks a Backlash.][[The Wall Street Journal]]. June 16, 2006.</ref> |
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A 2005 literature review article on the links between race and intelligence in [[American Psychologist]] stated that no gene has been shown to be linked to intelligence, "so attempts to provide a compelling genetic link of race to intelligence are not feasible at this time".<ref name="Intelligence, Race, and Genetics"/> Two 2007 studies found that DTNBP1 and CHRM2 appear to influence intelligence depending on which allele of it a person carries.<ref>Janneke R Zinkstok, Odette de Wilde, Therese AMJ van Amelsvoort, Michael W Tanck, Frank Baas and Don H Linszen (2007). "Association between the DTNBP1 gene and intelligence: a case-control study in young patients with schizophrenia and related disorders and unaffected siblings". ''Behavioral and Brain Functions'' 3:19 doi:10.1186/1744-9081-3-19</ref><ref> Dick DM, Aliev F, Kramer J, Wang JC, Hinrichs A, Bertelsen S, Kuperman S, Schuckit M, Nurnberger J Jr, Edenberg HJ, Porjesz B, Begleiter H, Hesselbrock V, Goate A, Bierut L (2007). “Association of CHRM2 with IQ: converging evidence for a gene influencing intelligence.” Behavioral Genetics 37(2):265-72</ref> However, a study published in 2009 by Deary ''et al.''. failed to find evidence of an association between these genes and general intelligence, stating "there is still almost no replicated evidence concerning the individual genes, which have variants that contribute to intelligence differences".<ref>{{cite journal|year =2009|title=Genetic foundations of human intelligence |url=http://www.springerlink.com/content/c7542mt244856455/fulltext.html|doi=0.1007/s00439-009-0655-4|last=Deary}}</ref> |
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=== Health === |
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[[Image:Lead levels children.png|thumb|250px|right|Percentage of children aged 1-5 with [[blood lead level]]s ''at least'' 10 µg/dL. Black and Hispanic children have measurably higher levels than white children. High levels of lead at an early age may affect intelligence.]] |
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{{Main|Health and intelligence}} |
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{{Main|Race and health}} |
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Numerous explanations beside genetics have been proposed to account for the IQ gaps in the U.S.<ref>Joel Wiesen, "[http://appliedpersonnelresearch.com/papers/adimpact.pdf An Annotated List of Many Possible Reasons for the Black-White Mean Score Differences Seen With Many Cognitive Ability Tests: Notes to File]," Applied Personnel Research, March 18, 2005.</ref> |
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High rates of low birth-weight babies, lower rates of breastfeeding, and exposure to toxins are some factors. The [[Flynn effect]] is often cited as evidence that average IQ scores have changed greatly and rapidly, for reasons poorly understood, thus the IQ gap between races could change in the future or is changing, especially if the Flynn effect started earlier for Whites. |
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High levels of lead at an early age may affect intelligence; studies indicate that black and Hispanic children have measurably higher levels than white children. A 10 µg/dL increase in blood lead at 24 months of age is associated with a 5.8-point lower IQ later in life.<ref>[http://pediatrics.aappublications.org/cgi/content/abstract/90/6/855 Low-Level Lead Exposure, Intelligence and Academic Achievement: A Long-term Follow-up Study] David C. Bellinger PhD, MSc1, Karen M. Stiles PhD, MN1, and Herbert L. Needleman MD1. Pediatrics Vol. 90 No. 6 December 1992, pp. 855-861</ref> In 1976 77.8% of all children had ''at least'' this much lead in their blood.<ref>[http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5420a5.htm Blood Lead Levels — United States, 1999–2002] CDC.</ref> |
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Exposure to lead is frequently attributed to housing conditions including lead based paint, which is no longer used but has accumulated in older buildings; people of lower economic means are more frequently exposed to lead from housing.<ref>[http://www.mindfully.org/Pesticide/NAACP-Mfume-Lead.htm Mfume Calls Lead Paint Poisoning "The Silent Epidemic"] NAACP Press Release 17 July 2001</ref> |
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===Quality of education=== |
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{{See also|Environment and intelligence}} |
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Some researchers have written that studies that find test performance gaps between races even after adjusting for education level, such as the analysis found in ''[[The Bell Curve]]'', fail to adjust for the quality of education. Not all high school graduates or college graduates have received the same quality of education. A 2006 study reported that years of education is an inadequate measure of the educational experience among multicultural elders, and that adjusting for quality of education greatly reduced the overall effect of racial differences on the tests.<ref>''[http://www.journals.cambridge.org/action/displayAbstract?fromPage=online&aid=106211Reading level attenuates differences in neuropsychological test performance between African American and White elders]'' Jennifer J. Manly, Diane M. Jacobs, [[Pegah Touradji]], Scott A. Small and Yaakov Stern</ref> A 2004 study reported that quality of education and cultural experience influence how older African Americans approach neuropsychological tasks and concluded that adjustment for these variables may improve specificity of neuropsychological measures.<ref>''Acculturation, Reading Level, and Neuropsychological Test Performance Among African American Elders'' Jennifer J. Manly, Desiree A. Byrd, Pegah Touradji, Yaakov Stern</ref> Yet another study reported that, although significant differences were observed between the ethnic groups when matched for years of education, equating for literacy level eliminated all performance differences between African Americans and European Americans on both cancellation tasks which assess visual scanning<ref>''Cancellation test performance in African American, Hispanic, and White elderly'' Desiree A. Byrd, Pegah Touradji, Ming-Xin Tang and Jennifer J. Manly</ref> (like reaction time tests, cancellation task tests are sometimes regarded as "culture free" tests of intelligence). Eric A. Hanushek and Steven G. Rivkin wrote in their 2006 book that unequal distributions of inexperienced teachers and of racial concentrations in schools can explain all of the increased achievement gap between grades 3 and 8.<ref>''School Quality and the Black-White Achievement Gap'' Eric A. Hanushek and Steven G. Rivkin 2006</ref> In recent years there have also been studies into the degrees in which many minorities, especially blacks, have internalized pathologies about their supposed lack of intelligence and the effects it has in their self-confidence, quality of learning and achievement.<ref>[http://books.google.com/books?id=t9OdPPLIgMAC&pg=PA262&lpg=PA262&dq=black+doctors,+IQ&source=bl&ots=Lls_BO9b_v&sig=mjY876k-_Ai6rASLWa_-KkuXE6g&hl=en&ei=s9mlSaVxj5y3B9LQpNkE&sa=X&oi=book_result&resnum=13&ct=result Race and Intelligence: Separating Science from Myth By Jefferson M. Fish]</ref> Additionally, Jensen's studies (Jensen, 1974b) show that 7% of black children of black professionals have mean IQs below that of white children from low-income families, yet this seems to have little to no detriment on the black children's success.<ref>[http://books.google.com/books?id=UW9cjBo_nCIC&pg=PA507&lpg=PA507&dq=black+professionals,+IQ&source=bl&ots=rMwdUKGrdR&sig=O5hputBF8EJzrc3__oWATWptbmM&hl=en&ei=qtylSbDANpPHtgesnJzOBA&sa=X&oi=book_result&resnum=12&ct=resultRace, Social Class, and Individual Differences in I.Q. By Sandra Scarr]</ref> |
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A 2004 study in [[South Africa]] found highly significant effects for both level and quality of education within the black African first language groups taking the [[Wechsler Intelligence Scale for Children|Wechsler]] IQ tests. The scores of black African first language groups with advantaged education were comparable with the US standardization, whereas scores for black African first language participants with disadvantaged education were significantly lower than this. The study cautioned that faulty conclusions may be drawn about the effects of ethnicity and the potential for [[neuropsychological]] [[misdiagnosis]].<ref>''Cross-cultural Effects on IQ Test Performance: A Review and Preliminary Normative Indications on WAIS-III Test Performance''Journal of Clinical and Experimental Neuropsychology Volume 26, Number 7 / October 2004</ref> |
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=== Racial discrimination in education === |
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Roslyn Arlin Mickelson writes that racial discrimination in education arises from actions of institutions or individual state actors, their attitudes and ideologies, or processes that systematically treat students from different racial/ethnic groups disparately or inequitably.<ref>''When Are Racial Disparities in Education the Result of Racial Discrimination? A Social Science Perspective'' by Roslyn Arlin Mickelson University of North Carolina at Charlotte</ref> Despite advancement in education reform efforts, to this day African American students continue to experience inequities within the educational system. Hala Elhoweris, Kagendo Mutua, Negmeldin Alsheikh and Pauline Holloway conducted a study of the effect of students' ethnicity on teachers' educational decision making. The results of this study indicated that the student's ethnicity did make a difference in the teachers' referral decisions for [[Gifted education|gifted and talented]] educational programs.<ref>''Effect of Children's Ethnicity on Teachers' Referral and Recommendation Decisions in Gifted and Talented Programs'' Journal article by Negmeldin Alsheikh, Hala Elhoweris, Pauline Holloway, Kagendo Mutua; Remedial and Special Education, Vol. 26, 2005</ref> Recently, a number of scholars have examined the issue of disproportionate representation of minority students in [[special education]]programs<ref>(Salend, Garrick Duhaney, & Montgomery, 2002; Townsend, 2002)</ref><ref>''Racial Inequity in Special Education.'' Losen, Daniel J., Ed.; Orfield, Gary, Ed. Harvard Education Publishing Group.</ref> |
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Teachers' perceptions of a students cultural background may affect school achievement. African American students with African American cultural backgrounds, for example, have been found to benefit from culturally responsive teaching.<ref>(Gay, 2000; Irvine & Armento, 2001; Ladson-Billings, 1994, 2001)</ref> In a 2003 study researchers found that teachers perceived students with African American culture-related movement styles as lower in achievement, higher in aggression, and more likely to need special education services than students with standard movement styles irrespective of race or other academic indicators.<ref>''The Effects of African American Movement Styles on Teachers' Perceptions and Reactions'' Journal article by Scott T. Bridgest, Audrey Davis Mccray, La Vonne I. Neal, Gwendolyn Webb-Johnson; Journal of Special Education, Vol. 37, 2003</ref> |
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Ellis Cose writes that low expectations may have a negative impact on the achievement of minorities. He writes that black people did not need to read ''The Bell Curve'' to be aware of the low expectations held for them by the majority culture. He recalls examples of low expectations from his teachers in school who regarded his use of [[AAVE]] as "laziness" and teachers who did not feel it was important to purchase new text books because they did not expect the students to be able to read anything complex. He contrasts these low expectations with the high expectations philosophy of [[Xavier University of Louisiana|Xavier University]] where, using the ideas Whimbey articulated in his book ''Intelligence can be Taught'' teachers created a program called SOAR. SOAR raised the performance of black students and lead Xavier to become the university that sends the greatest number of black students to medical school in the United States. The SOAR program produced gains equivalent to 120 points on an [[SAT test]]. Cose writes that "..we must treat people, whatever their color, as if they have unlimited intellectual capacity."<ref>''Color-Blind'' Ellis Cose. Page 50</ref> |
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[[Structural equation models]] have been used to test for possible uncommon factors in the development of children belonging to different ethnic groups, which would include the results of racial discrimination. However, these tests have concluded that black, white, Hispanic and Asian children follow developmental processes which are "nearly identical."<ref>Rowe, David C., Vazsonyi, Alexander T. and Flannery, Daniel J. [http://www.nlsbibliography.org/qtitle.php3?myrow[0]=2115 No More Than Skin Deep: Ethnic and Racial Similarity in Developmental Process]. Psychological Review 101,3 (July 1994): 396-413</ref><ref>Rowe, David C. and Hobart H. Cleveland.[http://dx.doi.org/10.1016/S0160-2896(96)90004-5 Academic achievement in Blacks and Whites: Are the developmental processes similar?] Intelligence Volume 23, Issue 3, November-December 1996, Pages 205-228.</ref> |
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=== Caste-like minorities === |
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[[File:Group differece table from Inequality by Design.png|thumb|400px]]The book ''[[Inequality by Design: Cracking the Bell Curve Myth]]'' (1996) claims that it is not lower average intelligence that leads to the lower status of racial and ethnic minorities, it is instead their lower status that leads to their lower average intelligence test scores. To substantiate this claim, the book presents a table comparing social status or caste position with test scores and measures of school success in several countries around the world.<ref name="bell myth">''[http://press.princeton.edu/chapters/s5877.html Inequality by Design: Cracking the Bell Curve Myth]'' by Claude S. Fischer, Michael Hout, Martín Sánchez Jankowski, Samuel R. Lucas, Ann Swidler, and Kim Vos. Page 192.</ref> The authors note, however, that the comparisons made in the table do not represent the results of all relevant findings, nor do they reflect the fact that the tests and procedures varied greatly from study to study. The comparison of Jews and Arabs, for example, is based on a news report that, in 1992, 26% of Jewish high school students passed their matriculation exam, as opposed to 15% of Arab students.<ref name="bell myth">''[http://press.princeton.edu/chapters/s5877.html Inequality by Design: Cracking the Bell Curve Myth]'' by Claude S. Fischer, Michael Hout, Martín Sánchez Jankowski, Samuel R. Lucas, Ann Swidler, and Kim Vos. Page 191.</ref> |
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===Other views=== |
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[[Jared Diamond]]'s ''[[Guns, Germs and Steel]]'' argues that historical differences in economic and technological development for different geographic areas can be explained by differences in geography (which affects factors like population density and spread of new technology) and differences in available crops and domesticatable animals. [[Richard E. Nisbett|Richard Nisbett]] argues in his 2004 ''The Geography of Thought'' that some of these regional differences shaped lasting cultural traits, such as the collectivism required by East Asian rice [[irrigation]], compared with the individualism of [[Ancient Greece|ancient Greek]] herding, maritime mercantilism, and money crops wine and olive oil<ref>(pp. 34-35).</ref> However, it has been suggested that these environmental differences may operate in part by [[natural selection|selecting]] for higher levels of IQ.<ref>This theory is discussed by Jensen (1998b) (pp. 435-437), Lynn (1991b) and Rushton (2000) in general and by both Wade (2006) and[http://www.isteve.com/diamond.htm Steve Sailer] with respect to ''Guns, Germs, and Steel''. See[[Race and intelligence (Explanations)#Rushton's application of r-K theory]]. .. Voight et al. (2006) state generally that "a number of recent studies have detected more signals of adaptation in non-African populations than in Africans, and some of those studies have conjectured that non-Africans might have experienced greater pressures to adapt to new environments than Africans have" (Kayser et al. 2003, Akey et al. 2004, Storz et al. 2004, Stajich and Hahn 2005, Carlson et al. 2005).</ref> |
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Differing rates of economic growth have also been attributed to numerous factors other than racial IQ gaps such as local availability of resources, climate, and sociopolitical factors. See for example the [[Global Competitiveness Report]], the [[Ease of Doing Business Index]], and the[[Index of Economic Freedom]] or works by [[Kenneth Pomeranz]],<ref>Pomeranz, Kenneth (2001).''The Great Divergence''. Princeton, NJ: Princeton University Press.</ref> [[Eric Jones]],<ref>Jones, Eric (1997). ''The European Miracle''. Cambridge: Cambridge University Press.</ref> [[Joel Mokyr]],<ref>Mokyr, Joel (1992). ''The Lever of Riches''. Oxford: Oxford University Press.</ref> and [[Douglass C. North]].<ref>North, Douglass (1976). ''The Rise of the Western World''. Cambridge: Cambridge University Press.</ref> |
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=== Debating the hereditarian position === |
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A few of the notable proponents of the partly genetic hypothesis are [[Raymond B. Cattell]],[[Arthur Jensen]] and [[Hans Eysenck]]. |
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[[J. Philippe Rushton|Rushton]] and [[Arthur Jensen|Jensen]] examined 10 categories of research evidence from around the world to contrast "a hereditarian model" (50% genetic-50% cultural) and a culture-only model (0% genetic-100% cultural). Their article "''Thirty Years of Research on Race Differences in Cognitive Ability''" was published in the [[APA]] journal ''Psychology, Public Policy and Law'' showing evidence that they believe supports the hereditarian model.<ref>http://psychology.uwo.ca/faculty/rushtonpdfs/PPPL1.pdf Thirty Years of Research on Race Differences in Cognitive Ability</ref><ref>http://www.innovations-report.de/html/berichte/studien/bericht-43536.htmlBlack-White-East Asian IQ differences at least 50% genetic, major law review journal concludes</ref> Rushton and Jensen (2005a) believe that the best explanation for the gap is that 50%-80% of the group differences in average US IQ is genetic.<ref>Rushton and Jensen (2005a), cited in "[http://www.eurekalert.org/pub_releases/2005-04/cdri-bai042505.php Black-White-East Asian IQ differences at least 50% genetic, scientists conclude in major law journal]", and Murray (2005)</ref> |
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Other evidence, such as the [[Minnesota Transracial Adoption Study]], certain racial admixture studies, behavior genetic modeling of group differences, "life-history" traits, and evolutionary explanations have also been proposed to indicate a genetic contribution to the IQ gaps and explain how these arose.<ref>Reviewed by Rushton and Jensen (2005).</ref> |
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==== Outdated methodology ==== |
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A 2006 paper by Professor Denny Borsboom argues that mainstream contemporary test analysis does not reflect substantial recent developments in the field and "bears an uncanny resemblance to the psychometric state of the art as it existed in the 1950s."<ref>[http://users.fmg.uva.nl/dborsboom/papers.htm The attack of the psychometricians]. Denny Borsboom. Psychometrika Vol. 71, No. 3, 425–440. September 2006.</ref> It also claims that some of the most influential recent studies on group differences in intelligence, in order to show that the tests are unbiased, use outdated methodology. In particular the reliance on[[classical test theory]] rather than more sophisticated measurement models as found in [[item response theory]]. In response to criticism proponents of the genetic hypothesis claim they use a standard for intelligence known as g. g is measured by performance on test items without the influence of language or math. |
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==== Test construction ==== |
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While the existence of average IQ test score differences has been a matter of accepted fact for decades, a great deal of controversy exists among scholars over the question of whether these score differences reflected real differences in cognitive ability. Some claim that there is no evidence for test bias since IQ tests are equally good predictors of IQ-related factors (such as school performance) for U.S. Blacks and Whites.<ref name="APA">Neisser, U., Boodoo, G., Bouchard, T. J. Jr., Boykin, A. W., Brody, N., Ceci, S. J. et al. (1996). Intelligence: Knowns and unknowns. American Psychologist, 51, 77–101.</ref> The performance differences persist in tests and testing situations in which care has been taken to eliminate bias.<ref name="APA"/> It has also been suggested that IQ tests are formulated in such a way as to disadvantage minorities.<ref name="APA" /> Controlled studies have shown that test construction does not substantially contribute to the IQ gap.<ref name="APA" /> However, some psychometricians are not satisfied that the question of test bias is fully answered by these results.<ref>Dolan, C. V. (1997). A note on Schönemann's refutation of Spearman's hypothesis. Multivariate Behavioral Research, 32, 319–325.</ref><ref>Dolan, C. V. (2000). Investigating Spearman's hypothesis by means of multi-group confirmatory factor analysis. Multivariate Behavioral Research, 35, 21–50.</ref><ref>Dolan, C. V., & Hamaker, E. L. (2001). Investigating Black-White differences in psychometric IQ: Multi-group confirmatory factor analyses of WISC-R and K-ABC and a critique of the method of correlated vectors. In F. Columbus (Ed.), Advances in psychology research (Vol. 6, pp. 30–59). Huntington, NY: Nova Science.</ref> |
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The preponderance of evidence indicates that IQ tests measuring [[general intelligence]] are crossculturally valid. There is little or no evidence of population-specific cultural effects apart from the obvious example of language bias.<ref>http://www.charlesdarwinresearch.org/PRSL2007.pdf</ref> For example, [[Robert Sternberg]] et al. found that the IQ of 12- to 15-year-old Kenyans predicted school grades at about the same level as they do in the West.<ref>Sternberg, R. J., Nokes, C., Geissler, P. W., Prince, R., |
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Okatcha, F., Bundy, D. A. & Grigorenko, E. L. 2001 The |
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relationship between academic and practical intelligence: |
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a case study in Kenya. Intelligence 29, 401–418.</ref> IQ also predicted university performance equally well in African and non-African engineering students in South Africa in a 2004 study.<ref>Construct validity of Raven’s Advanced Progressive Matrices for African and non-African engineering students in South Africa.</ref> Salgado et al. (2003) demonstrated the international generalizability of general mental ability across 10 member countries of the[[European Community]] and differences in a nation’s culture, religion, language, socioeconomic level or employment legislation did not affect the predictive validity of IQ tests.<ref>Salgado, J. F., Anderson, N., Moscoso, S., Bertua, C. & |
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Fruyt, F. D. 2003 International validity generalization of |
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GMA and cognitive abilities: a European community |
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meta-analysis. Pers. Psychol. 56, 573–605.</ref> |
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However, other studies have found evidence for bias. A 2005 study finds some evidence that the[[WAIS-R]] is not culture-fair for Mexican Americans.<ref>[http://asm.sagepub.com/cgi/content/abstract/12/3/303 Culture-Fair Cognitive Ability Assessment] Steven P. Verney Assessment, Vol. 12, No. 3, 303-319 (2005)</ref> Other recent studies have questioned the culture-fairness of IQ tests when used in South Africa.<ref>[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=15742541&dopt=Abstract Cross-cultural effects on IQ test performance: a review and preliminary normative indications on WAIS-III test performance.]Shuttleworth-Edwards AB, Kemp RD, Rust AL, Muirhead JG, Hartman NP, Radloff SE. J Clin Exp Neuropsychol. 2004 Oct;26(7):903-20.</ref><ref>[http://www.blackwell-synergy.com/doi/abs/10.1111/j.1468-2389.2006.00346.x Case for Non-Biased Intelligence Testing Against Black Africans Has Not Been Made: A Comment on Rushton, Skuy, and Bons (2004)] 1*, Leah K. Hamilton1, Betty R. Onyura1 and Andrew S. Winston International Journal of Selection and Assessment Volume 14 Issue 3 Page 278 -September 2006</ref> |
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==== Lack of direct evidence ==== |
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Nisbett (2005) argues that many studies find results that do not support the genetic hypothesis. They include studies on IQ and skin color that reported that the average correlation between skin color and IQ is .1 (the average correlation between IQ and judged “Negroidness” of features is even lower); IQ and self-reported European ancestry; IQ and blood groups showing degree of European Ancestry; IQ among children in post WWII Germany born to black and white American soldiers; and IQ among mixed-race children born to either a black or a white mother. He argues that these are direct tests of the genetic hypothesis and of more value than indirect variables, such as skull size and reaction time. He argues that "There is not a shred of evidence in this literature, which draws on studies having a total of five very different designs, that the gap has a genetic basis." He argues further that many intervention and adoption studies also find results that do not support the genetic hypothesis. He also argues "that the Black-White IQ gap has lessened considerably in recent decades."<ref>[http://taxa.epi.umn.edu/~mbmiller/journals/pppl/200504/2/302-2.html Heredity, Evironment, and Race differences in IQ. A Commentary on Rushton and Jensen (2005)] Richard E. Nisbett, Psychology, Public Policy, and Law: June 2005 Vol. 11, No. 2, 302-310</ref> Hunt and Carlson<ref name="autogenerated2">Hunt, Earl & Carlson, Jerry. Considerations Relating to the Study of Group Differences in Intelligence. Perspectives on Psychological Science 2 (2), 194-213.</ref> argue that Nisbett's interpretations are far too strong in light of problems with these studies that have been recognized for decades.<ref>Loehlin, J.C., Lindzey, G., & Spuhler, J. (1975). Racial Differences in Intelligence. San Francisco: Freeman.</ref> Gottfredson writes that the studies Nisbett cites "actually lack the ability to rule out any hypothesis at all, genetic or not".<ref>http://www.udel.edu/educ/gottfredson/reprints/2007doublestandards.pdf</ref> |
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Dickens (2005) states that "Although the direct evidence on the role of environment is not definitive, it mostly suggests that genetic differences are not necessary to explain racial differences. Advocates of the hereditarian position have therefore turned to indirect evidence...The indirect evidence on the role of genes in explaining the black-white gap does not tell us how much of the gap genes explain and may be of no value at all in deciding whether genes do play a role. Because the direct evidence on ancestry, adoption, and cross-fostering is most consistent with little or no role for genes, it is unlikely that the black-white gap has a large genetic component."<ref>[http://www.futureofchildren.org/usr_doc/pg_55_dickens.pdf Genetic Differences and School Readiness] Dickens, William T. The Future of Children - Volume 15, Number 1, Spring 2005, pp. 55-69</ref> |
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[[Roland G. Fryer Jr|Fryer]] and [[Steven Levitt|Levitt]] (2006), with data from "the first large, nationally representative sample" of its kind, report finding only a very small racial difference when measuring mental function for children aged eight to twelve months, and that even these differences disappear when including a "limited set of controls". "On tests of intelligence, Blacks systematically score worse than Whites, whereas Asians frequently outperform Whites. Some have argued that genetic differences across races account for the gap. Using a newly available nationally representative data set that includes a test of mental function for children aged eight to twelve months, we find only minor racial differences in test outcomes (0.06 standard deviation units in the raw data) between Blacks and Whites that disappear with the inclusion of a limited set of controls. The only statistically significant racial difference is that Asian children score slightly worse than those of other races." They argue that their report poses "a substantial challenge to the simplest, most direct, and most often articulated genetic stories regarding racial differences in mental function." They conclude that "to the extent that there are any genetically-driven racial differences in intelligence, these gaps must either emerge after the age of one, or operate along dimensions not captured by this early test of mental cognition."<ref>Roland G. Fryer Jr. and Steven D. Levitt, "[https://mitpress.mit.edu/journals/pdf/rest_86_2_447_0.pdf Understanding the Black-White Test Score Gap in the First Two Years of School]," ''The Review of Economics and Statistics'' 86, no. 2 (2004). [http://post.economics.harvard.edu/faculty/fryer/papers/fryer_levitt_ecls_babies.pdfTesting for Racial Differences in the Mental Ability of Young Children]</ref> |
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==== Source of funding ==== |
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Vocal proponents of partially genetic explanations of race/IQ correlation, such as Rushton, Lynn, and Jensen, have been criticized for receiving funding from the [[Pioneer Fund]], a group that has been reported as having had ties to German [[eugenics|eugenicists]] working under the[[Nazi]] regime as well as to other US eugenicists of the early 20th century.<ref name="Berlet">Southern Poverty Law Center[http://www.splcenter.org/intel/intelreport/article.jsp?aid=50 Into the Mainstream; An array of right-wing foundations and think tanks support efforts to make bigoted and discredited ideas respectable.] Retrieved April 15, 2008.</ref><ref>[http://www.albanylawreview.org/archives/65/3/TheAmericanBreed-NaziEugenicsandtheOriginsofthePioneerFund.pdf ''The American Breed: Nazi Eugenics and the Origins of the Pioneer Fund''] Retrieved Oct 27, 2009.</ref> The [[Southern Poverty Law Center]]considers the [[Pioneer Fund]] to be a [[hate group]]. Rushton is the current head of the Pioneer Fund and has spoken at conferences of the [[American Renaissance magazine]], in which he has also published articles.<ref>http://www.splcenter.org/intel/intelreport/article.jsp?pid=214#27</ref> |
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Proponents of genetic explanations of race-IQ correlation have in turn accused their critics of[[scientific misconduct|suppressing scientific debate]] in the name of [[political correctness]]. They claim harassment and interference with both their work and funding. The Pioneer Fund, whose stated purpose is "to advance the scientific study of heredity and human differences", makes "no grants to individuals but only to research institutions, mainly universities, mostly for specialized 'niche' projects, which have difficulty attracting funds from government sources or from larger foundations".<ref>[http://www.pioneerfund.org/ The Pioneer Fund, Inc.]</ref> |
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==History of debate== |
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===Development of the debate=== |
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The idea that there are differences in the brain structures or sizes of different racial and ethnic groups was widely held and studied during the 19th and early 20th centuries.<ref>Broca 1873; Bean 1906; Mall 1909; Morton 1839; Pearl 1934; Vint 1934</ref> During this time period, research on race and intelligence was often used to claim that one race was superior to another, justifying the poor status and treatment of the "inferior" race.<ref>''[[Social Darwinism]], [[Scientific racism|Scientific Racism]], and the Metaphysics of Race'' Rutledge M. Dennis The Journal of Negro Education, Vol. 64, No. 3, Myths and Realities: African Americans and the Measurement of Human Abilities (Summer, 1995), pp. 243–252</ref> |
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Sir [[Francis Galton]], a [[psychometrician]] and [[polymath]] (1822–1911), spurred interest in the study of mental abilities, particularly as they relate to [[heredity]] and [[eugenics]].<ref>[http://iml.jou.ufl.edu/projects/Spring02/Holland/Galton.htm Eugenics: America's Darkest Days]</ref> |
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The scientific debate on the contribution of [[nature versus nurture]] to individual and group differences in intelligence can be traced back to at least the mid-19th century.<ref>Degler 1992; Loehlin et al. 1975</ref> Beginning in the 1930s, race difference research and [[hereditarianism]] — the belief that [[genetics]] are the primary cause of differences in intelligence among human groups — began to fall out of favor in psychology and anthropology after major internal debates.<ref>According to historian of psychology Graham Richards there was widespread critical debate within psychology about the conceptual underpinnings of this early race difference research (Richards 1997). These include Estabrooks (1928) two papers on the limitations of methodology used in the research; Dearborn and Long’s (1934) overview of the criticisms by several psychologists (Garth, Thompson, Peterson, Pinter, Herskovits, Daniel, Price, Wilkerson, Freeman, Rosenthal and C.E. Smith) in a collection they edited and Klineburg, who wrote three major critiques, one in 1928, and two in 1935. Richards also notes that with over a 1000 publications within psychology during the interwar years there had been a large internal debate. Towards the end of the time period almost all those publishing, including most of those who began with a pro-race differences stance, were firmly arguing against race differences research. Richards regards the scientific controversy to be dead at this point, although he also suggests reasons for its re-emergence in the late nineteen sixties.</ref> By 1961, the mainstream view was that there were no race differences in intelligence, or if there were, they were solely the result of environmental factors.<ref>Lynn 2001 pp. 67–69</ref> |
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The most controversial and most publicized part of the debate is whether group IQ differences also reflect a genetic component. [[Hereditarianism]] hypothesizes that a genetic contribution to intelligence could include genes linked to neuron structure or function, [[neuroscience and intelligence|brain size]] or metabolism, or other physiological differences which could vary with biogeographic ancestry. |
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===The 1970s debates=== |
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:''See also: [[Arthur Jensen]]'' |
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Publication in 1969 of [[psychology]] psychologist [[Arthur Jensen]]'s controversial article, "How Much Can We Boost IQ and School Achievement?" <ref>''Harvard Educational Review'' 39: 1-123</ref> triggered the modern debate. In it, he wrote, "All we are left with are various lines of evidence, no one of which is definitive alone, but which, viewed together, make it a not unreasonable hypothesis that genetic factors are strongly implicated in the average negro-white intelligence difference. The preponderance of evidence is, in my opinion, less consistent with a strictly environmental hypothesis than with a genetic hypothesis, which, of course, does not exclude the influence of environment or its interaction with genetic factors." [[Philosophy|Philosopher]] [[Peter Singer]] wrote that Jensen's article was widely reported in the popular press "as an attempt to defend racism on scientific grounds".<ref>[http://www.cambridge.org/catalogue/catalogue.asp?isbn=9780521439718 ''[[Practical Ethics]]'' 2nd edition by Peter Singer] 1999 Princeton University Press ISBN 978-0521439718</ref> |
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An advocate of [[population control]], physicist [[William Shockley]] focused on questions of race, intelligence, and [[eugenics]] and published several controversial papers arguing that intelligence is primarily hereditary.<ref>[http://www.pbs.org/transistor/album1/shockley/shockley3.html William Shockley, Part 3 of 3]</ref><ref>[http://encarta.msn.com/encyclopedia_761562270/william_shockley.html William Shockley - MSN Encarta]</ref> He postulated that the higher reproduction rate of those with lower intelligence has a [[dysgenic]] effect on society and proposed that individuals with [[IQ]]s below 100 be paid to undergo voluntary [[Sterilization (surgical procedure)|sterilization]].<ref>{{cite book | last = Shockley | first = William | authorlink = William Shockley | title = Shockley on Eugenics and Race: The Application of Science to the Solution of Human Problems | isbn = 978-1878465030 | year = 1992 | publisher = Scott-Townsend Publishers | location = Washington, D.C.}}</ref> Biologists and geneticists criticized his theories, comparing them to rationale used by the [[Nazis]] in carrying out their genocidal policies. Criticism of Shockley's racial ideas appeared in scientific journals and was reflected in the popular press. |
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Arguing that environmental factors could explain the black-white IQ gap,<ref>[http://www.amazon.com/gp/reader/0231133960/ A Genetic and Cultural Odyssey: The Life and Work of L. Luca Cavalli-Sforza by Linda Stone, pages 76, 168 ]ISBN 0231133960.</ref> population geneticist [[Luigi Luca Cavalli-Sforza]] debated Jensen and Shockley. |
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===The 1990s Bell Curve debates=== |
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:''See also: [[The Bell Curve]]'' |
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Discussion centers on whether group differences in average IQ are purely [[social]], [[economic]], and [[cultural]] or are hard-wired in [[genetics]]. The [[American Anthropological Association]] has declared that "differentiating species into biologically defined 'races' has proven meaningless and unscientific as a way of explaining variation,"<ref name="AAA 1994">{{cite web | author= [[American Anthropological Association]] | year= 1994 | url= http://www.aaanet.org/stmts/race.htm | title= Statement On "Race" And Intelligence | format= | work= | publisher= American Anthropological Association | date = December 19, 2005}}</ref> while the [[American Psychological Association]] has stated that the causes of inter-group IQ differences are unknown.<ref name="Neisser 1996"/> |
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Academics such as [[Michael Levin]] and [[J. Philippe Rushton]] differ from the [[American Anthropological Association]] in their claims that IQ score differences are traceable to genetics. [[Stephen Jay Gould]],<ref>{{citation|first=Stephen Jay|last=Gould|title=The Mismeasure of Man| publisher=Sagebrush Education Resources|year=1996|id=ISBN 0613181301}}</ref> [[Richard Levin]], [[Richard Lewontin]]<ref> {{citation| first=Richard|last=Lewontin|title=It Ain't Necessarily So: The Dream of the Human Genome and Other Illusions|publisher=New York review of Books|year=2001|id=ISBN 0940322951}}</ref> and [[Joseph L. Graves]]<ref> [http://ant.sagepub.com/cgi/content/abstract/2/2/131 What a tangled web he weaves: Race, reproductive strategies and Rushton's life history theory] by Joseph L Graves</ref> contend that the proponents of the genetics explanation are wrong. |
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The book ''[[The Bell Curve]]'' by [[psychologist]] [[Richard Herrnstein]] and [[American Enterprise Institute]] political scientist [[Charles Murray (author)|Charles Murray]] wrote: "The debate about whether and how much genes and environment have to do with ethnic differences remains unresolved. The universality of the contrast in nonverbal and verbal skills between East Asians and European whites suggests, without quite proving, genetic roots." Herrnstein and Murray said intelligence is a better predictor of many factors including financial income, job performance, unwed pregnancy, and crime than parents' [[socioeconomic status]] or education level. |
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''The Bell Curve'' attracted attention, both critical of and in defense of the book. Critics called it [[scientific racism]]. Several books were written in response, including ''[[The Bell Curve Debate]]'' and ''[[The Mismeasure of Man]]'' (second edition) and scholarly associations released statements of opinion. |
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The [[American Psychological Association]]'s Board of Scientific Affairs in 1995 established a task force which produced a report, "[[Intelligence: Knowns and Unknowns]]"<ref name="Neisser 1996"/> The psychology association report authors wrote that IQ scores have high predictive validity for individual differences in school achievement, for adult occupational status, even when variables such as education and family background have been statistically controlled, and they said individual differences in intelligence are substantially influenced by genetics (75% in adults). Contrary to Herrnstein and Murray's findings{{Citation needed|date=December 2009}}, they wrote that prolonged malnutrition during childhood does have long-term intellectual effects. The APA report confirmed the existence of racial IQ differences, while remaining agnostic about their underlying causes: |
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<blockquote>The differential between the mean intelligence test scores of Blacks and Whites (about one standard deviation, although it may be diminishing) does not result from any obvious biases in test construction and administration, nor does it simply reflect differences in socio-economic status. Explanations based on factors of caste and culture may be appropriate, but so far have little direct empirical support. There is certainly no such support for a genetic interpretation. At present, no one knows what causes this differential.<ref>[http://faculty.mwsu.edu/psychology/Laura.Spiller/4503_Tests/intelligence_knowns_and_unknowns.pdf American Psychological Association findings on predictive value of intelligence tests]</ref></blockquote> The APA report concluded with a call for more reflection in debates on intelligence and for a "shared and sustained effort" for more research to answer the many unanswered questions that remain. |
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Eleven critical responses appeared in the January 1997 issue of ''American Psychologist'', suggesting ways in which the APA report could have been improved. The responses by Richard Lynn and J. Philippe Rushton disputed the task force's conclusion that there is no direct evidence for a genetic interpretation of the IQ difference between blacks and whites.<ref>Neisser, U. (1997). "Never a Dull Moment". ''American Psychologist'' 52: 79-81.[http://socrates.berkeley.edu/~maccoun/PP279_Neisser2.html]</ref> |
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On December 13, 1994, psychologist [[Linda Gottfredson]] and 51 specialists in intelligence and related fields asserted on the opinion page of the ''[[Wall Street Journal]]'' <ref name="gottfredson">Gottfredson, Linda (December 13, 1994), "Mainstream Science on Intelligence". ''[[Wall Street Journal]]'', p A18.</ref> that IQ bell curves differ across racial and ethnic groups for varying reasons. They maintained that, "Most experts believe that environment is important in pushing the bell curves apart, but that genetics could be involved too."<ref>[http://www.udel.edu/educ/gottfredson/reprints/1997mainstream.pdf Mainstream science on intelligence]</ref> |
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In 1994, the [[American Anthropological Association]] declared itself "deeply concerned by recent public discussions which imply that intelligence is biologically determined by race. Repeatedly challenged by scientists, nevertheless these ideas continue to be advanced. Such discussions distract public and scholarly attention from and diminish support for the collective challenge to ensure equal opportunities for all people, regardless of ethnicity or phenotypic variation."<ref>[http://www.aaanet.org/stmts/race.htm AAA Statement on "Race" and Intelligence]</ref> |
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In August 1995, at the [[National Bureau of Economic Research]] [[economist]] Sanders Korenman and [[Harvard University]] sociologist [[Christopher Winship]] claimed to have found certain errors in Murray and Herrnstein's methodology. Korenman and Winship concluded: "... there is evidence of substantial bias due to measurement error in their estimates of the effects of parents` socioeconomic status. In addition, Herrnstein and Murray`s measure of parental socioeconomic status (SES) fails to capture the effects of important elements of family background (such as single-parent family structure at age 14). As a result, their analysis gives an exaggerated impression of the importance of IQ relative to parents` SES, and relative to family background more generally. Estimates based on a variety of methods, including analyses of siblings, suggest that parental family background is at least as important, and may be more important than IQ in determining socioeconomic success in adulthood."<ref> http://ssrn.com/abstract=225294 Korenman, Sanders and Winship, Christopher, "A Reanalysis of The Bell Curve" (August 1995). NBER Working Paper Series, Vol. w5230, 1995.</ref> |
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==Significance of group IQ differences== |
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:''See also: [[Intelligence quotient#Practical validity|Practical importance of IQ]]'' |
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===Within societies=== |
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====Scope==== |
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The distribution of IQ scores among individuals of each race overlap substantially. In a random sample of equal numbers of US Blacks and Whites, Jensen<ref name="Jensen 1998"/> estimates most variance in IQ would be unrelated to race or social class.<ref>p. 357. Equal-sized random samples of children from California schools were used for this analysis. Social class was rated on a ten-point scale based on parents' education and occupation. Only 30% of total variance in IQ is associated with differences between race and social class, whereas 65% exists within each racial and social class group. The single largest source of IQ variance exists between siblings within the same family.</ref> The average IQ difference between two randomly paired people from the U.S. population is approximately 17 points, and this only increases to 20 points when the pair are black and white. When the pair are siblings, the average difference is still 12 points. |
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In essays accompanying the publication of ''[[The Bell Curve]]'', Herrnstein and Murray argue that whether the cause of the IQ gap is partly genetic (20-80% genetic) or entirely environmental does not really matter because that knowledge alone would not help to eliminate the gap and that knowledge should not impact the way that individuals treat one another. They argue that group differences in intelligence ought not to be treated as more important or threatening than individual differences, but suggest that one legacy of Black slavery has been to exacerbate race relations such that Blacks and Whites cannot be comfortable with group differences in IQ or any other traits.<ref name="The Bell Curve"/><ref name="Murray 2005">{{cite journal | author = Murray, C. | year = 2005 | month = September | title = The Inequality Taboo | journal = Commentary Magazine | volume = 120 | issue = 2 | pages = 13-22 | id = | url = http://www.commentarymagazine.com/production/files/murray0905.html }}</ref> |
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Moreover, although it may appear paradoxical, it could be argued that an indirect outcome of social egalitarianism would be to raise the genetic contribution to intelligence to as high as possible, by minimizing environmental inequalities and any negatively IQ-impacting cultural and socio-economic differences.<ref>''[[The Blank Slate]]'', pp. 106-107.</ref> If all such inequalities could somehow be completely eliminated, any remaining group (but not individual) IQ differences would then be 100% hereditary: the only remaining factor that could potentially contribute to race-based outcome differences. |
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====Practical importance==== |
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The appearance of a large practical importance for intelligence makes some scholars claim that the source and meaning of the IQ gap is a pressing social concern.<ref>{{Cite doi | 10.1037/0003-066x.59.1.7 }}: [http://www2.uni-jena.de/svw/igc/studies/ss03/sackitt_hardison_cullen_2004.pdf] "Sub-group differences in performance on high-stakes tests represent one of American society's most pressing social problems, and mechanisms for reducing or eliminating differences are of enormous interest" (p.11).</ref> The IQ gap is reflected by gaps in the academic, economic, and social factors correlated with IQ.<ref name = "Gordon 1997">{{Cite doi | 10.1016/S0160-2896(97)90017-9}}</ref> <ref name="Gottfredson 1997">{{Cite doi | 10.1016/S0160-2896(97)90014-3}} [http://www.udel.edu/educ/gottfredson/reprints/1997whygmatters.pdf ]</ref> However, some dispute the general importance of the role of IQ for real-world outcomes, especially for differences in accumulated [[wealth]] and general [[economic inequality]] in a nation. (See "[[Intelligence quotient#Practical validity|Practical importance of IQ]]".) |
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The effects of differences in mean IQ between groups (regardless if the cause is social or biological) are amplified by two statistical characteristics of IQ. First, there seem to be minimum statistical thresholds of IQ for many socially valued outcomes (for example, high school graduation and college admission). Second, because of the shape of the [[normal distribution]], only about 16% of the population is at least one standard deviation above the mean. Thus, although the IQ distributions for Blacks and Whites are largely overlapping, different IQ thresholds can have a significant impact on the proportion of Blacks and Whites above and below a particular cut-off. |
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{| class="wikitable" border="1" |
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|+ '''IQ Cohorts & Significance (U.S.)''' |
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|- |
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!IQ range |
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!Whites |
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!Blacks |
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!Black:White ratio |
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!Training prospects |
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!High school dropout |
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!Lives in poverty |
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!"Middle-Class Values" index<ref name="MCV-index">The criteria for the "Middle-Class Values" index were: (for men) obtained high school degree (or more), were in labor force (but could be unemployed) throughout previous year (1989), never incarcerated, were still married to their first wife; (for women) obtained a high school degree, had never given birth out of wedlock, never incarcerated, were still marreid to their first husband. Individuals unable to work and those still in school were excluded from this analysis, as well as never-married individuals who satisfied all the other criteria. Poverty is not a criterion, nor is having children.</ref> |
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|- |
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| <75 || 3.6% || 18.0% || ~5:1 || simple, supervised work; eligible for government assistance || 55% || 30% || 16% |
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|- |
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| 75-90 || 18.3% || 41.4% || ~2:1 || very explicit hands on training; IQ >80 for military training; no government assistance || 35% || 16% || 30% |
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|- |
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| 90-100 || 24.3% || 24.9% || ~1:1 || mastery learning, hands on || rowspan=2 | 6% || rowspan=2 | 6% || rowspan=2 | 50% |
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|- |
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| 100-110 || 25.9% || 11.9% || ~1:2 || written material plus experience |
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|- |
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| 110-125 || 22.5% || 3.6% || ~1:6 || college format || 0.4% || 3% || 67% |
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|- |
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| >125 || 5.4% || 0.2% || ~1:32 || independent, self-teaching || 0% || 2% || 74% |
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|- |
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| colspan="8" | Based on Wechsler Adult Intelligence Scale IQs for Whites (mean = 101.4, SD = 14.7) and for Blacks (mean = 86.9, SD = 13.0) from (Reynolds, Chastain, Kaufman, & McLean, 1987, p. 330). Training prospects from Wonderlic (1992). Significance data is from Herrnstein & Murray (1994)<ref name="The Bell Curve"/>, and is based on Whites only. Results from the total population are nearly indistinguishable. Results for Blacks only are similar but not identical (see the table below for comparisons between groups). Note that these are merely [[correlation]]s. For example, poverty could be both a cause and consequence of low IQ. |
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|} |
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Small differences in IQ, while relatively unimportant at the level of an individual, could theoretically have large effects for the United States population as a whole. As a demonstration of these possible effects, Herrnstein and Murray<ref name="The Bell Curve">{{cite book | last = Hernstein | first = Richard J. | authorlink = | coauthors = Charles Murray | year = 1994 | title = The Bell Curve: Intelligence and Class Structure in American Life | publisher = Free Press | location = New York | id = ISBN 0-02-914673-9}}</ref> used a [[Resampling (statistics)|resampling technique]] to show that, all else equal, a simulated 3-point drop in average IQ had little effect on factors like marriage, divorce, or unemployment. However, a simulated drop in IQ from 100 to 97-points increased poverty rates by 11% and the proportion of children living in poverty by 13%. In the simulation, similar rises occurred in rates of children born to single mothers, men in jail, high school drop-out, and men prevented from working due to health-related problems. In contrast, when they simulated an increase in average IQ of 3-points to 103, they calculated that poverty rates fell 25%, children living in poverty fell 20%, and high school drop-out rates fell 28%.<ref>For this calculation, [[Richard Herrnstein|Herrnstein]] and [[Charles Murray|Murray]] altered the mean IQ (100) of the U.S. [[National Longitudinal Survey|National Longitudinal Survey of Youth]]'s population sample by randomly deleting individuals below an IQ of 103 until the population mean reached 103. Their random deletion procedure was conducted twice and the calculated results were averaged together. Herrnstein and Murray note that their calculation ignore secondary effect. (Herrnstein and Murray 1994, pp. 364-368)</ref> |
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====Controlling for IQ==== |
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{| class="wikitable" border="1" ALIGN="right" |
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|+ '''Group Outcomes After Being Statistically Adjusted to Match IQ''' |
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|- |
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!Condition (matching IQ) |
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!Black % |
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!Latino % |
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!White % |
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|- |
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| High school graduation (103) || 93 || 91 || 89 |
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|- |
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| College graduation (114) || 68 || 49 || 50 |
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|- |
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| High-level occupation (117) || 26|| 16 || 10 |
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|- |
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| Living in poverty (100) || 11 || 9 || 6 |
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|- |
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| Unemployed for 1 month or more (100) || 15 || 11 || 11 |
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|- |
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| Married by age 30 (100) || 58 || 75 || 79 |
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|- |
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| Unwed mother with children (100) || 51 || 17 || 10 |
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|- |
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| Has ever been on welfare (100) || 30 || 15 || 12 |
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|- |
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| Mothers in poverty receiving welfare (100) || 74 || 54 || 56 |
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|- |
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| Having a low birth-weight baby (100) || 6 || 5 || 3 |
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|- |
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| Average annual wage (100) || $25,001 || $25,159 || $25,546 |
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|- |
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| Men ever incarcerated (100) || 5 || 3 || 2 |
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|- |
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| "Middle-Class Values" index<ref name="MCV-index"/> (100) || 32 || 45 || 48 |
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|- |
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| colspan="4" | from Herrnstein & Murray (1994), Chapter 14. |
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|} |
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Because IQ correlates with or predicts a number of social and economic outcomes that have been found to differ between the black and white populations overall, it is possible that some of the disparities in outcomes are due to group differences in IQ. Studies from ''[[The Bell Curve]]'' and elsewhere find that, when IQ is statistically controlled for, the probability of having a college degree or working in a high-IQ occupation is higher for Blacks than Whites. Controlling for IQ shrinks the income gap from thousands to a few hundred dollars. Controlling for IQ cuts differential poverty by about three-quarters and unemployment differences by half. However, controlling for IQ has little effect on differential marriage rates. For many other factors, controlling for IQ eliminates the differences between Whites and Hispanics, but the Black-White gap remains (albeit smaller). |
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Another study found that wealth, race and schooling are important to the inheritance of economic status, but IQ is not a major contributor and the genetic transmission of IQ is even less important.<ref>{{cite journal | author = Bowles, S. and Gintis, H. | year = 2002 | month = Sum | title = The inheritance of inequality | journal = Journal of Economic Perspectives | volume = 16 | issue = 3 | pages = 3-30 | id = | url = http://www.umass.edu/preferen/gintis/intergen.pdf }}. Note that race, schooling and IQ are all correlated, so considering them as separate factors lessens the apparent effect of IQ.</ref> Conversely, controlling for IQ in the above studies also reduces the apparent effect of wealth, race and schooling due to this same correlation. |
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For additional discussion of the effects of controlling for group differences on a variety of outcomes and groups, see Nyborg and Jensen (2001)<ref name="Nyborg and Jensen 2001">{{Cite doi| 10.1016/S0160-2896(00)00042-8}}</ref>, and Kanazawa (2005)<ref name="Kanazawa 2005">{{Cite doi | 10.1016/j.joep.2004.05.001 }}</ref>. |
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===Between nations=== |
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Some people have attributed differential economic growth between nations to differences in the intelligence of their populations. One example is Richard Lynn's ''[[IQ and the Wealth of Nations]]''. The book, is sharply criticized in the peer-reviewed paper ''The Impact of National IQ on Income and Growth''.<ref> Thomas Volken, "[http://www.suz.unizh.ch/volken/ThomasVolken/pdfs/IQWealthNation.pdf The Impact of National IQ on Income and Growth]."</ref> Another peer-reviewed paper, ''Intelligence, Human Capital, and Economic Growth: An Extreme-Bounds Analysis'', finds a strong connection between intelligence and economic growth.<ref>{{cite journal | author = Jones, Garett, and Schneider, Joel W | year = 2005 | month = June | title = Intelligence, Human Capital, and Economic Growth: a Bayesian Averaging of Classical Estimates (BACE) Approach|url = http://www.siue.edu/~garjone/JonesSchneApr.pdf}}</ref> |
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[[Jared Diamond]]'s ''[[Guns, Germs and Steel]]'' instead argues that historical differences in economic and technological development for different areas can be explained by differences in geography (which affects factors like population density and spread of new technology) and differences in available crops and domesticatable animals.<ref>[[Richard E. Nisbett|Richard Nisbett]] argues in his 2004 ''The Geography of Thought'' that some of these regional differences shaped lasting cultural traits, such as the collectivism required by East Asian rice [[irrigation]], compared with the individualism of [[Ancient Greece|ancient Greek]] herding, maritime mercantilism, and money crops wine and olive oil (pp. 34-35).</ref> However, these environmental differences may operate in part by [[natural selection|selecting]] for higher levels of IQ. This theory is discussed by Jensen<ref name="Jensen 1998">{{cite book | author = Jensen, A. R. | authorlink = Arthur Jensen | editor = | others = | title = The ''g'' Factor: The Science of Mental Ability | url = | format = | edition = | year = 1998 | publisher = Praeger Publishers | location = Westport, CT | language = | id = ISBN 0-275-96103-6 | doi = | pages = | chapter = | chapterurl = | quote = }}</ref>, Lynn<ref>{{cite journal | author = Lynn, R. | year = 1991b | month = | title = The Evolution of Racial Differences in Intelligence | journal = Mankind Quarterly | volume = 32 | issue = | pages = 99-173 | id = | url = http://66.102.7.104/search?q=cache:sq.4mg.com/LynnIQdiff.htm }}</ref> and Rushton<ref>{{cite book | author = Rushton, J. P. | authorlink = | coauthors = | year = 2000 | month = | title = Race, Evolution, and Behavior: A Life History Perspective | chapter = | editor = | others = | edition = 3rd | pages = | publisher = Charles Darwin Research Institute | location = Port Huron, MI | id = ISBN 0-9656836-1-3 | url = http://www.charlesdarwinresearch.org/ }}</ref> in general and by both Wade<ref>{{cite book | author = Wade, Nicholas | year = 2006 | title = Before the Dawn: Recovering the Lost History of Our Ancestors | publisher = Penguin Press |location = New York | id = ISBN 1-59420-079-3 }}</ref> and [[Steve Sailer]]<ref>http://www.isteve.com/diamond.htm</ref> with respect to ''Guns, Germs, and Steel''. Voight et al. (2006)<ref>{{Cite doi | 10.1371/journal.pbio.0040072}}</ref> state generally that "a number of recent studies have detected more signals of adaptation in non-African populations than in Africans, and some of those studies have conjectured that non-Africans might have experienced greater pressures to adapt to new environments than Africans have"<ref>{{Cite doi | 10.1093/molbev/msg092}}</ref><ref>{{Cite doi | 10.1371/journal.pbio.0020286}}</ref><ref>{{Cite doi | 10.1093/molbev/msh192}}</ref><ref>{{Cite pmid | 15356276}}</ref><ref>{{Cite pmid | 16251465}}).</ref> |
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===For high-achieving minorities=== |
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The book ''[[World on Fire]]'' notes the existence in many nations of minorities that have created and control a disproportionate share of the economy, a [[market-dominant minority]]. Examples include Chinese in Southeast Asia; Whites, Indians, Lebanese and Igbo people of Western Africa; Whites in Latin America; and Jews in pre-World War II Europe, modern America, and modern Russia. These minorities are often resented and sometimes persecuted by the less successful majority. |
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In the [[United States]], Jews, Asian Indians, Japanese, and Chinese earn incomes 1.72, 1.42, 1.32, and 1.12 times the American average, respectively.<ref>{{cite book | author = Sowell, T. | authorlink = | coauthors = | year = 1981 | month = | title = Ethnic America: A History | chapter = | editor = | others = | edition = | pages = | publisher = | location = | id = ISBN 0-465-02075-5 | url = }}, p. 5</ref> Jews and East Asians have higher rates of college attendance, greater educational attainment, and are many times overrepresented in the [[Ivy League]] and many of the United States' most prestigious schools,<ref>{{cite book | author = Sowell, T. | authorlink = | coauthors = | year = 1981 | month = | title = Ethnic America: A History | chapter = | editor = | others = | edition = | pages = | publisher = | location = | id = ISBN 0-465-02075-5 | url = }}, pp. 7, 93</ref> even though [[affirmative action]] discriminates against Asians in the admissions process (relative to Whites as well as to other minorities)<ref>A study by Princeton researchers {{cite journal | author = Espanshade, T. J., Chung, C. Y. | year = 2005 | month = June | title = The Opportunity Cost of Admission Preferences at Elite Universities | journal = Social Science Quarterly | volume = 86 | issue = 2 | pages = 293-305 | id = | url = http://opr.princeton.edu/faculty/tje/espenshadessqptii.pdf }} analyzes the effects of admission preferences at elite universities in terms of [[SAT]] points (1600-point scale): Blacks +230; Hispanics +185; Asians -50; Recruited athletes +200; [[Legacy preferences|Legacies]] (children of alumni) +160. "Our results show that removing consideration of race would have a minimal effect on white applicants to elite universities. The number of accepted white students would increase by 2.4%." Asian percent of accepted students, in contrast, would increase by 33% (from 23.7% to 31.5%). "Nearly four out of every five places in the admitted class not taken by African-American and Hispanic students would be filled by Asians."</ref> At [[Harvard University|Harvard]], for example, Asian American and Jewish students together make up 51% of the student body, though only constituting roughly 6% of the US population.<ref>{{cite journal | author = Hacker, Andrew | year = 2005 | month = [[November 3]] | title = The Truth About the Colleges | journal = The New York Review of Books | volume = 52 | issue = 17 | url = http://www.nybooks.com/articles/18401 }}</ref> In various [[Southeast Asia]]n nations, Chinese control a majority of the wealth despite being a minority of the population and are resented by the majority, in some cases being the target of violence.<ref>{{cite book | author = Sowell, T. | authorlink = | coauthors = | year = 1981 | month = | title = Ethnic America: A History | chapter = | editor = | others = | edition = | pages = | publisher = | location = | id = ISBN 0-465-02075-5 | url = }}, pp. 133-134</ref><ref>Purdey, J. E., University of Melbourne (2002). http://eprints.unimelb.edu.au/archive/00000840/</ref> |
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Achievement in science, a high-complexity occupation in which practitioners tend to have IQs well above average, also appears consistent with some group IQ disparity.<ref>{{cite journal | author = [http://select.nytimes.com/gst/abstract.html?res=F20B1FFA3E540C7B8CDDAC0894DD404482 Weyl, Nathaniel] | year = 1969 | month = | title = Some comparative performance indexes of American ethnic minorities | journal = Mankind Quarterly | volume = 9 | issue = | pages = 106-128 | doi = | url = }}</ref><ref>{{cite book | author = [http://select.nytimes.com/gst/abstract.html?res=F20B1FFA3E540C7B8CDDAC0894DD404482 Weyl, Nathaniel] | authorlink = | coauthors = | year = 1989 | month = | title = The Geography of American Achievement | chapter = | editor = | others = | edition = | pages = | publisher = Scott-Townsend | location = Washington, D.C. | id = | url = }}, cited by {{cite journal | author = Lynn, R. | year = 1991a | month = | title = Race Differences in Intelligence: A Global Perspective | journal = Mankind Quarterly | volume = 31 | issue = | pages = 255-296 | id = | url = http://www.mugu.com/cgi-bin/Upstream/People/Lynn/lynn-race-iq.html }}.</ref> Only 0.25% of the world population is Jewish, but Jews make up an estimated 28% of [[Nobel prize]] winners in physics, chemistry, medicine, and economics.<ref>jinfo.org (2004). "[http://www.jinfo.org/Nobel_Prizes.html Jewish Nobel Prize Winners]," Accessed December 2005.</ref> In the U.S., these numbers are 2% of the population and 40% of winners. |
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Some studies have shown significant variation in IQ subtest profiles between groups. In one analysis of IQ studies on [[Ashkenazi Jews]], for example, high verbal and mathematical scores, but average or below average visuospatial scores were found.<ref>{{Cite doi | 10.1017/S0021932005027069}}, p. 4</ref> In a separate study, East Asians demonstrated high visuospatial scores, but average or slightly below average verbal scores.<ref>Lynn, [http://www.mugu.com/cgi-bin/Upstream/People/Lynn/lynn-race-iq-table2.html] [http://www.mugu.com/cgi-bin/Upstream/People/Lynn/lynn-race-iq-table2.html]</ref><ref>{{cite book | author = Mackintosh, N. J. | authorlink = | coauthors = | year = 1998 | month = | title = IQ and human intelligence | chapter = | editor = | others = | edition = | pages = | publisher = Oxford University Press | location = Oxford; New York | id = ISBN 0-19-852368-8 | url = }}, p.178)</ref> The professions in which these populations tend to be over-represented differ, and some believe the difference is directly related to IQ subtest score patterns asserted to exist.<ref>{{cite journal | author = Lynn, R. | year = 1991a | month = | title = Race Differences in Intelligence: A Global Perspective | journal = Mankind Quarterly | volume = 31 | issue = | pages = 255-296 | id = | url = http://www.mugu.com/cgi-bin/Upstream/People/Lynn/lynn-race-iq.html }}</ref> The high visiuospatial/average to below average verbal pattern of subtest scores has also been asserted to exist in fully assimilated third-generation Asian Americans, as well as in the [[Inuit]] and [[Indigenous peoples of the Americas|Native Americans]] (both of [[Human migration#Earliest migrations|Asian origin]]).<ref name = "The Bell Curve"/> |
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== Policy implications == |
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{{Main|Intelligence_and_public_policy#Race_issues}} |
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==See also== |
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*[[Height and intelligence]] |
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*[[Hominid intelligence]] |
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*[[Neuroscience and intelligence]] |
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*[[Sex and intelligence]] |
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'''Related publications:''' |
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*''[[The Bell Curve]]'' (1994) |
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*''[[Intelligence: Knowns and Unknowns]]'' (1996) |
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*''[[IQ and Global Inequality]]'' (2006) |
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*''[[The Mismeasure of Man]]'' (1981) |
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*''[[Mainstream Science on Intelligence]]'' (1994; 1997) |
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*''[[Race Differences in Intelligence]]'' (2006) |
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*''[[Snyderman and Rothman (study)|Survey of Expert Opinion on Intelligence and Aptitude Testing]]'' (1987) |
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'''Other medical:''' |
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* [[Ancestry and health]] |
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* [[Population groups in biomedicine]] |
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==References== |
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{{reflist|2}} |
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== External links == |
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=== Collective statements === |
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* [http://www.gifted.uconn.edu/siegle/research/Correlation/Intelligence.pdf APA Task Force Examines the Knowns and Unknowns of Intelligence] |
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* [http://www.aaanet.org/stmts/race.htm Statement on "Race" and Intelligence]. [[American Anthropological Association]]. Adopted December 1994. |
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* [http://www.udel.edu/educ/gottfredson/reprints/1997mainstream.pdf Mainstream Science on Intelligence]. ''Intelligence'', v24 n1 p. 13–23 January–February 1997 |
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=== Review papers === |
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* [http://www.aei.org/events/eventID.1425,filter.all,type.upcoming/event_detail.asp James Flynn and Charles Murray debate] – [http://www.reason.com/news/show/116991.html news summary] |
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* [http://www.udel.edu/educ/gottfredson/30years/ June 2005 issue of ''Psychology, Public Policy, and Law'', Vol. 11, No. 2.] |
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** [http://taxa.epi.umn.edu/~mbmiller/journals/pppl/200504/2/235-2.html Thirty Years of Research on Race Differences in Cognitive Ability] J. Philippe Rushton & Arthur R. Jensen |
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** [http://taxa.epi.umn.edu/~mbmiller/journals/pppl/200504/2/295-2.html There Are No Public-Policy Implications] Robert J. Sternberg |
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** [http://taxa.epi.umn.edu/~mbmiller/journals/pppl/200504/2/311-2.html What if the Hereditarian Hypothesis is True?] Linda S. Gottfredson |
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** [http://taxa.epi.umn.edu/~mbmiller/journals/pppl/200504/2/302-2.html Heredity, Environment, and Race Differences in IQ] Richard E. Nisbett |
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** [http://taxa.epi.umn.edu/~mbmiller/journals/pppl/200504/2/320-2.html The Cultural Malleability of Intelligence and Its Impact on the Racial/Ethnic Hierarchy] Lisa Suzuki & Joshua Aronson |
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** [http://taxa.epi.umn.edu/~mbmiller/journals/pppl/200504/2/328-2.html Wanted: More Race Realism, Less Moralistic Fallacy] J. Philippe Rushton & Arthur R. Jensen |
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* [http://www-personal.umich.edu/~nisbett/racegen.pdf Race, Genetics and IQ] Richard E. Nisbett (PDF) |
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* [http://www.commentarymagazine.com/production/files/murray0905.html The Inequality Taboo] Charles Murray [http://web.archive.org/web/20060515163834/http://www.commentarymagazine.com/production/files/murray0905.html archived version] |
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{{Race and sex differences}} |
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[[Category:Race and intelligence controversy]] |
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[[Category:Anthropology]] |
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[[Category:Eugenics]] |
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[[Category:Intelligence]] |
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[[Category:Population genetics]] |
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[[Category:Psychology]] |
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[[Category:Race]] |
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[[Category:Scientific controversies]] |
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[[Category:Scientific racism]] |
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[[pl:Rasa a inteligencja]] |
[[pl:Rasa a inteligencja]] |
Revision as of 06:36, 20 January 2010
Race and intelligence can refer to issues raised in:
- Scholarly literature about the existence and causes of suspected differences in intelligence across different genetic and social groups.
- The study of genetic heritability of intelligence for individuals.
- Debates concerning the meaning of Race in studies of intelligence.
- Public policy issues affected by intelligence research.