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Racial differences in IQ scores are observed around the world.<ref name ="Lynn Vanhanen"/><ref name ="Lynn 2006"/> 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="Lynn Vanhanen">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> The very low IQ scores reported for sub-Saharan African populations are especially controversial.<ref>{{Cite doi|10.1016/j.intell.2009.05.002}}</ref><ref>{{Cite doi|10.1016/j.intell.2009.09.009}}</ref><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>
Racial differences in IQ scores are observed around the world.<ref name ="Lynn Vanhanen"/><ref name ="Lynn 2006"/> Lynn's meta-analysis lists [[East Asia]]ns (105), [[European ethnic groups|Europeans]] (102), [[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="Lynn Vanhanen">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> The very low IQ scores reported for sub-Saharan African populations are especially controversial.<ref>{{Cite doi|10.1016/j.intell.2009.05.002}}</ref><ref>{{Cite doi|10.1016/j.intell.2009.09.009}}</ref><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>


====Flynn effect====
====Flynn effect====

Revision as of 17:22, 4 April 2010

Race and intelligence involves debate over the genetic links, if any, between race and intelligence. This research is grounded in two controversial assumptions:

IQ tests show significantly different average scores in different races,[1] with commonly accepted racial averages of 106 for East Asians, 100 for whites and 85 for African Americans.[2] Some scholars regard the topic as scientifically meaningless because race and/or intelligence are suspect constructs.[3] Others dispute whether it is possible to scientifically address the question in a way that is ethical.[4] Other scientists reject both of these positions, arguing instead that the social implications are too important to forego research.[5] The scientific consensus holds that environmental factors cause at least part of the average IQ differences between races.[1] The primary focus of the debate is over whether or not genetic factors explain a portion of the difference in average group IQs.

History

The idea that there are differences in the brain structures/sizes of different racial groups, and that these differences explain varying rates of intelligence, was widely held and studied during the 19th and early 20th centuries.[6][7][8] Francis Galton spurred interest in the study of mental abilities, particularly as they relate to heredity and eugenics. Beginning in the 1930s, race difference research and hereditarianism—the belief that genetics are an important cause of differences in intelligence among human groups—began to fall out of favor in psychology and anthropology after major internal debates.

Group differences in measures of intelligence

Main article: Heritability of IQ

There is a consensus among intelligence researchers that IQ, like height, within the same population is significantly heritable.[1][9][10][11][12][13][14]

Data gathering methods

Main article: Intelligence
Further information: [[:intelligence quotient, general intelligence factor]]

Intelligence is most commonly measured using IQ tests. These tests are often geared to measure the psychometric variable g (for general intelligence factor). Other tests that measure g (for example, the Armed Forces Qualifying Test and the SAT) also serve as measures of cognitive ability.

All such tests are often called "intelligence tests," though the use of the term "intelligence" is itself controversial. It is clear, however, that performance in these tests correlates with performance in similar life tasks (school grades and to a lower degree college grades). The correlation with many real-world results is lower. For example, while the correlation of IQ with job performance is strong, income is modestly correlated and accumulated wealth is only weakly correlated. As commonly used, "IQ test" denotes any test of cognitive ability, and "IQ" is used as shorthand for scores on tests of cognitive ability. Several conclusions about tests of cognitive ability are now largely accepted:[1]

  • IQ scores measure many, but not all of the qualities that people mean by intelligent or smart (for example, IQ does not measure creativity, wisdom, or personality).
  • IQ scores are fairly stable over much of a person's life.
  • IQ tests are predictive of school and job performance, to a degree that does not significantly vary by socio-economic or racial-ethnic background.
  • For people living in the prevailing conditions of the developed world, cognitive ability is substantially heritable, and while the impact of family environment on the IQ of children is substantial, after adolescence this effect becomes difficult to detect.

Intelligence test score results

Most of the evidence of intelligence differences between racial groups is based on studies of IQ 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.

There is a consensus that test score differences between blacks and whites in the United States have predictive validity, meaning that test scores predict the same socially-relevant outcomes regardless of the race of the person being tested. Black-White differences in IQ test scores are not a result of measurement bias.[15][16]

United States

There are observed differences in average test score achievement between racial 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.[17] According to James Flynn and others, the overall average Black-White gap has reduced by one third over the course of the 20th century.[17] 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.[18] This improvement is also reflected in Black-White differences on 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.[19]

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 between individual differences in IQ test performance.[20] Gaps are seen in other tests of cognitive ability or aptitude, including university admission exams such as the SAT and GRE as well as employment tests for corporate settings and the military.[21]

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,[22][23] tend to score worse on average than White populations but better on average than Black populations.[21] East Asian populations may score higher on average than White populations in the United States as they do elsewhere.[24]

Worldwide

Racial differences in IQ scores are observed around the world.[25][26] Lynn's meta-analysis lists East Asians (105), Europeans (102), Inuit (91), Southeast Asians and Amerindians (87 each), Pacific Islanders (85), South Asians/North Africans (84), Non-Bushmen sub-Saharan Africans (67), Australian Aborigines (62) and Bushmen (54).[27][28][26][29][25] International achievement test scores, including TIMSS and PISA, have also been used to estimate average IQ worldwide with similar results where data is available.[30][31][32] The very low IQ scores reported for sub-Saharan African populations are especially controversial.[33][34][35]

Flynn effect

Main article: Flynn effect

The Flynn effect describes an increase in the average intelligence quotient (IQ) test scores over generations (IQ gains over time). Similar improvements have been reported for other cognitions such as semantic and episodic memory.[36] The effect has been observed in most parts of the world at different rates. The Flynn effect is named for James R. Flynn, who did much to document it and promote awareness of its implications. The effect increase has been continuous and approximately linear from the earliest years of testing to the present.

Variables potentially affecting intelligence in groups

Many factors, both genetic and environmental, influence the intelligence of individuals. To the extent that racial groups are exposed to these factors to different degrees, average IQs by race will differ as a result of these correlations.

Health and Nutrition

Main article: Health and intelligence

Factors including lead exposure,[37] iodine deficiency,[38] breast feeding,[39] and nutrition[40][41] can significantly affect cognitive development and functioning. Such impairment may sometimes be permanent, sometimes be partially or wholly compensated for by later growth. Comprehensive policy recommendations targeting reduction of cognitive impairment in children have been proposed.[42]

Rearing conditions

The Minnesota Transracial Adoption Study examined the IQ test scores of 130 black/interracial children adopted by advantaged white families.[43][44][45] The aim of the study was to determine the contribution of genetic factors to the poor performance of black children on IQ tests as compared to white children. The following table provides a summary of the results.[46]

Children's background Age 7 Corrected IQ Age 17 Corrected IQ
Non adopted, with two white biological parents 110.5 105.5
Adopted, with two white biological parents 111.5 101.5
Adopted, with one white and one black biological parent 105.4 93.2
Adopted, with two black biological parents 91.4 83.7

Socioeconomic environment

File:TBC-BW-IQ-SES-withDiff.png
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.[47]

Education

See also: Environment and intelligence

Education has a complicated relationship with intelligence; it is both a dependent and independent variable.[1] On the one hand, those who did better on intelligence tests in their childhood tend to have a lower drop out rate, and complete more years of school, therefore making intelligence a predictive factor of how well someone will succeed in schooling.[1] However, on the other hand, education has been shown to improve a person’s performance on these intelligence tests, from a very young age.[1]

Discrimination

Main article: Discrimination

Discrimination is a sociological term referring to the treatment taken toward or against a person of a certain group in consideration based solely on class or category. Discrimination is the actual behavior towards another group. It involves excluding or restricting members of one group from opportunities that are available to other groups. A student's race can influence teachers' referral decisions for gifted and talented educational programs.[48]

Stereotypical behaviour

Main article: Stereotype threat

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.[49] 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.

Geographic ancestry

African Americans typically have ancestors from both Africa and Europe, with, on average, 20% of their genome inherited from European ancestors.[50] Several studies performed without the use of DNA-based ancestry estimation attempted to correlate 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 sample sizes.

Physiology

Within human population, studies have been conducted to determine whether there is a relationship between brain size and a number of cognitive measures. Studies have reported correlations that range from 0 to 0.6, with most correlations 0.3 or 0.4.[51]

A study on twins showed that frontal gray matter volume was correlated with g and highly heritable.[52] A related study has reported that the correlation between brain size (reported to have a heritability of 0.85) and g is 0.4, and that correlation is mediated entirely by genetic factors.Posthuma; et al. (2002). "The association between brain volume and intelligence is of genetic origin". Nature Neuroscience. 5: 83–84. {{cite journal}}: Explicit use of et al. in: |author= (help); line feed character in |title= at position 30 (help)

In a study of the head growth of 633 term-born children from the Avon Longitudinal Study of Parents and Children cohort, it was shown that prenatal growth and growth during infancy were associated with subsequent IQ. The study’s conclusion was that the brain volume a child achieves by the age of 1 year helps determine later intelligence.[53]

Neuropsychology

Genetics

Two 2007 studies found that DTNBP1 and CHRM2 appear to influence intelligence depending on which allele of it a person carries.[54][55] Other researchers have challenged those results.[56]

Significance of group IQ differences

Interpretations

Publication in 1969 of Arthur Jensen's controversial article, "How Much Can We Boost IQ and School Achievement?"[57] triggered the modern debate. In it, he wrote

So all we are left with are various lines of evidence, no one of which is definitive alone, but which, viewed all together, make it a not unreasonable hypothesis that genetic factors are strongly implicated in the average Negro-white intelligence difference. The preponderance of the 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.

Many authors disputed Jensen's conclusions, most prominently Stephen Jay Gould in The Mismeasure of Man, originally published in 1981.[58]

Richard Herrnstein and Charles Murray wrote in The Bell Curve: "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."

The American Anthropological Association argues that "differentiating species into biologically defined "races" has proven meaningless and unscientific as a way of explaining variation (whether in intelligence or other traits)."[59]

The American Psychological Association's Board of Scientific Affairs in 1995 established a task force which produced a report, "Intelligence: Knowns and Unknowns"[1] 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). The APA report confirmed the existence of racial IQ differences, while remaining agnostic about their underlying causes:

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.[1]

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. Many scientists took issue with various aspects of the report.[60]

Environmental interpretations

Proponents of the environmental interpretation argue that genetics explain none of the differences in measured intelligence among human races. Leading scholars of this view include Richard Lewontin, Stephen J. Gould, James Flynn, Robert Nisbett and Stephen Ceci.

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 0.1 (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."[61] Hunt and Carlson[62] argue that Nisbett's interpretations are far too strong in light of problems with these studies that have been recognized for decades.[63] Gottfredson writes that the studies Nisbett cites "actually lack the ability to rule out any hypothesis at all, genetic or not".[64]

An environmental factor that varies between groups but not within groups can cause group differences in a trait that is otherwise 100% heritable. The height of this "ordinary genetically varied corn" is 100% heritable, but the difference between the group averages is completely environmental. This is because the nutrient solution varies between populations, but not within populations.

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.[65] David Layzer (1974) contends that the development of a trait can be influenced by genetic differences qualitatively 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.[66]

The alternative to common environmental factors is the hypothesis 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 is 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.

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 three points per decade during the 20th century, which he and others attribute predominantly to environmental causes.[67] This means, given the same test, the mean performance of African Americans today could be higher than the mean for white Americans in 1920, though the gains causing this appear to have occurred predominantly in the lower half of the IQ distribution.[68] 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.

Nichols (1987)[69] critically summarized the argument as follows:

(1) We do not know what causes the test score changes over time. (2) We do not know what causes racial differences in intelligence. (3) Since both causes are unknown, they must, therefore, be the same. (4) Since the unknown cause of changes over time cannot be shown to be genetic, it must be environmental. (5) Therefore, racial differences in intelligence are environmental in origin.

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."[70]

Hereditarian interpretations

Hereditarians argue that genetics explain a significant portion (approximately half) of the differences in measured intelligence among human races. Leading scholars of this view include Arthur Jensen, Hans Eysenck, Philippe Rushton, Richard Herrnstein, Linda Gottfredson, Charles Murray, Raymond Cattell, and Richard Lynn.

Rushton and 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.[71][72] 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.[73]

However, some psychometricians are not satisfied that the question of test bias is fully answered by these results.[74]

Jensen and Rushton have justified their research in this area as being necessary to answer the question of how much white racism should be held responsible for ethnic groups' unequal performance in certain areas. They maintain that when racism is blamed for disparities which are the result of biological differences, the result is mutual resentment, and unjustified punishment of the more successful group. They state:

[T]he view that one segment of the population is largely to blame for the problems of another segment can be even more harmful to racial harmony, by first producing demands for compensation and thereby inviting a backlash. Equating group disparities in success with racism on the part of the more successful group guarantees mutual resentment. As overt discrimination fades, still large racial disparities in success lead blacks to conclude that white racism is not only pervasive but also insidious because it is so unobservable and "unconscious." Whites resent that nonfalsifiable accusation and the demands to compensate blacks for harm they do not believe they caused.[2]

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,[75] 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.[76]

See also

Notes

  1. ^ a b c d e f g h i Neisser, U., Boodoo, G., Bouchard, T. J. Jr., Boykin, A. W., Brody, N., Ceci, S. J.; et al. (1996). "Intelligence: Knowns and unknowns" (PDF). American Psychologist. 51: 77–101. {{cite journal}}: Explicit use of et al. in: |author= (help)CS1 maint: multiple names: authors list (link)
  2. ^ a b J. Philippe Rushton and Arthur Jensen (2005). "Thirty Years of Research on Race Differences in Cognitive Ability" (PDF). Psychology, Public Policy, and Law. 11 (2): 235–294. doi:10.1037/1076-8971.11.2.235.
  3. ^ Sternberg, R.; Grigorenko, E.; Kidd, K. (2005). "Intelligence, race, and genetics" (PDF). The American psychologist. 60 (1): 46–59. doi:10.1037/0003-066X.60.1.46. PMID 15641921. {{cite journal}}: More than one of |author2= and |last2= specified (help); More than one of |author3= and |last3= specified (help)}}
  4. ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1038/457786a, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1038/457786a instead.
  5. ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1038/457788a, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1038/457788a instead.
  6. ^ Samuel George Morton (1839). Crania Americana; or, A Comparative View of the Skulls of Various Aboriginal Nations of North and South America: To which is Prefixed An Essay on the Varieties of the Human Species. J. Dobson. {{cite book}}: Unknown parameter |city= ignored (|location= suggested) (help)
  7. ^ Robert Bennett Bean (1906). "Some racial peculiarities of the Negro brain". American Journal of Anatomy. 5: 353–432. doi:10.1002/aja.1000050402.
  8. ^ F. P. Mall (1909). "On several anatomical characters of the human brain, said to vary according to race and sex, with especial reference to the weight of the frontal lobe". American Journal of Anatomy. 9: 1–32.
  9. ^ R. J. Sternberg (2000) Handbook of Intelligence. Cambridge: Cambridge University Press
  10. ^ David J. Bartholomew (2004) Measuring Intelligence: Facts and Fallacies. Cambridge: Cambridge University Press
  11. ^ Ian J. Deary. (2001) Intelligence: A Very Short Introduction. Oxford: Oxford University Press
  12. ^ Gottfredson, L. S. (1997). Mainstream science on intelligence: An editorial with 52 signatories, history, and bibliography. Intelligence, 24(1), 13–23.
  13. ^ Robert Plomin, John C. DeFries, Gerald E. McClearn, and Peter McGuffin (2000) Behavioral Genetics. Worth Publishers; Fourth Edition edition
  14. ^ Brody, N. (1992). Intelligence (2nd ed.). San Diego, CA: Academic Press.
  15. ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1207/S15327906MBR3501_2, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1207/S15327906MBR3501_2 instead.
  16. ^ Dolan, C. V. and Hamaker, E. L. (2001). "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". In F. Columbus (ed.). Advances in Psychological Research (PDF). Huntington, NY: Nova Science Publishers, Inc. ISBN 1-56072-897-3. {{cite book}}: Cite has empty unknown parameters: |coauthors= and |month= (help)CS1 maint: multiple names: authors list (link)
  17. ^ a b James R. Flynn, The Black-White IQ Gap
  18. ^ Loehlin, J. C., Lindzey, G., & Spuhler, J. N. (1975). Race differences in intelligence. San Francisco, CA: W.H. Freeman.
  19. ^ Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi:10.1016/j.intell.2006.07.004, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi=10.1016/j.intell.2006.07.004 instead.
  20. ^ Jensen, Arthur (1998). The g Factor: The Science of Mental Ability. Westport, CT: Praeger Publishers. ISBN 0-275-96103-6.
  21. ^ a b Attention: This template ({{cite doi}}) is deprecated. To cite the publication identified by doi: 10.1111/j.1744-6570.2001.tb00094.x, please use {{cite journal}} (if it was published in a bona fide academic journal, otherwise {{cite report}} with |doi= 10.1111/j.1744-6570.2001.tb00094.x instead.
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References

Main article: Race and intelligence (References)


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