Editing Intelligence quotient (section)

==Group differences==
Among the most controversial issues related to the study of intelligence is the observation that IQ scores vary on average between ethnic and racial groups, though these differences have fluctuated and in many cases steadily decreased over time.<ref name=":8">{{Cite journal |last1=Nisbett |first1=Richard E. |last2=Aronson |first2=Joshua |last3=Blair |first3=Clancy |last4=Dickens |first4=William |last5=Flynn |first5=James |last6=Halpern |first6=Diane F. |last7=Turkheimer |first7=Eric |date=2012 |title=Intelligence: New findings and theoretical developments |journal=American Psychologist |volume=67 |issue=2 |pages=130–159 |doi=10.1037/a0026699 |issn=1935-990X |pmid=22233090}}</ref> While there is little scholarly debate about the continued existence of some of these differences, the current scientific consensus is that they stem from environmental rather than genetic causes.{{sfn|Ceci|Williams|2009|pages=788–789, "There is an emerging consensus about racial and gender equality in genetic determinants of intelligence; most researchers, including ourselves, agree that genes do not explain between-group differences"}}<ref name=":9">{{Cite journal |date=25 May 2017 |title=Intelligence research should not be held back by its past |journal=Nature |volume=545 |issue=7655 |pages=385–386 |doi=10.1038/nature.2017.22021 |pmid=28541341 |bibcode=2017Natur.545R.385. |s2cid=4449918 |quote=Intelligence science has undoubtedly been dogged by ugly prejudice. Historical measurements of skull volume and brain weight were done to advance claims of the racial superiority of white people. More recently, the (genuine but closing) gap between the average IQ scores of groups of black and white people in the United States has been falsely attributed to genetic differences between the races.|doi-access=free }}</ref><ref name=":03" /> The existence of differences in IQ between the sexes has been debated, and largely depends on which tests are performed.<ref name="Mackintosh2">{{harvnb|Mackintosh|2011|pp=[https://books.google.com/books?id=BcKcAQAAQBAJ&pg=PA362 362–363]}}</ref><ref name="Hunt 389">{{harvnb|Hunt|2011|p=[https://books.google.com/books?id=DwO4TtKAiCoC&pg=PA389 389]}}</ref>

===Race===
{{Main|Race and intelligence}}While the concept of "[[Race (human categorization)|race]]" is a [[social construct]],<ref name=":82">{{Cite book |url=https://nap.nationalacademies.org/read/26902/chapter/1 |title=Using Population Descriptors in Genetics and Genomics Research: A New Framework for an Evolving Field (Consensus Study Report) |date=2023 |publisher=[[National Academies of Sciences, Engineering, and Medicine]] |isbn=978-0-309-70065-8 |doi=10.17226/26902 |pmid=36989389 |quote=In humans, race is a socially constructed designation, a misleading and harmful surrogate for population genetic differences, and has a long history of being incorrectly identified as the major genetic reason for phenotypic differences between groups.}}</ref> discussions of a purported relationship between race and intelligence, as well as claims of genetic differences in intelligence along racial lines, have appeared in both [[popular science]] and [[academic research]] since the modern concept of race was first introduced.

Genetics do not explain differences in IQ test performance between racial or ethnic groups.<ref name=":12"/>{{sfn|Ceci|Williams|2009|pages=788–789, "There is an emerging consensus about racial and gender equality in genetic determinants of intelligence; most researchers, including ourselves, agree that genes do not explain between-group differences"}}<ref name=":9" /><ref name=":03" /> Despite the tremendous amount of research done on the topic, no scientific evidence has emerged that the average IQ scores of different population groups can be attributed to genetic differences between those groups.<ref>{{Cite book |last1=Jencks |first1=Christopher |author-link=Christopher Jencks |title=The Black-White Test Score Gap |last2=Phillips |first2=Meredith |publisher=Brookings Institution Press |year=2011 |isbn=9780815746119 |pages=503 |quote=The available evidence reviewed by several authors in this volume provides, as Richard E. Nisbett puts it, 'no evidence for genetic superiority of either race while providing strong evidence for a substantial environmental contribution to the black-white IQ gap.' |orig-date=1998}}</ref><ref name=":10">{{Cite web |last1=Birney |first1=Ewan |author-link=Ewan Birney |last2=Raff |first2=Jennifer |author-link2=Jennifer Raff |last3=Rutherford |first3=Adam |author-link3=Adam Rutherford |last4=Scally |first4=Aylwyn |date=24 October 2019 |title=Race, genetics and pseudoscience: an explainer |url=http://ewanbirney.com/2019/10/race-genetics-and-pseudoscience-an-explainer.html |website=Ewan's Blog: Bioinformatician at large |quote=‘Human biodiversity’ proponents sometimes assert that alleged differences in the mean value of IQ when measured in different populations – such as the claim that IQ in some sub-Saharan African countries is measurably lower than in European countries – are caused by genetic variation, and thus are inherent. . . . Such tales, and the claims about the genetic basis for population differences, are not scientifically supported. In reality for most traits, including IQ, it is not only unclear that genetic variation explains differences between populations, it is also unlikely.}}</ref><ref>{{Cite journal |last1=Aaron |first1=Panofsky |author-link=Aaron Panofsky |last2=Dasgupta |first2=Kushan |date=28 September 2020 |title=How White nationalists mobilize genetics: From genetic ancestry and human biodiversity to counterscience and metapolitics |journal=American Journal of Biological Anthropology |volume=175 |issue=2 |pages=387–398 |doi=10.1002/ajpa.24150 |pmc=9909835 |pmid=32986847 |s2cid=222163480 |quote=[T]he claims that genetics defines racial groups and makes them different, that IQ and cultural differences among racial groups are caused by genes, and that racial inequalities within and between nations are the inevitable outcome of long evolutionary processes are neither new nor supported by science (either old or new).}}</ref> In recent decades, as understanding of [[Human genome|human genetics]] has advanced, claims of inherent differences in intelligence between races have been broadly rejected by scientists on both [[Theory|theoretical]] and [[Empirical evidence|empirical]] grounds.<ref name=":322" /><ref name=":03" /><ref name=":02">{{Cite news |last=Mitchell |first=Kevin |date=2 May 2018 |title=Why genetic IQ differences between 'races' are unlikely: The idea that intelligence can differ between populations has made headlines again, but the rules of evolution make it implausible |url=https://www.theguardian.com/science/blog/2018/may/02/why-genetic-iq-differences-between-races-are-unlikely |access-date=13 June 2020 |work=The Guardian}}</ref><ref name=":2" /><ref name=":10" />

Growing evidence indicates that environmental factors, not genetic ones, explain the racial IQ gap.<ref name=":2">{{Cite journal |last=Kaplan |first=Jonathan Michael |date=January 2015 |title=Race, IQ, and the search for statistical signals associated with so-called "X"-factors: environments, racism, and the "hereditarian hypothesis" |journal=Biology & Philosophy |volume=30 |issue=1 |pages=1–17 |doi=10.1007/s10539-014-9428-0 |issn=0169-3867 |s2cid=85351431}}</ref><ref name=":322">{{Cite journal|last1=Dickens|first1=William T.|last2=Flynn|first2=James R.|date=2006|title=Black Americans Reduce the Racial IQ Gap: Evidence from Standardization Samples|url=http://www.iapsych.com/iqmr/fe/LinkedDocuments/dickens2006a.pdf|journal=Psychological Science|volume=17|issue=10|pages=913–920|doi=10.1111/j.1467-9280.2006.01802.x|pmid=17100793|s2cid=6593169}}</ref><ref name=":03">{{cite journal|last1=Nisbett|first1=Richard E.|last2=Aronson|first2=Joshua|last3=Blair|first3=Clancy|last4=Dickens|first4=William|last5=Flynn|first5=James|author-link5=Jim Flynn (academic)|last6=Halpern|first6=Diane F.|author-link6=Diane F. Halpern|last7=Turkheimer|first7=Eric|date=2012|title=Group differences in IQ are best understood as environmental in origin|url=http://people.virginia.edu/~ent3c/papers2/Articles%20for%20Online%20CV/Nisbett%20(2012)%20Group.pdf|journal=American Psychologist|volume=67|pages=503–504|doi=10.1037/a0029772|issn=0003-066X|pmid=22963427|access-date=22 July 2013|number=6|author-link1=Richard E. Nisbett}}</ref> A 1996 task force investigation on intelligence sponsored by the [[American Psychological Association]] concluded that "because ethnic differences in intelligence reflect complex patterns, no overall generalization about them is appropriate," with environmental factors the most plausible reason for the shrinking gap.{{sfn|Neisser et al.|1995}} A systematic analysis by [[William Dickens]] and [[James Flynn (academic)|James Flynn]] (2006) showed the gap between black and white Americans to have closed dramatically during the period between 1972 and 2002, suggesting that, in their words, the "constancy of the Black–White IQ gap is a myth".<ref name=":32">{{Cite journal|last1=Dickens|first1=William T.|last2=Flynn|first2=James R.|date=2006|title=Black Americans Reduce the Racial IQ Gap: Evidence from Standardization Samples |url=http://www.iapsych.com/iqmr/fe/LinkedDocuments/dickens2006a.pdf|journal=Psychological Science |volume=17|issue=10|pages=913–920|doi=10.1111/j.1467-9280.2006.01802.x|pmid=17100793|s2cid=6593169}}</ref> The effects of [[stereotype threat]] have been proposed as an explanation for differences in IQ test performance between racial groups,{{sfn|Mackintosh|2011|p=348}}<ref>{{cite book |last1=Inzlicht |first1=Michael |title=Stereotype Threat: Theory, Process, and Application |date=2011 |publisher=Oxford University Press |isbn=978-0199732449 |pages=5, 141–143}}</ref> as have issues related to cultural difference and access to education.<ref>{{Cite book |last1=Shuttleworth-Edwards |first1=Ann B. |title=Minority and cross-cultural aspects of neuropsychological assessment |last2=Van der Merwe |first2=Adele S. |publisher=Swets & Zeitlinger |year=2002 |isbn=9026518307 |editor-last=Ferraro |editor-first=F. Richard |location=Exton, PA |pages=72–75 |chapter=WAIS-III and WISC-IV South African Cross-Cultural Normative Data Stratified for Quality of Education}}</ref><ref name=":6">Barbara P. Uzzell, Marcel Ponton, Alfredo Ardila International Handbook of Cross-Cultural Neuropsychology book {{ISBN|978-0805835854}} (2013)</ref>

Despite the strong scientific consensus to the contrary, fringe figures continue to promote [[scientific racism]] about group-level IQ averages in [[pseudo-scholarship]] and popular culture.<ref name=":12" /><ref name=":13" /><ref name=":11" />

===Sex===
{{Main|Sex differences in intelligence}}

With the advent of the concept of ''g'' or [[general intelligence]], many researchers have found that there are no significant sex differences in average IQ,<ref name="Hunt 389"/><ref name="Plotnik2">{{cite book |url=https://books.google.com/books?id=6jLTCQAAQBAJ&pg=PT324|title=Introduction to Psychology |vauthors=Plotnik R, Kouyoumdjian H|publisher=[[Cengage Learning]]|year=2013|isbn=978-1133939535|pages=282–283}}</ref><ref name="Hunt 378-379">{{harvnb|Hunt|2011|pp=[https://books.google.com/books?id=DwO4TtKAiCoC&pg=PA378 378–379]}}</ref> though ability in particular types of intelligence does vary.<ref name="Mackintosh2"/><ref name="Hunt 378-379"/> Thus, while some test batteries show slightly greater intelligence in males, others show greater intelligence in females.<ref name="Mackintosh2"/><ref name="Hunt 378-379"/> In particular, studies have shown female subjects performing better on tasks related to [[Linguistic intelligence|verbal ability]],<ref name="Hunt 389"/> and males performing better on tasks related to rotation of objects in space, often categorized as [[spatial ability]].<ref name="Terry2">{{cite book |url=https://books.google.com/books?id=4s5WCgAAQBAJ&pg=PA356|title=Learning and Memory: Basic Principles, Processes, and Procedures, Fourth Edition|vauthors=Terry WS|publisher=[[Psychology Press]] |year=2015|isbn=978-1317350873 |page=356}}</ref> These differences remain, as {{harvp|Hunt|2011}} observes, "even though men and women are essentially equal in general intelligence".

Some research indicates that male advantages on some [[cognitive test]]s are minimized when controlling for socioeconomic factors.<ref name="Mackintosh2"/><ref name="Plotnik2"/> Other research has concluded that there is slightly [[Variability hypothesis|larger variability]] in male scores in certain areas compared to female scores, which results in slightly more males than females in the [[Intellectual giftedness|top]] and [[Intellectual disability|bottom]] of the IQ distribution.<ref name="Chrisler JC">{{cite book|url= https://books.google.com/books?id=Xtq0M1f_aIMC&pg=PA302 |title=Handbook of Gender Research in Psychology: Volume 1: Gender Research in General and Experimental Psychology |vauthors=Chrisler JC, McCreary DR |publisher=[[Springer Science & Business Media]] |year=2010 |isbn=978-1441914651|page=302}}</ref>

The existence of differences between male and female performance on math-related tests is contested,<ref name=":5">{{cite journal|last1=Hyde|first1=J. S.|last2=Linn|first2=M. C.|date=27 October 2006 |title=DIVERSITY: Enhanced: Gender Similarities in Mathematics and Science|journal=Science|volume=314 |issue=5799 |pages=599–600|doi=10.1126/science.1132154|pmid=17068246|s2cid=34045261}}</ref> and a meta-analysis focusing on average gender differences in math performance found nearly identical performance for boys and girls.<ref>{{cite journal|last1=Hyde|first1=Janet S.|last2=Fennema|first2=Elizabeth|last3=Lamon|first3=Susan J.|date=1990|title=Gender differences in mathematics performance: A meta-analysis.|journal=Psychological Bulletin|volume=107|issue=2|pages=139–155|doi=10.1037/0033-2909.107.2.139|pmid=2138794}}</ref> Currently, most IQ tests, including popular batteries such as the WAIS and the WISC-R, are constructed so that there are no overall score differences between females and males.{{sfn|Neisser et al.|1995}}<ref name="apa">{{cite journal |last1=Nisbett |first1=Richard E. |last2=Aronson |first2=Joshua |last3=Blair |first3=Clancy |last4=Dickens |first4=William |last5=Flynn |first5=James |last6=Halpern |first6=Diane F. |last7=Turkheimer |first7=Eric |title=Intelligence: New findings and theoretical developments. |journal=American Psychologist |date=2012 |volume=67 |issue=2 |pages=130–159 |doi=10.1037/a0026699 |pmid=22233090 |s2cid=7001642}}</ref>{{sfn|Jensen|1998|p=531}}