Editing Intelligence (section)

=== Intelligence quotient (IQ) ===
{{Main|Intelligence quotient}}

There have been various attempts to quantify intelligence via [[psychometric]] testing. Prominent among these are the various [[Intelligence quotient|Intelligence Quotient]] (IQ) tests, which were first developed in the early 20th century to screen children for [[intellectual disability]].<ref name=":6">{{Cite book |last=Kaufman |first=Alan S. |title=IQ Testing 101 |publisher=Springer |year=2009 |isbn=978-0-8261-0629-2}}</ref> Over time, IQ tests became more pervasive, being used to screen immigrants, military recruits, and job applicants.<ref>{{cite journal |last1=Richardson |first1=John T. E. |year=2003 |title=Howard Andrew Knox and the origins of performance testing on Ellis Island, 1912-1916 |journal=History of Psychology |volume=6 |issue=2 |pages=143–70 |doi=10.1037/1093-4510.6.2.143 |pmid=12822554}}</ref> As the tests became more popular, belief that IQ tests measure a fundamental and unchanging attribute that all humans possess became widespread.<ref name=":6" /> 

An influential theory that promoted the idea that IQ measures a fundamental quality possessed by every person is the theory of [[G factor (psychometrics)|General Intelligence, or ''g'' factor]].<ref>{{Cite journal |last=Schlinger |first=Henry D. |date=2003 |title=The myth of intelligence |url=https://psycnet.apa.org/record/2003-01443-003 |journal=The Psychological Record |volume=53 |issue=1 |pages=15–32}}</ref> The ''g'' factor is a construct that summarizes the [[Correlation|correlations]] observed between an individual's scores on a range of cognitive tests. 

Today, most psychologists agree that IQ measures at least some aspects of human intelligence, particularly the ability to thrive in an academic context.<ref name="Weiten" /> However, many psychologists question the [[Validity (statistics)|validity]] of IQ tests as a measure of intelligence as a whole.<ref name="Weiten">{{cite book |url=https://books.google.com/books?id=ALkaCgAAQBAJ&pg=PT331 |title=Psychology: Themes and Variations |vauthors=Weiten W |publisher=[[Cengage Learning]] |year=2016 |isbn=978-1305856127 |page=281 |quote=IQ tests are valid measures of the kind of intelligence necessary to do well in academic work. But if the purpose is to assess intelligence in a broader sense, the validity of IQ tests is questionable.}}</ref><ref name=":4">{{Cite journal|last=Bouchard|first=Thomas J.|date=1982|title=Review of The Intelligence Controversy|url=https://www.jstor.org/stable/1422481|journal=The American Journal of Psychology|volume=95|issue=2|pages=346–349|doi=10.2307/1422481|jstor=1422481|issn=0002-9556|url-access=subscription}}</ref>

There is debate about the [[heritability of IQ]], that is, what proportion of differences in IQ test performance between individuals are explained by [[Genetics|genetic]] or [[Biophysical environment|environmental]] factors.<ref name="Bouchard2013W">{{cite journal|last1=Bouchard|first1=Thomas J.|date=7 August 2013|title=The Wilson Effect: The Increase in Heritability of IQ With Age|journal=Twin Research and Human Genetics|volume=16|issue=5|pages=923–930|doi=10.1017/thg.2013.54|pmid=23919982|s2cid=13747480|doi-access=free}}</ref><ref name="pmid12486697">{{cite journal |last1=Bouchard |first1=Thomas J. |last2=McGue |first2=Matt |title=Genetic and environmental influences on human psychological differences |journal=Journal of Neurobiology |date=January 2003 |volume=54 |issue=1 |pages=4–45 |doi=10.1002/neu.10160 |pmid=12486697 |doi-access=free }}</ref> The scientific consensus is that genetics does not explain [[Race and intelligence|average differences in IQ test performance between racial groups.]]<ref>{{Cite journal |last1=Bird |first1=Kevin |last2=Jackson |first2=John P. |last3=Winston |first3=Andrew S. |date=2024 |title=Confronting Scientific Racism in Psychology: Lessons from Evolutionary Biology and Genetics |url=https://psycnet.apa.org/doiLanding?doi=10.1037%2Famp0001228 |journal=American Psychologist |volume=79 |issue=4 |pages=497–508 |doi=10.1037/amp0001228 |pmid=39037836 |quote=Recent articles claim that the folk categories of race are genetically meaningful divisions, and that evolved genetic differences among races and nations are important for explaining immutable differences in cognitive ability, educational attainment, crime, sexual behavior, and wealth; all claims that are opposed by a strong scientific consensus to the contrary.|url-access=subscription }}</ref><ref name=":02">{{cite journal |last1=Nisbett |first1=Richard E. |author-link1=Richard E. Nisbett |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 |url-status=live |journal=American Psychologist |volume=67 |pages=503–504 |doi=10.1037/a0029772 |issn=0003-066X |pmid=22963427 |archive-url=https://web.archive.org/web/20150123114230/http://people.virginia.edu/~ent3c/papers2/Articles%20for%20Online%20CV/Nisbett%20(2012)%20Group.pdf |archive-date=23 January 2015 |access-date=22 July 2013 |number=6}}</ref><ref name=":22">{{Cite journal |last1=Ceci |first1=Stephen |last2=Williams |first2=Wendy M. |date=1 February 2009 |title=Should scientists study race and IQ? YES: The scientific truth must be pursued |journal=Nature |volume=457 |issue=7231 |pages=788–789 |bibcode=2009Natur.457..788C |doi=10.1038/457788a |pmid=19212385 |s2cid=205044224 |quote=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. |doi-access=free}}</ref>