Editing Flynn effect (section)

==Rise in IQ==
IQ tests are updated periodically. For example, the [[Wechsler Intelligence Scale for Children]] (WISC), originally developed in 1949, was updated in 1974, 1991, 2003, and again in 2014. The revised versions are [[standardized]] based on the performance of test-takers in standardization samples. A standard score of IQ 100 is defined as the mean performance of the standardization sample. Thus one way to see changes in norms over time is to conduct a study in which the same test-takers take both an old and new version of the same test. Doing so confirms IQ gains over time. Some IQ tests—for example, tests used for military draftees in [[NATO]] countries in Europe—report raw scores, and those also confirm a trend of rising scores over time. The average rate of increase seems to be about three IQ points per decade in the United States, as scaled by the Wechsler tests. The increasing test performance over time appears on every major test, in every age range, at every ability level, and in every modern industrialized country, although not necessarily at the same rate as in the United States. The increase was continuous and roughly linear from the earliest days of testing to the mid-1990s.<ref name="Neisser97">{{cite journal |author=Neisser U |title=Rising Scores on Intelligence Tests |journal=American Scientist |volume=85 |issue=5 |pages=440–47 |year=1997 |url=http://www.americanscientist.org/issues/feature/rising-scores-on-intelligence-tests/99999 |url-status=deviated |archive-url=https://web.archive.org/web/20161104214157/http://www.americanscientist.org/issues/feature/rising-scores-on-intelligence-tests/99999 |archive-date=November 4, 2016  |bibcode=1997AmSci..85..440N }}</ref>{{better source needed|date=November 2017}} Though the effect is most associated with IQ increases, a similar effect has been found with increases in attention and of [[Semantic memory|semantic]] and [[episodic memory]].<ref name="Rönnlund"/>

[[Ulric Neisser]] estimated that using the IQ values of 1997, the average IQ of the United States in 1932, according to the first [[Stanford–Binet Intelligence Scales]] standardization sample, was 80. Neisser states that "Hardly any of them would have scored 'very superior', but nearly one-quarter would have appeared to be 'deficient.'" He also wrote that "Test scores are certainly going up all over the world, but whether intelligence itself has risen remains controversial."<ref name="Neisser97"/> Quantitative psychologist, [[Joseph Lee Rodgers]] argues that the effect occurs outside of families in any case.<ref>[[Joseph Lee Rodgers]] (2014). "http://www.iapsych.com/iqmr/fe/LinkedDocuments/rodgers2014.pdf  Intelligence Are birth order effects on intelligence really Flynn Effects? Reinterpreting Belmont and Marolla 40 years later" (PDF). ''Intelligence'' 42: 128-133. "No within-family data exist that document an increase in intelligence over birth order, suggesting that its source derives from outside the family and will only manifest in data and analyses that account for between-family variance (such as cross-sectional data)." (p. 130)</ref>

Trahan et al. (2014) found that the effect was about 2.93 points per decade,{{clarify|reason=Over what time interval?|date=March 2023}} based on both Stanford–Binet and Wechsler tests; they also found no evidence the effect was diminishing.<ref>{{cite journal|last1=Trahan|first1=LH|last2=Stuebing|first2=KK|last3=Fletcher|first3=JM|last4=Hiscock|first4=M|title=The Flynn effect: a meta-analysis.|journal=Psychological Bulletin|date=September 2014|volume=140|issue=5|pages=1332–60|doi=10.1037/a0037173|pmid=24979188|pmc=4152423}}</ref> In contrast, Pietschnig and Voracek (2015) reported, in their meta-analysis of studies involving nearly 4 million participants, that the Flynn effect had decreased in recent decades. They also reported that the magnitude of the effect was different for different types of intelligence ("0.41, 0.30, 0.28, and 0.21 IQ points annually for fluid, spatial, full-scale, and crystallized IQ test performance, respectively"), and that the effect was stronger for adults than for children.<ref name="Pietschnig">{{Cite journal |last1=Jakob Pietschnig |last2=Martin Voracek |s2cid=12604392 |date=May 1, 2015 |title=One Century of Global IQ Gains: A Formal Meta-Analysis of the Flynn Effect (1909–2013) |journal=Perspectives on Psychological Science |language=en |volume=10 |issue=3 |pages=282–306 |doi=10.1177/1745691615577701 |pmid=25987509 |issn=1745-6916}}</ref>

Raven (2000) found that, as Flynn suggested, data interpreted as showing a decrease in many abilities with increasing age must be re-interpreted as showing that there has been a dramatic increase of these abilities with the date of birth. On many tests this occurs at all levels of ability.<ref name=R2000>{{cite journal | author = Raven John | year = 2000 | title = The Raven's Progressive Matrices: Change and Stability over Culture and Time | url = http://eyeonsociety.co.uk/resources/RPMChangeAndStability.pdf | journal = Cognitive Psychology | volume = 41 | issue = 1 | pages = 1–48 | doi = 10.1006/cogp.1999.0735 | pmid = 10945921 | s2cid = 26363133 | access-date = July 9, 2011 | archive-date = April 28, 2019 | archive-url = https://web.archive.org/web/20190428221444/http://eyeonsociety.co.uk/resources/RPMChangeAndStability.pdf | url-status = live }}</ref>

Some studies have found the gains of the Flynn effect to be particularly concentrated at the lower end of the distribution. Teasdale and Owen (1989), for example, found the effect primarily reduced the number of low-end scores, resulting in an increased number of moderately high scores, with no increase in very high scores.<ref name=TO1987>{{Cite journal| doi = 10.1016/0160-2896(89)90021-4 | last1 = Teasdale | first1 = T. | title = Continuing secular increases in intelligence and a stable prevalence of high intelligence levels | journal = Intelligence | volume = 13 | issue = 3 | pages = 255–62 | year = 1989 }}</ref> In another study, two large samples of Spanish children were assessed with a 30-year gap. Comparison of the IQ distributions indicated that the mean IQ scores on the test had increased by 9.7 points (the Flynn effect), the gains were concentrated in the lower half of the distribution and negligible in the top half, and the gains gradually decreased as the IQ of the individuals increased.<ref name="Colom2005">{{cite journal | url=http://synapse.princeton.edu/~brained/chapter15/colom_andres-pueyo05_intelligence_Spanish-schoolchildren-nutrition-hypothesis.pdf | title=The generational intelligence gains are caused by decreasing variance in the lower half of the distribution: Supporting evidence for the nutrition hypothesis | author1=Colom, R. | author2=Lluis-Font, J.M. | author3=Andrés-Pueyo, A. | name-list-style=amp | journal=Intelligence | year=2005 | volume=33 | issue=1 | pages=83–91 | doi=10.1016/j.intell.2004.07.010 | access-date=October 4, 2012 | archive-date=August 13, 2012 | archive-url=https://web.archive.org/web/20120813042004/http://synapse.princeton.edu/~brained/chapter15/colom_andres-pueyo05_intelligence_Spanish-schoolchildren-nutrition-hypothesis.pdf | url-status=live }}</ref> Some studies have found a reverse Flynn effect with declining scores for those with high IQ.<ref name="Pietschnig" />

In 1987, Flynn took the position that the very large increase indicates that IQ tests do not measure intelligence but only a minor sort of "abstract problem-solving ability" with little practical significance. He argued that if IQ gains did reflect intelligence increases, there would have been consequent changes of our society that have not been observed (a presumed non-occurrence of a "cultural renaissance").<ref name="Neisser97"/> By 2012 Flynn no longer endorsed this view of intelligence, having elaborated and refined his view of what rising IQ scores meant.<ref>{{Cite news|url=https://www.theguardian.com/technology/2012/sep/23/james-flynn-iq-scores-environment|title=James Flynn: IQ may go up as well as down|last=Tucker|first=Ian|date=2012-09-22|work=The Guardian|access-date=2019-01-21|language=en-GB|issn=0261-3077|archive-date=January 21, 2019|archive-url=https://web.archive.org/web/20190121232649/https://www.theguardian.com/technology/2012/sep/23/james-flynn-iq-scores-environment|url-status=live}}</ref>

===Precursors to Flynn's publications===
Earlier investigators had discovered rises in raw IQ test scores in some study populations, but had not published general investigations of that issue in particular. Historian Daniel C. Calhoun cited earlier psychology literature on IQ score trends in his book ''The Intelligence of a People'' (1973).<ref>{{cite book |last=Calhoun |first=Daniel |title=The Intelligence of a People |date=1973 |publisher=Princeton University Press |isbn=978-0-691-04619-8 |url=https://archive.org/details/intelligenceofpe0000calh |url-access=registration}}</ref> [[Robert L. Thorndike]] – not to be confused with his famous father ''[[Edward Thorndike|Edward]]'' – drew attention to rises in Stanford-Binet scores in a 1975 review of the history of intelligence testing.<ref>{{Cite journal |last=Thorndike |first=Robert L. |author-link=Robert L. Thorndike|title=Mr. Binet's Test 70 Years Later |journal=Educational Researcher |volume=4 |issue=5 |year=1975 |pages=3–7 |issn=0013-189X |doi=10.3102/0013189X004005003 |jstor=1174855 |s2cid=145355731 }}</ref> In 1982, [[Richard Lynn]] recorded an increase in average IQ among the population of Japan.<ref>{{Cite journal |last=Lynn |first=Richard |author-link=Richard Lynn|date=May 1982 |title=IQ in Japan and the United States shows a growing disparity |url=https://www.nature.com/articles/297222a0 |journal=Nature |language=en |volume=297 |issue=5863 |pages=222–223 |doi=10.1038/297222a0 |bibcode=1982Natur.297..222L |s2cid=4331657 |issn=1476-4687}}</ref>

===Intelligence===
{{See also|g factor (psychometrics)|Intelligence (trait)}}
There is debate about whether the rise in IQ scores also corresponds to a rise in general intelligence, or only a rise in special skills related to taking IQ tests. Because children attend school longer now and have become much more familiar with the testing of school-related material, one might expect the greatest gains to occur on such school content-related tests as [[vocabulary]], [[arithmetic]] or general information. Just the opposite is the case: abilities such as these have experienced relatively small gains and even occasional decreases over the years. Meta-analytic findings indicate that Flynn effects occur for tests assessing both fluid and crystallized abilities. For example, Dutch conscripts gained 21 points during only 30 years, or 7 points per decade, between 1952 and 1982.<ref name="Neisser97"/> This rise in IQ test scores is not wholly explained by an increase in general intelligence. Studies have shown that while test scores have improved over time, the improvement is not fully correlated with latent factors related to intelligence.<ref>{{cite journal | vauthors = Must O, Must A, Raudik V | year = 2003 | title = The secular rise in IQs: In Estonia, the Flynn effect is not a Jensen effect | journal = [[Intelligence (journal)|Intelligence]] | volume = 31 | issue = 5 | pages = 461–71 | doi = 10.1016/S0160-2896(03)00013-8 | url = http://www.iapsych.com/iqmr/fe/LinkedDocuments/Must2003.pdf | access-date = September 13, 2011 | archive-date = October 11, 2017 | archive-url = https://web.archive.org/web/20171011193700/http://www.iapsych.com/iqmr/fe/LinkedDocuments/Must2003.pdf | url-status = live }}</ref> Other researchers argue that the IQ gains described by the Flynn effect are due in part to increasing intelligence, and in part to increases in test-specific skills.<ref>{{cite journal |author1=Wicherts, J.M. |author2=Dolan, C.V. |author3=Hessen, D.J. |author4=Oosterveld, P. |author5=Baal, G.C.M. van |author6=Boomsma, D.I. |author7=Span, M.M. |name-list-style=amp |year=2004 |title=Are intelligence tests measurement invariant over time? Investigating the nature of the Flynn effect |journal=[[Intelligence (journal)|Intelligence]] |volume=32 |issue=5 |pages=509537 |url=http://users.fmg.uva.nl/jwicherts/wicherts2004.pdf |doi=10.1016/j.intell.2004.07.002 |quote=The overall conclusion of the present paper is that factorial invariance with respect to cohorts is not tenable . . . . The fact that the gains cannot be explained solely by increases at the level of the latent variables (common factors), which IQ tests purport to measure, should not sit well with explanations that appeal solely to changes at the level of the latent variables. |url-status=dead |archive-url=https://web.archive.org/web/20050529034027/http://users.fmg.uva.nl/jwicherts/wicherts2004.pdf |archive-date=May 29, 2005  |citeseerx=10.1.1.207.4350 }}</ref><ref name=Nijenhuis04>{{cite journal | vauthors= Te Nijenhuis J, De Jong MJ, Evers A, Van Der Flier H | title= Are cognitive differences between immigrant and majority groups diminishing? | journal= [[European Journal of Personality]] | year= 2004 | volume= 18 | issue= 5 | pages= 405–34 | doi= 10.1002/per.511 | s2cid= 4806581 | url= https://research.vu.nl/ws/files/1957002/Nijenhuis%20European%20Journal%20of%20Personality%2018%202004%20u.pdf | access-date= November 10, 2019 | archive-date= February 21, 2021 | archive-url= https://web.archive.org/web/20210221012426/https://research.vu.nl/ws/files/1957002/Nijenhuis%20European%20Journal%20of%20Personality%2018%202004%20u.pdf | url-status= live }}</ref><ref>{{cite journal |title=Secular Gains in Fluid Intelligence: Evidence from the Culture-Fair Intelligence Test |vauthors=Colom R, Garcia-Lopez O| journal= [[Journal of Biosocial Science]] | year= 2003 | volume= 35 | pages= 33–39 | doi= 10.1017/S0021932003000336 | pmid= 12537154 | issue= 1|s2cid=24493926}}</ref> One study suggested that the IQ gains reflected changes in modes of thinking that better reflected cognitive skills assessed by IQ tests rather than raw intelligence itself.<ref>{{cite journal |last1=Flynn |first1=James Robert |last2=Te Nijenhuis |author2-link= Jan te Nijenhuis |first2=Jan |last3=Metzen |first3=Daniel |date=May–June 2014 |title=The g beyond Spearman's g: Flynn's paradoxes resolved using four exploratory meta-analyses |url=https://www.sciencedirect.com/science/article/abs/pii/S0160289614000105 |journal=[[Intelligence (journal)|Intelligence]] |volume=44 |pages=1–10 |doi=10.1016/j.intell.2014.01.009 |access-date=2 July 2023}}</ref>