Editing Flynn effect (section)

===Generally more stimulating environment===
Still another theory is that the general environment today is much more complex and stimulating. One of the most striking 20th-century changes in the human intellectual environment has come from the increase of exposure to many types of [[visual media]]. From pictures on the wall to movies to television to video games to computers, each successive generation has been exposed to richer optical displays than the one before and may have become more adept at visual analysis. This would explain why visual tests like the Raven's have shown the greatest increases. An increase only of particular forms of intelligence would explain why the Flynn effect has not caused a "cultural renaissance too great to be overlooked."<ref name="Neisser97"/>

In 2001, [[William Dickens]] and James Flynn presented a model for resolving several contradictory findings regarding IQ. They argue that the measure "[[heritability]]" includes both a direct effect of the [[genotype]] on IQ and also indirect effects such that the genotype changes the [[Environment (biophysical)|environment]], thereby affecting IQ. That is, those with a greater IQ tend to seek stimulating environments that further increase IQ. These reciprocal effects result in [[gene environment correlation]]. The direct effect could initially have been very small, but [[feedback]] can create large differences in IQ. In their model, an environmental stimulus can have a very great effect on IQ, even for adults, but this effect also decays over time unless the stimulus continues (the model could be adapted to include possible factors, like nutrition during early childhood, that may cause permanent effects). The Flynn effect can be explained by a generally more stimulating environment for all people. The authors suggest that any program designed to increase IQ may produce long-term IQ gains if that program teaches children how to replicate the types of cognitively demanding experiences that produce IQ gains outside the program. To maximize lifetime IQ, the programs should also motivate them to continue searching for cognitively demanding experiences after they have left the program.<ref name=Dickens01>{{cite journal |doi=10.1037/0033-295X.108.2.346 |vauthors=Dickens WT, Flynn JR |title=Heritability estimates versus large environmental effects: The IQ paradox resolved |journal=Psychological Review |volume=108 |issue=2 |pages=346–369 |year=2001 |pmid=11381833 |url=https://www.psychologytoday.com/files/u81/Dickens_and_Flynn__2001_.pdf|citeseerx=10.1.1.139.2436 }}</ref><ref>{{cite journal|vauthors=Dickens WT, Flynn JR |title=The IQ Paradox: Still Resolved |journal=Psychological Review |volume=109 |issue=4 |year=2002 |url=http://www.brookings.edu/views/papers/dickens/20020205.pdf |doi=10.1037/0033-295x.109.4.764 |pages=764–71 |url-status=dead |archive-url=https://web.archive.org/web/20070319031706/http://www.brookings.edu/views/papers/dickens/20020205.pdf |archive-date=March 19, 2007  }}</ref>

Flynn, in his 2007 book ''[[What Is Intelligence?]]'', further expanded on this theory. Environmental changes resulting from modernization—such as more intellectually demanding work, greater use of technology, and smaller families—have meant that a much larger proportion of people are more accustomed to manipulating abstract concepts such as hypotheses and categories than a century ago. Substantial portions of IQ tests deal with these abilities. Flynn gives, as an example, the question 'What do a dog and a rabbit have in common?' A modern respondent might say they are both mammals (an abstract, or ''a priori'' answer, which depends only on the meanings of the words ''dog'' and ''rabbit''), whereas someone a century ago might have said that humans catch rabbits with dogs (a concrete, or ''a posteriori'' answer, which depended on what happened to be the case at that time).<ref>{{cite book |last=Flynn |first=James R. |author-link=James Flynn (academic) |title=[[What Is Intelligence?|What Is Intelligence? Beyond the Flynn Effect]] |date=August 2012 |publisher=Cambridge University Press |isbn=9780511605253 |pages=24–29}}</ref><ref>{{cite magazine |last1=Gladwell |first1=Malcolm |title=None of the Above |url=https://www.newyorker.com/magazine/2007/12/17/none-of-the-above |magazine=The New Yorker |access-date=July 6, 2024 |date=December 10, 2007 |url-access=limited}}</ref>{{Better source needed|date=July 2024}}