How real is the Flynn effect?

 

Changes in mean IQ between 1909 and 2013 (Pietschnig and Voracek 2015, p. 285)

 

 

Because of the Flynn effect, average IQ has risen by 35 points over the past century. That’s more than the difference between the threshold of mental retardation and the current average. Does that seem plausible?

 

In a 1984 paper, James Flynn showed that the mean IQ of White Americans rose by 13.8 points between 1932 and 1978 (Flynn 1984). When that increase, now called the Flynn effect, was charted between 1920 and 2013, the gain in IQ was found to be no less than 35 points (Pietschnig and Voracek 2015).

 

The IQ gain did not happen at a uniform rate. It can be broken down into five stages:

 

·         a small increase between 1909 and 1919 (0.80 points/decade)

·         a surge during the 1920s and early 1930s (7.2 points/decade)

·         a slower pace of growth between 1935 and 1947 (2.1 points/decade)

·         a faster one between 1948 and 1976 (3.0 points/decade)

·         a slower pace thereafter (2.3 points/decade)

 

The Flynn effect began in the core of the Western world and is now ending there. In fact, it has ended altogether in Norway and Sweden and has begun to reverse itself in Denmark and Finland (Pietschnig and Voracek 2015, pp. 283, 288-289).

 

Was it a real increase?

 

Average IQ has thus risen by 35 points over the past century. That’s more than the difference between the threshold of mental retardation and the current average. Does that seem plausible?

 

My mother went to high school during the 1930s, and I went during the 1970s. So my generation should be 13.8 points smarter than hers. That’s a big difference, and it should have been obvious to someone like myself who knew people from both generations.

 

It wasn’t obvious. My mother had a small library of books that she often consulted, mostly religious literature and works like Welcome Wilderness and Little Dorrit. Not all of her generation were obsessive readers, but many were. And the books they read weren’t light reading. Fiction typically had complex plots with subplots running alongside each other, and religious books were a maze of Biblical references that would seem obscure unless you knew the Bible, usually the King James Version. If you could handle that, you could handle string theory.

 

The Flynn effect also implies that post-millennials are 10 points smarter than my generation. Again, that’s not my impression. Books and movies now have simpler plots and use a smaller vocabulary—a key component of verbal intelligence. According to the General Social Survey, vocabulary test scores fell by 7.2% between the mid-1970s and the 2010s among non-Hispanic White Americans. The decline affected all levels of educational attainment, so it wasn’t just a matter of dumber people now going to college (Frost 2019; Twenge et al. 2019). The same period also saw an increase in reaction time: since the 1970s, successive birth cohorts have required more time, on average, to process the same information (Madison 2014; Madison et al. 2016). 

 

Finally, there is the genetic evidence, specifically alleles associated with high educational attainment. In Iceland, those alleles have become steadily fewer in cohorts born since 1910 (Kong et al. 2017). The same trend has been observed between the 1931 and 1953 birth cohorts of European Americans (Beauchamp 2016). According to the Icelandic study, the downward trend is happening partly because more intelligent Icelanders are staying in school longer and postponing reproduction. But it is also happening among those who do not pursue higher education. Modern culture seems to be telling people that children are costly and bothersome, and that message is most convincing to people who like to plan ahead.

 

Some writers have argued that the genetic decline in intellectual potential has been more than offset by improvements to our learning environment, particularly better and longer education. This improved environment is helping us do more with our intellectual potential. But is there real-world evidence that we are, on average, becoming smarter? Robert Howard (1999, 2001, 2005) cites four lines of evidence:

 

·        The prevalence of mild mental retardation has fallen in the US population and elsewhere.

·        Chess players are reaching top performance at earlier ages.

·        More journal articles and patents are coming out each year.

·        According to high school teachers who have taught for over 20 years, “most reported perceiving that average general intelligence, ability to do school work, and literacy skills of school children had not risen since 1979 but most believed that children's practical ability had increased” (Howard 2001).

 

The above evidence is debatable, as Howard himself acknowledges. Fewer children are being diagnosed as mental retarded because that term has become stigmatized. Prenatal screening has also had an impact. As for chess, it’s a niche activity that tells us little about the general population. More journal articles are indeed being published each year, but the reason has more to do with pressure to “publish or perish.” Finally, teachers are not objective observers: they are part of a system that rewards certain views and penalizes others. And if they reject that system, they probably won’t stick around for more than twenty years.

 

A last word

 

I suspect we’re getting better at some cognitive tasks, particularly the ones we learn at school—if only because we’re spending more of our lifetime in the classroom. One of those tasks is sitting down at a desk and taking a test. We’re better not only at that specific task but also at the broader one of thinking in terms of questions and answers. Previously, we just learned the rules and imitated those who knew better than us.

 

Test-taking certainly made an impression on my mental development. Long after my undergrad studies I would have nightmares of sitting alone in an immense exam hall and not knowing the answer to an insoluble question.

 

References

 

Beauchamp, J.P. (2016). Genetic evidence for natural selection in humans in the contemporary United States. Proceedings of the National Academy of Sciences. 113(28): 7774-7779. https://doi.org/10.1073/pnas.1600398113  

 

Flynn, J.R. (1984). The mean IQ of Americans: Massive gains 1932–1978. Psychological Bulletin 95(1):29–51. https://psycnet.apa.org/doi/10.1037/0033-2909.95.1.29   

 

Frost, P. (2019). Why is vocabulary shrinking? Evo and Proud, September 11. https://evoandproud.blogspot.com/2019/09/why-is-vocabulary-shrinking.html

 

Frost, P. (2020). From here it’s all downhill. Evo and Proud, March 16. https://evoandproud.blogspot.com/2020/03/from-here-its-all-downhill.html

 

Howard, R. W. (1999). Preliminary real-world evidence that average human intelligence really is rising. Intelligence 27: 235–250. https://doi.org/10.1016/S0160-2896(99)00018-5  

 

Howard, R. W. (2001). Searching the real world for signs of rising population intelligence. Personality and Individual Differences 30: 1039–1058. https://doi.org/10.1016/S0191-8869(00)00095-7

 

Howard, R. W. (2005). Objective evidence of rising population ability: A detailed examination of longitudinal chess data. Personality and Individual Differences, 38(2), 347–363. https://doi.org/10.1016/j.paid.2004.04.013

 

Kong, A., M.L. Frigge, G. Thorleifsson, H. Stefansson, A.I. Young, F. Zink, G.A. Jonsdottir, A. Okbay, P. Sulem, G. Masson, D.F. Gudbjartsson, A. Helgason, G. Bjornsdottir, U. Thorsteinsdottir, and K. Stefansson. (2017). Selection against variants in the genome associated with educational attainment. Proceedings of the National Academy of Sciences 114(5): E727-E732.  https://doi.org/10.1073/pnas.1612113114

 

Madison, G. (2014). Increasing simple reaction times demonstrate decreasing genetic intelligence in Scotland and Sweden, London Conference on Intelligence. Psychological comments, April 25 #LCI14 Conference proceedings. http://www.unz.com/jthompson/lci14-questions-on-intelligence/    

 

Madison, G., M.A. Woodley of Menie, and J. Sänger. (2016). Secular Slowing of Auditory Simple Reaction Time in Sweden (1959-1985). Frontiers in Human Neuroscience, August 18. https://doi.org/10.3389/fnhum.2016.00407

 

Pietschnig, J., and M. Voracek. (2015). One Century of Global IQ Gains: A Formal Meta-Analysis of the Flynn Effect (1909-2013). Perspectives on Psychological Science 10(3): 282-306. https://doi.org/10.1177/1745691615577701

 

Twenge, J.M., W.K. Campbell, and R.A. Sherman. (2019). Declines in vocabulary among American adults within levels of educational attainment, 1974-2016. Intelligence 76: 101377. https://doi.org/10.1016/j.intell.2019.101377