How real is the Flynn effect? Part II

 

Can you pass a Grade 8 exam that was given to American children in 1912? Why the Flynn effect never really happened.

 

 

My last post elicited a tweet from Elon Bachman:

 

Argument by incredulity (w.r.t. retardation) bedevils discussions of intelligence data. What's striking about most retards is the *congenital* speech & motor impairment, not the level of g. Height also increased 1 SD last century. There used to be a lot of malnourished peasants. @ElonBachman

 

In a population with an average IQ of 100, an IQ below 70 is usually due to abnormal circumstances, either freak accidents during pregnancy or rare mutations that haven’t been eliminated by natural selection. In either case, the adverse effects are wide-ranging and affect many aspects of mind and behavior. If your IQ is below 70, you’re lacking in much more than cognitive ability. You probably suffer from various speech and motor impairments. In short, you look and act “funny.”

 

A century ago, if we use current norming of IQ tests, average IQ was below 70 in the Western world. Yet it was not associated with looking and acting “funny.” How come?  For Elon Bachman, this is because an IQ of 70 was normal back then. It was not an outcome of freak accidents or rare mutations. The mental deficit was therefore confined to cognitive ability alone.

 

I understand that argument. Nonetheless, the increase in IQ between then and now is still 35 points—more than two standard deviations. Such a difference in cognitive ability should be visible in popular culture, particularly the books and newspapers that people read. It should also be visible in the academic requirements of elementary school, which was compulsory by that time in most North American jurisdictions.

 

The following are some questions from a Grade 8 exam that was given in 1912 to children in Bullitt County, Kentucky:

 

Find cost at 12½ cents per sq. yd. of kalsomining the walls of a room 20 ft. long, 16 ft. wide and 9 ft. high, deducting 1 door 8 ft. by 4 ft. 6 in. and 2 windows 5 ft. by 3 ft. 6 in. each.

 

A man sold a watch for $180 and lost 16 2/3%. What was the cost of the watch?

 

How many parts of speech are there? Define each.

 

What is a personal pronoun? Decline I.

 

Define longitude and latitude.

 

Tell what you know of the Gulf Stream.

 

Through what waters would a vessel pass in going from England through the Suez Canal to Manila?

 

Compare arteries and veins as to function. Where is the blood carried to be purified?

 

Define Cerebrum; Cerebellum.

 

Define the following forms of government: Democracy, Limited Monarchy, Absolute Monarchy, Republic. Give examples of each.

 

Name five county officers and the principal duties of each.

 

What is a copyright? Patent right?

 

Describe the Battle of Quebec.

 

Name the last battle of the Civil War; War of 1812; French and Indian War and the commanders in each battle.

 

Those are only a few of the questions. The full exam is here.

 

I understand why some want to believe that Western societies were much less intelligent a century ago. If we cannot use IQ to compare different populations over time, perhaps we cannot use it to compare different populations over space, i.e., in different parts of the world. And then what?

 

I’ve heard that sort of argument before. “If we accept genetic determinism for this, we may have to accept it for that. And then what?” If that’s your frame of mind, I have nothing more to say.

 

The increase in IQ and the increase in height during the 20th century

 

But what about the increase in height? That was real. If insufficient nutrition held back height during the 20th century, it should have also held back cognitive ability. The assumption here is that IQ and height are equally constrained by nutrition during development. Has that assumption been tested?

 

It has. The Dutch suffered a terrible famine during the winter of 1944-1945, as did much of continental Europe. Yet that famine had no discernable impact on the mental development of unborn children from that time:

 

A detailed retrospective study was made of 125,000 19-yr-old male Dutch military inductees of whom 20,000 were exposed to the Netherland's winter famine, 1944-1945, through maternal starvation. […] Findings show that (a) starvation during pregnancy had no detectable effects on adult mental performance of surviving male offspring. (b) Mental performance of surviving adult males from the entire population had no association with changing levels of mean birth weight in a hospital sample from the population. And (c) there was a strong association of social class with mental performance. (Stein et al. 1972)

 

It isn’t as if the Flynn effect didn’t occur in the Netherlands, As James Flynn points out:

 

As for nutrition, to my knowledge no one has actually shown that American or British or Western European children have a better diet today than they did in 1950, indeed, the critics of junk food argue that diets are worse. Yet, post-1950 IQ gains have been very large. Military samples tested in 1952, 1962, 1972, and 1982 show that Dutch males made a 20-point gain on a Raven’s-type test (Flynn, 1987, p. 172). Even the latest period shows a huge gain, that is, the Dutch 18-year olds tested in 1982 outscored the Dutch 18-year olds tested in 1972 by fully 8 IQ points. Did the quality of the Dutch diet really escalate that much in 10 years? The gains posted by the 1962 males over the 1952 males are interesting. (Flynn 2008)

 

Those 1962 males were born or still in the womb during the 1944-45 famine. Yet they “do not show up even as a blip in the pattern of Dutch IQ gains” (Flynn 2008). One could argue that the famine was too brief to affect cognitive ability. Perhaps malnutrition needs a longer time span to affect mental development. And again, what about the increase in height? What was driving that increase?

 

We don’t know for sure. We do know that height increased independently of the increase in IQ.

 

Norway was cited above as a nation in which the nutrition hypothesis is viable thanks to greater gains in the lower half of the IQ distribution. Actually, it counts against the posited connection between height gains and IQ gains. Height gains have been larger in the upper half of the height distribution than in the lower half (Sundet et al., 2004). This combination, greater height gains in the upper half of the distribution, greater IQ gains in the lower, poses a serious problem. Are there two kinds of enhanced nutrition, one of which raises height more than it does IQ, the other of which raises IQ more than it does height? (Flynn 2008)

 

There is no common cause behind the increase in IQ and the increase in height. The latter seems to be due to people eating a more varied diet after the Second World War. In particular, fewer and fewer people were subsisting largely on bread. That food item is problematic not only because it lacks many nutrients but also because it has a high content of phytic acid, which binds to calcium and other essential minerals in the food we eat (Harrison and Mellanby 1939; McCance and Widdowson 1942a; McCance and Widdowson 1942b; Sandstead 1992). With the postwar boom, and with efforts to educate people about the benefits of a balanced diet, bread made up a smaller and smaller proportion of total food intake. Bones could now fully develop.

 

Excessive consumption of bread, and the resulting lack of essential minerals, constrained skeletal development during the early 20th century. But it did not constrain cognitive ability.

 

References

 

Flynn, J.R. (2008). Requiem for nutrition as the cause of IQ gains: Raven's gains in Britain 1938-2008. Economics and Human Biology 7(1):18-27. https://doi.org/10.1016/j.ehb.2009.01.009

 

Harrison, D.C., and E. Mellanby. (1939). Phytic acid and the rickets-producing action of cereals. Biochemical Journal 33: 1660-1680. https://doi.org/10.1042%2Fbj0331660

 

McCance, R.A., and E.M. Widdowson. (1942a). Mineral metabolism of healthy adults on white and brown bread dietaries. The Journal of Physiology 101: 44-85. https://doi.org/10.1113%2Fjphysiol.1942.sp003967

 

McCance, R.A., and E.M. Widdowson. (1942b). Mineral metabolism on dephytinized bread. The Journal of Physiology 101: 304-313. https://doi.org/10.1113%2Fjphysiol.1942.sp003984

 

Sandstead, H.H. (1992). Fiber, phytates, and mineral nutrition. Nutrition Reviews 50: 30-31. https://doi.org/10.1111/j.1753-4887.1992.tb02464.x

 

Sieczkowksi, C. (2013). 1912 Eighth-Grade Exam Stumps 21st-Century Test Takers. Could You Pass This Eighth-Grade Exam from 1912? Huffpost, August 12. https://www.huffpost.com/entry/1912-eighth-grade-exam_n_3744163

 

Stein, Z., M. Susser, G. Saenger, and F. Marolla. (1972). Nutrition and mental performance. Science 178(4062): 708–713. https://doi.org/10.1126/science.178.4062.708

 

Sundet, J.M., D.G. Barlaug, and T.M. Torjussen. (2004). The end of the Flynn effect? A study of secular trends in mean intelligence test scores of Norwegian conscripts during half a century. Intelligence 32: 349– 362. https://doi.org/10.1016/j.intell.2004.06.004

 

 

 

 

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