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Surprising evidence on the Flynn Effect
1. Non-verbal IQ has risen more rapidly than has verbal IQ.
2. Performance gains are smallest on the most culturally specific tests, and largest on the most abstract tests.
3. Performance gains, as they occur over time, are roughly constant for all age groups.
4. Problem-solving abilities have seen the biggest performance gains.
5. Gains on the "Ravens" test started occurring before the TV era, much less the computer game era.
#3 is perhaps the biggest surprise to me, as it contradicts most of the obvious explanations for the Flynn effect.
Those results are summed up in the very interesting "The Flynn effect and its relevance to Neuropsychology," by Merrill Hiscock, Journal of Clinical and Experimental Neuropsychology, 2007. Here is Andrew Gelman's post on that paper.
Hiscock puts it well: "..the Flynn effect constitutes a compelling example of large between-group IQ differences [across generations] that are completely environmental."
Posted by Tyler Cowen on August 15, 2007 at 07:32 AM in Science | Permalink
Comments
Recent papers (Teasdale and Owen, Sundet Barlaugb and Torjussen )have suggested the Flynn effect stopped around 1990 in Northern Europe, though this could be related to immigration by groups that test lower on IQ tests.
Posted by: eric at Aug 15, 2007 9:27:22 AM
5# weakens Steven Johnson's hypothesis in Everything Bad is Good for You, though I can't remember if he said more complicated plots on TV and within video games was either a cause of or was the outcome of rising IQ scores. I seem to remember the former, given the book's title.
Posted by: Rue Des Quatre Vents at Aug 15, 2007 10:00:17 AM
Maybe it's just me, but I've never understood "verbal IQ" as a measure of intelligence. So I haven't been
exposed to that particular word before, that means I'm less intelligent? Less *knowledgeable*, sure,
but why less intelligent?
Posted by: Person at Aug 15, 2007 10:44:16 AM
Regarding verbal IQ, I would imagine it aims to measure, not whether one has been exposed to a certain word, but whether one has retained its meaning.
Posted by: Marc at Aug 15, 2007 11:05:06 AM
1. Non-verbal IQ has risen more rapidly than has verbal IQ.
This isn't surprising at all. Are novels of the 21st century appreciably better than those of the 19th century? It's arguable.
But the leaps in technology—which is done in the currency of math and science—are undeniable.
Or, more succinctly, compare the progress in movie scripts versus those in special effects.
Posted by: nibble at Aug 15, 2007 11:08:03 AM
@eric :
Raven test measures pattern matching ability. This could be attributed to other leisure activities than TV or Videogames ( Board games, card games, fantasy sport games - that's the example on Steven Johnson's book from his childhood - )
The study mentions as the more probable cause a combination of factors ( from nutrition and increased education, lifestyle and work changes , to leisure activities and technology available.)
Posted by: ale at Aug 15, 2007 11:33:17 AM
The Flynn Effect does not appear to have reduced differences (in SD units or, hardly, in points) between mean IQ's of different ethnic groups. So it does not suggest that the genetic contribution to IQ has changed. As many scholars have noted, when you minimize variations in environment which contribute to differences in IQ (or anything else), then any differences caused by genetic factors become more, not less visible. What this means for politics I leave to the reader.
[1] Except perhaps on the basis of selection over multiple generations. Future biotech innovations may alter this.
Posted by: Mark Seecof at Aug 15, 2007 11:48:08 AM
Regarding verbal IQ, I would imagine it aims to measure, not whether one has been exposed to a certain word, but whether one has retained its meaning.
And I think you'd have to be exposed to its meaning in the first place to be able to retain it.
Posted by: Person at Aug 15, 2007 12:17:36 PM
Verbal IQ should not be interpreted literary. It’s also a measure of broad analytical/judgment/creative, that is *measures* using verbal tests (antonyms). This requires you to understand and abstractly think about what words mean.
Of course it also measures language comprehension and word knowledge. What economists often call “intuition” is probably largely verbal IQ.
Think lawyer or public intellectual, rather than linguist or poet (the two other also have high verbal IQ, but the two former show why it matters).
Posted by: Tino at Aug 15, 2007 1:38:12 PM
From Review (3/2007, R. Lynn)
"Flynn attempts to refute the nutrition theory of the Flynn Effect by asserting that there is no evidence that nutrition has improved in the second half of the twentieth century. He asserts that there have been no increases in height (improvements in nutrition are indexed by increases in height) in the United States in children born after about 1952, although intelligence has continued to increase. Contrary to this contention (1) the data compiled by Komlos and Lauderdale (in press) show that height in the United States increased in those born from 1955 to 1975 (white men from 177.8 to 179.5; white women from 164.1 to 164.9); (2) height stabilised after 1975 and Flynn's own data show that intelligence gains decelerated after 1985 and turned negative in children from 1989 to 1995. In Europe also heights increased from 1960 to 1990 (Larnkjaer, Schroder et al., 2006); from around 1990 heights and intelligence have both stabilized in Denmark and Norway. The case for improvements in height running parallel with increases in intelligence, as predicted by the nutrition theory, is much stronger that Flynn allows.
Furthermore, the nutrition theory of the Flynn Effect explains why fluid intelligence has increased so much more than crystallized intelligence. Several studies have shown that sub-optimal nutrition impairs fluid intelligence more than crystallized intelligence. Hence as nutrition has improved over time, fluid intelligence has increased more. It has even been shown that the Wechsler subtests that are most impaired by sub-optimal nutrition and improve most with nutritional supplements are those for which the Flynn Effects have been the greatest (e.g. arithmetic, similarities and block design) (Botez, Botez, & Maag, 1984)."
Posted by: Tino at Aug 15, 2007 1:52:48 PM
Tino, I understand that, but in order to get a verbal IQ test question right, you generally have to BOTH
be able to reason properly, AND have the requisite language *knowledge*. So missing it means you either
couldn't reason, or didn't know of that word. Since there's such a big reason to miss it for non-intelligence
reasons, I don't see why it's considered an intelligence test.
Posted by: Person at Aug 15, 2007 1:54:57 PM
Thanks. The biggest mystery involving the Flynn Effect is why it has had so little impact on changing the relative standing of groups. For example, in 2006, Lynn reported on IQ studies of Japanese in Japan showing average scores have been a little over 100 (on a scale where the British are 100) for 23 studies of Japanese born from 1940 to 1990. In contrast, 17 studies of Hispanics in the U.S. born from 1910 to 1990 showed an average around 90. And 17 studies of Australian Aborigines born between 1900 and 1990s showed averages in the 60s.
There was variation around these means but the trendlines were close to flat and there was no overlap on any of the 57 studies (i.e., the Japanese always averaged higher than the Hispanic-Americans who always averaged higher than the Aborigines).
Lynn adjusted all these scores for the Flynn Effect, which smoothed out the results considerably.
You might expect diminishing marginal returns to whatever is driving the Flynn Effect to come into play, but there isn't much evidence for that through 1990.
http://www.vdare.com/sailer/060423_lynn.htm
Posted by: Steve Sailer at Aug 15, 2007 2:31:44 PM
The test for verbal IQ is basically an advanced vocabulary test.
A person's verbal IQ is largely determined by the number of words and the concepts underlying those words he has learned. But learning words and concepts is a "linear additive set" which means that learning one word/concept gives little advantage in learning the next word/concept. Thus, the learning of vocabulary is not amenable to acceleration through improved teaching techniques. Learning vocabulary is a slow slog that is limited by the person's verbal IQ. People with low verbal IQs learn more slowly than people with high verbal IQs and there is litle we can do (at least currently) to help them catch up.
See Wes Becker's 1977 article from the Harvard Educational Review Teaching Reading and Language to the Disadvantaged—What We Have Learned from Research:
In contrast to the general-case learning involved in decoding, arithmetic, grammar, and spelling-by-sounds, the learning of vocabulary and concepts usually involves a “linear-additive set” (Becker & Engelmann, 1976, p. 58). In a linear additive set, the learning of one element gives little advantage in learning a new element. To be sure, there are families of words that have common root meanings and common meanings of affixes, which permit some limited general cases to be generated. But, by and large, the learning of proper names, new concepts, and the learning of synonyms for concepts already known by another name, involve linear additive sets in which each new element must be taught. Knowledge of the English language, which is absolutely essential to oral and written comprehension, serves largely to define intelligent behavior (Miner, 1957). Teaching this language involves a task of the first magnitude.Schools have never had programs in reading that systematically build vocabulary concept knowledge. Except for technical vocabularies, this task has been largely left to parents. Furthermore, since the achievement tests are built by procedures that measure age changes, and not simply the effects of school instruction, children from homes with weak support for language development fall progressively behind on current reading tests. This finding is commonly reported.
Basically verbal, IQ is the limiting factor for how much a person is capable of learning since it determines the speed at which new words/concepts are learned which determines the person's ability to comprehend the increasingly sophisticated language in higher learning.
Posted by: KDeRosa at Aug 15, 2007 3:07:23 PM
Awhile ago, Tyler proclaimed that people he knew in a poor, backward village in Mexico seemed "smart" to him because they are lively gossips. You can define the world "smart" as anything you like, but from an economic perspective, the important thing about IQ is that it can be used to predict a variety of real world outcomes with more accuracy than is common in the fuzzy world of the social sciences. Consider Tyler's friends, who he says have low IQs, but seem smart to him:
- Do they achieve a lot academically? No.
- Do they achieve a lot economically? No.
- Do they invent a lot of useful new technology or techniques? No.
- Do they avoid a lot of drunken accidents? No.
So, what has more real world usefulness to the social scientist? IQ or TIQ (Tyler-Impressing Quotient)?
Which tool, however, will continue to be underexploited in the field of economics for careerist reasons? You guessed it: IQ.
Posted by: Steve Sailer at Aug 15, 2007 3:29:53 PM
Given what we know about the Flynn it seem safe to assume that our ancestors group IQ was lower than that Americans and Europeans today and probably below Tyler's villagers. However they achieved a lot economically and invented a lot of useful new technologies, although they didn't do much academically and got into a lot of drunken accidents.
Posted by: joan at Aug 15, 2007 5:35:28 PM
I think it suggests that this has nothing to do with intelligence but only with exposure and conformance to a set of common culture on what is believed to be intelligence.
Posted by: Lord at Aug 15, 2007 5:47:02 PM
The Flynn effect implies that mean IQ 100 years ago was much lower than it is today; however, there are plenty of examples of genius form those times that we can draw on. So, assuming *mean* IQ has been rising, does that mean the entire distribution has been shifted higher, or merely that its shape has changed? We know that *mean* IQ is higher, but does that necessarily imply that we have more geniuses than before? In other words, how normal is the distribution - what has been happening in the tails? The really useful information regarding the Flynn effect would be more detailed information on how the IQ distribution within ethnic groups has changed over time. We know that the *mean* has been changing - what about the *variance*, the *skew*, and the *kurtosis*? Assuming the Flynn effect is due to better nutrition, this info could be of extreme usefulness in predicting how the average IQ of currently malnourished countries will change if nutrition improves.
P.S. for a graphical illustration of mean, variance, skew, and kurtosis, check here: http://en.wikipedia.org/wiki/Skewness http://en.wikipedia.org/wiki/Kurtosis#Terminology_and_examples
Posted by: pwyll at Aug 15, 2007 7:34:22 PM
I think it suggests that this has nothing to do with intelligence but only with exposure and conformance to a set of common culture on what is believed to be intelligence.
Unfortunately, the "common culture" is Western culture, i.e., the industrialized, developed world, which is what everyone (outside of radical Islam) is pretty much aspiring to succeed at. If the undeveloped world (or the underclass in the developed world) were aspiring to a hunter-gatherer culture or female farming (where lives were probably better than European peasants of 300 years ago) or medieval theocracy then we could just throw away these inconvenient IQ results as curiosities. But if success in modern industrialized cultures is important, then we ought to be paying more attention to IQ scores, not less.
Posted by: ziel at Aug 15, 2007 8:19:00 PM
Right, as a topic for economists looking for something important and powerful to research, IQ is the twenty-dollar bill lying on the sidewalk while the entire economics profession walks by.
Some economist should write about this as a classic example of market failure.
Posted by: Steve Sailer at Aug 15, 2007 8:26:39 PM
Since you've come back to this topic a few times, could you perhaps do a formal introduction to your new colleague Garrett Jones? I know he has figured heavily in the comments to earlier posts, but his work is interesting and maybe not everyone realizes he will be joining you at Mason in the fall?
Posted by: bh at Aug 15, 2007 10:37:00 PM
"Which tool, however, will continue to be underexploited in the field of economics for careerist reasons? You guessed it: IQ."
Sailer,
Can't you comment without speculating on people's motives? All this post does is summarize some facts about the Flynn Effect and you can't resist turning the comment box into a speculations about others motives.
Posted by: Stephen B at Aug 15, 2007 10:43:07 PM
And yet there is an enormously deep compliment is the frequency with which he (Sailer or the person known as) reads and comments on the blog that says more about the respect we all hold for the authors of the blog than almost anything else I have seen or read anywhere. So, while the inaptness of the comments is not appealing or compelling, we might as well respect what we can and hope the social skills improve with practice.
Posted by: iam at Aug 15, 2007 11:26:31 PM
Stephen B: of course he could. But why should he?
The motivations here are, after all, so very interesting.
Posted by: Steve Burton at Aug 15, 2007 11:44:36 PM
Because, as all economists know, the economic concept of "self-interest" applies to all human beings ... except, oddly enough, economists.
Posted by: Steve Sailer at Aug 16, 2007 1:56:35 AM
"I understand that, but in order to get a verbal IQ test question right, you generally have to BOTH
be able to reason properly, AND have the requisite language *knowledge*. "
Mwah, doesn't the same hold for quantitative tests? If you haven't encountered the square root sign or Pygatoras' theorem before, you won't solve many geometry questions.
Posted by: JSK at Aug 16, 2007 8:54:42 PM
