January 21, 2017

The Flynn Effect, Race, and IQ

For the last hundred years or so, each generation has scored higher than the previous one on IQ tests. The average IQ of populations has been rising. This is called “The Flynn Effect” and is named after James Flynn, a political philosopher and IQ researcher who helped discover the international nature of this trend.

Some people believe that the Flynn effect refutes the idea that racial IQ differences are partially caused by genetics. People making this argument often appeal to the fact that the IQ of African Americans today is equal to or higher than the IQ of White people in the past. This is true, but implies nothing about why Black people score worse than White people on IQ tests. Two groups differing genetically by X magnitude in some trait does not preclude the possibility of variation in the environment causing differences in the relevant trait of an even greater magnitude.

Consider a hypothetical garden in which two crops of corn, crop A and crop B, were planted in poor soil. Let’s suppose that corn stocks from crop A were, on average, 5 inches taller than corn stocks from crop B. Now, imagine that the bad soil of the garden was replaced with good soil and, as a result, the height of both crops increased by an average of 6 inches. Because both crop’s height increased by the same amount, the 5-inch gap between crop A and crop B remains.

What does this “Flynn Effect” in height tell us about the causes of the crop height gap? Nothing. This story is obviously fully consistent with the gap being entirely due to genes, the environment, or some combination of the two, even though crop B stocks of the “good soil generation” are taller than crop A stocks of the “poor quality soil generation”.

The same logic can be applied to individual differences: that the environment can cause large IQ differences between people over generations tells us nothing about why people within a single generation differ in IQ.

The economist Thomas Sowell does not commit the fallacious reasoning just outlined, but he does say this about the fact that Black American’s mean IQ score has risen by more than 15 points in the 20th century:

“Since the black-white difference in IQ is 15 points, this means that an even larger IQ difference has existed between different generations of the same race, making it no longer necessary to attribute IQ differences of this magnitude to genetics. In the half century between 1945 and 1995, black Americans’ raw test scores rose by the equivalent of 16 IQ points.” – Sowell (2001)

Even this seemingly conservative statement is incorrect. This is because the Flynn effect represents an increase in cognitive abilities which are different than the cognitive abilities that the races differ in.

To understand how we know this, we must first note that answering each question on an IQ test requires the mind to employ many cognitive abilities at once. For instance, a common question has people listen to a string of numbers read out loud and then has them repeat the number in the opposite order that they were heard in. To answer this question, a person must employ several abilities in order to save this information in their immediately accessible memory and reorganize the information so that they can repeat it back in reverse. This is an easy example, but even the most basic measures of pattern recognition require our minds to do multiple things in-order to produce an answer.

There are some extremely basic mental abilities, called “general intelligence” or “the G factor” which are involved in all the cognitive tasks included in IQ tests. There are other “item specific” cognitive abilities that are only needed to answer specific questions.

For instance, “general processing speed” may be part of general intelligence and may help people add numbers. However, people who can generally think equally quickly may still differ in how fast they can add.

We can measure the degree to which a given question requires general intelligence, as opposed to item specific cognitive abilities, by measuring how well scores on that question predict a person’s scores on all the other questions on an IQ test.

It has been found that there is a positive correlation between how well a question measures general intelligence and how much the races differ in it. This implies that racial IQ gaps are primarily gaps in general intelligence.

Studies have also shown that there is a negative correlation between how well a question measures general intelligence and how much that question was impacted by the Flynn effect. This suggests that the Flynn effect has consisted in a rise of item specific cognitive abilities.

Thus, the Flynn effect mostly (though perhaps not entirely) represents an increase in cognitive abilities which are different than the cognitive abilities which the races differ in.

Moreover, to the degree that both phenomena involve the same abilities, their causes are different. Researchers have determined that this is the case using the following logic: if the Flynn effect has the same causes as the Black/White IQ gap then the more a cognitive ability has been impacted by the Flynn effect the more it should differ racially.

For instance, suppose that IQ differences between the races and generations were both caused by the same nutritional deficiency. Suppose further that this nutritional deficiency has a very large impact on a person’s ability to recognize patterns but a very small impact on their vocabulary. If this is the case, then we would expect pattern recognition to differ more than vocabulary both between generations and between the races.

More generally, if the two gaps have the same cause, regardless of what that cause is, then the items which differ the most across generations should also differ the most across races.

Empirical studies have investigated this and found a negative correlation between the degree to which a cognitive ability is impacted by the Flynn effect and the degree to which it differs racially. This implies that, to the degree that the two phenomena involve the same abilities, they have different causes.

Even James Flynn, a well-known egalitarian in the race and IQ debate, has made the following statement:

“The magnitude of white/ black IQ differences on Wechsler subtests at any given time is correlated with the g loadings of the subtests; the magnitude of IQ gains over time on subtests is not usually so correlated; the causes of the two phenomena are not the same.” – Flynn 2013

In conclusion, the Flynn effect and racial intelligence differences have nothing to do with each other. Intelligence differences between races and between generations are largely gaps in different abilities, to the degree that they are gaps in the same abilities they are produced by different causes, and the existence of a large gain in intelligence over time has no a priori implications on the causes of racial intelligence differences.

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  • melonhead

    I’ve heard Flynn being praised by other IQ researchers as being an honest man, his lefty-ism notwithstanding.

    The idea of more g-correlated vs less g-correlated questions on IQ tests raises the question, though – why don’t people try to hone in on and make, just /more/ g-correlated questions?

  • Herbert Spencer

    The fact is that just as the average heights of people are increasing worldwide due to better nutrition, so too are average IQ scores increasing worldwide, for similar reasons. What I don’t expect to happen is that the average heights of all the populations on Earth will converge to the same height, just as I don’t expect the average IQ scores of all these populations to converge to the same score. Nevertheless, one might argue that past a certain threshold IQ inequalities between populations won’t matter as much as they do today (if, for example, everybody had an IQ score above 100). Of course, it remains to be seen whether or not the Flynn Effect is “powerful” enough for that to happen, and I suspect that for some populations it simply isn’t (say for Australian Aboriginals or African Pygmies).

  • Mark Martinson

    If anything the Flynn effect is evidence for hereditarianism. The gap is staying the same. If it were a real increase in intelligence, you’d expect the blacks to catch up over ttime but that’s not happening.

    • melonhead

      There’s a small, slow decrease in the gap. But it occurs to me that it might be due to race mixing! Ie, more white blood, but still counted as black. I don’t have any numbers, just a thought.

      • Mark Martinson

        I’ve also read that the Flynn effect is ending, at least in western countries.

      • Well, there has been a slow decrease if you start looking at around 1965. However, there was an increase in the B/W IQ gap from the 1910’s to the 1950’s, which is a period when the flynn effect was also occurring. So it has really been up and down over time while the flynn effect has been a fairly linear trend.

        Conveniently, from a rhetorical standpoint, the gap has gone up and down over the decades (a little, not a lot) but today the gap is roughly exactly what it was in the WW1 testing.

        • Mark Martinson

          With the dysgenic mating of blacks it’s unlikely to close and will probably increase. You know, there is nothing that the hereditarian perspective can’t explain. The environmentalists have to come up with an explantion for everything.

        • Sean Fielding

          1965, the year we dissidents often pick as the inflection point in the great decline (mainly because Immigration Act, but also acceleration in Civil Rights and start of hippy era). My guess is it also represents an inflection for miscegenation, If so, would support melonhead’s hypothesis

  • Mark Martinson

    Flynn denies the black/white IQ gap is genetic. Does he deny the Ashkenaiz Jewish/Aborigine gap is genetic?

    • melonhead

      He doesn’t deny that it /might be/, he just holds out the optimistic hope that it will prove to have some other, fixable cause. He’s said that the Flynn Effect leaves a crack open, something like that.

      • Mark Martinson

        I should have been more careful. Flynn has said (in his recent book) that it’s more likely than not that the black/white IQ gap is entirely environmental. Funny, no politician would say that.

      • BooBoo65

        I would suspect he is in the camp of thinking it’s best to not talk about it and he puts on the environmentalist front. I just can’t imagine any serious IQ researcher, with all the evidence we have, still thinking so much of it is related to the environment.

        There is a lot of pressure if you come out of the closet on that and he probably just doesn’t think it’s worth it.

        • Grey

          I just can’t imagine any person of actual intelligence taking IQ seriously unless it is noticeably below average.

  • Let’s say Flynn is right. The average black now is as intelligent as the average white in 1945. That’s supposed to show that the race difference in IQ is environmentally caused because there hasn’t been that much genetic change in the white population and the IQ has allegedly gone up 15 points. So, you can have a 15 point difference created by just an environmental change, no one knows why. Some think better nutrition or malnourished brain, etc. That’s also a fallacy. Just because a change in one group over time is due to an environmental change, doesn’t mean, or even make it probable, that a difference between 2 groups at the same time is due to an environmental change. The Flynn Effect make’s that highly unlikely and here’s why.

    The Flynn Effect, assuming it’s real, has been acting completely uniformly in every population. Any country you ask, the rate of increase is 3 per decade. That means it’s an environmental factor that affects whites and blacks the same way as well as the whole world. And as a result of this uniform environmental factor, you have a difference in IQ that’s being preserved. That would suggest that the response on the parts of blacks and whites is due to some non-environment factors, a genetic factor, which is making the difference in IQ remain constant as the Flynn Effect goes into effect.

    What makes it even more unlikely, in the last 60 years, their environments have become very similar since segregation. These differences don’t exist now, they go to the same schools by court order, same TV shows, same movies, basically same environment for both, and yet, that increasing similarity in the environment, the Flynn Effect, the IQ gap has remained intact. Which means whatever counts for the gap is genetic and not environmental. The more and more similar the environment, the less and less of the difference can be due to the environment and the more and more it must be due to genes. So this 15 point gap surviving these changes in the environment, seems more and more likely to be genetic in origin.

    So because this ‘Effect’ is the same across all populations and the gap didn’t close, that means it’s genetic. If the gap persisted even when IQs were rising 3 points per year, the B-W gap has still persisted, proving that it’s genetic.

    That is why the Flynn Effect is irrelevant. This “Effect”, has been a slight upward trend in IQ, around 3 points per decade, which, in my opinion, has to do with the advent of better nutrition and an industrialized society. The rise in IQ started around 1880, almost perfectly coinciding with the industrial revolution in America. Along with a more industrialized society, it’s possible to give most citizens in the country good enough nutrition to where they are not iodine deficient (adding iodine to our salt boosted Americans IQs), as well as being deficient in zinc, iron, protein and certain B vitamins which the effects of not getting enough leads to the brain not growing to its full potential, which in turn leads to a lower IQ.

    It’s also worth noting that the Flynn Effect is, mostly just better nutrition. Rushton also stated that the Flynn Effect wasn’t on the g factor.

  • Chaim Goldberg

    I’m confused by this part

    “For instance, “general processing speed” may be part of general
    intelligence and may help people add numbers. However, people who can
    generally think equally quickly may still differ in how fast they can

    People who think quickly differ on how fast they add? How? If they process at the same speed then the should add at the same speed.

    • It’s a poorly worded explanation of how intelligence subtests work.

    • “General processing speed” would refer to how quickly people think generally. People do not do all mental tasks with equal speed though, and for some people those neurological factors which contribute specifically to addition may be more efficient than they are for other people who generally preform mental tasks with the same speed as them.