Problems with Understanding IQ Testing and Your Common Psychologist

Snippets from an book review in the New Yorker regarding the perils of psychological tests for IQ, and the debates about the relationship of IQ to race.

One Saturday in November of 1984, James Flynn, a social scientist at the University of Otago, in New Zealand, received a large package in the mail. It was from a colleague in Utrecht, and it contained the results of I.Q. tests given to two generations of Dutch eighteen-year-olds.

When Flynn looked through the data, he found something puzzling. The Dutch eighteen-year-olds from the nineteen-eighties scored better than those who took the same tests in the nineteen-fifties—and not just slightly better, much better.

Curious, Flynn sent out some letters. He collected intelligence-test results from Europe, from North America, from Asia, and from the developing world, until he had data for almost thirty countries. In every case, the story was pretty much the same. I.Q.s around the world appeared to be rising by 0.3 points per year, or three points per decade, for as far back as the tests had been administered. For some reason, human beings seemed to be getting smarter.

Flynn has been writing about the implications of his findings—now known as the Flynn effect—for almost twenty-five years. His books consist of a series of plainly stated statistical observations, in support of deceptively modest conclusions, and the evidence in support of his original observation is now so overwhelming that the Flynn effect has moved from theory to fact.

What remains uncertain is how to make sense of the Flynn effect. If an American born in the nineteen-thirties has an I.Q. of 100, the Flynn effect says that his children will have I.Q.s of 108, and his grandchildren I.Q.s of close to 120—more than a standard deviation higher.

If we work in the opposite direction, the typical teen-ager of today, with an I.Q. of 100, would have had grandparents with average I.Q.s of 82—seemingly below the threshold necessary to graduate from high school.

And, if we go back even farther, the Flynn effect puts the average I.Q.s of the schoolchildren of 1900 at around 70, which is to suggest, bizarrely, that a century ago the United States was populated largely by people who today would be considered mentally retarded.

[...]

This is not a trivial issue. I.Q. tests are used to diagnose people as mentally retarded, with a score of 70 generally taken to be the cutoff. You can imagine how the Flynn effect plays havoc with that system. In the nineteen-seventies and eighties, most states used the WISC-R to make their mental-retardation diagnoses. But since kids—even kids with disabilities—score a little higher every year, the number of children whose scores fell below 70 declined steadily through the end of the eighties.

Then, in 1991, the WISC III was introduced, and suddenly the percentage of kids labelled retarded went up. The psychologists Tomoe Kanaya, Matthew Scullin, and Stephen Ceci estimated that, if every state had switched to the WISC III right away, the number of Americans labelled mentally retarded should have doubled.

That is an extraordinary number. The diagnosis of mental disability is one of the most stigmatizing of all educational and occupational classifications—and yet, apparently, the chances of being burdened with that label are in no small degree a function of the point, in the life cycle of the WISC, at which a child happens to sit for his evaluation. “As far as I can determine, no clinical or school psychologists using the WISC over the relevant 25 years noticed that its criterion of mental retardation became more lenient over time,” Flynn wrote, in a 2000 paper. “Yet no one drew the obvious moral about psychologists in the field: They simply were not making any systematic assessment of the I.Q. criterion for mental retardation.”

Fortunately Flynn is able to cut through a lot of the BS that is associated with the field, when it comes to debates like IQ vs Race.

Two weeks ago, Flynn came to Manhattan to debate Charles Murray at a forum sponsored by the Manhattan Institute. Their subject was the black-white I.Q. gap in America. During the twenty-five years after the Second World War, that gap closed considerably. The I.Q.s of white Americans rose, as part of the general worldwide Flynn effect, but the I.Q.s of black Americans rose faster. Then, for about a period of twenty-five years, that trend stalled—and the question was why.

Murray showed a series of PowerPoint slides, each representing different statistical formulations of the I.Q. gap. He appeared to be pessimistic that the racial difference would narrow in the future. “By the nineteen-seventies, you had gotten most of the juice out of the environment that you were going to get,” he said. That gap, he seemed to think, reflected some inherent difference between the races. “Starting in the nineteen-seventies, to put it very crudely, you had a higher proportion of black kids being born to really dumb mothers,” he said.

When the debate’s moderator, Jane Waldfogel, informed him that the most recent data showed that the race gap had begun to close again, Murray seemed unimpressed, as if the possibility that blacks could ever make further progress was inconceivable.

Flynn took a different approach. The black-white gap, he pointed out, differs dramatically by age. He noted that the tests we have for measuring the cognitive functioning of infants, though admittedly crude, show the races to be almost the same. By age four, the average black I.Q. is 95.4—only four and a half points behind the average white I.Q. Then the real gap emerges: from age four through twenty-four, blacks lose six-tenths of a point a year, until their scores settle at 83.4.

That steady decline, Flynn said, did not resemble the usual pattern of genetic influence. Instead, it was exactly what you would expect, given the disparate cognitive environments that whites and blacks encounter as they grow older.

Black children are more likely to be raised in single-parent homes than are white children—and single-parent homes are less cognitively complex than two-parent homes. The average I.Q. of first-grade students in schools that blacks attend is 95, which means that “kids who want to be above average don’t have to aim as high.”

There were possibly adverse differences between black teen-age culture and white teen-age culture, and an enormous number of young black men are in jail—which is hardly the kind of environment in which someone would learn to put on scientific spectacles.

Flynn then talked about what we’ve learned from studies of adoption and mixed-race children—and that evidence didn’t fit a genetic model, either.

If I.Q. is innate, it shouldn’t make a difference whether it’s a mixed-race child’s mother or father who is black.

But it does: children with a white mother and a black father have an eight-point I.Q. advantage over those with a black mother and a white father.

And it shouldn’t make much of a difference where a mixed-race child is born.

But, again, it does: the children fathered by black American G.I.s in postwar Germany and brought up by their German mothers have the same I.Q.s as the children of white American G.I.s and German mothers.

The difference, in that case, was not the fact of the children’s blackness, as a fundamentalist would say. It was the fact of their Germanness—of their being brought up in a different culture, under different circumstances.

“The mind is much more like a muscle than we’ve ever realized,” Flynn said. “It needs to get cognitive exercise. It’s not some piece of clay on which you put an indelible mark.”

The lesson to be drawn from black and white differences was the same as the lesson from the Netherlands years ago: I.Q. measures not just the quality of a person’s mind but the quality of the world that person lives in.

And of course, these results also mean that a person's IQ is changeable, given enough time, proper environment, education, and other therapeutic methods.