While the debate over intelligence rages on many fronts, the battle over the importance of heredity rages loudest. It’s easy to see why. If the camp that argues intelligence is 75 to 85 percent genetically determined is correct, then we’re faced with some tough questions about the role of education. If intelligence is improved very little by schools, and if the IQ of the majority of the population will remain relatively unchanged no matter how well schools perform, then should school reform really be a priority?
More to the point, if our genes largely determine our IQ, which in turn underlies our performance throughout our lives, then what is the role of school? For some in this debate the answer to that question is simply, “to be the best you can be.” But that seems little comfort for those who aspire to “be” more than what their IQ category predicts they will.
Those on the other side of this debate question whether heredity plays as big a role as the strong hereditarians claim. And for the role it does play, they question whether hereditability implies immutability. Heredity of height, for example, is about 90 percent, and yet average height in several populations around the world has been steadily increasing due to non-genetic influences, like nutrition. If such a strong hereditary trait can be radically altered by environmental factors–and height is but one example of this–then why is intelligence different?
It is not, argues the camp that might best be described as intelligence optimists. For them, the pessimism that colors the strong hereditarian position isn’t only discouraging, it’s dangerous. Too much is hanging in the balance for pessimism about the potential of our children to prevail.
Richard Nisbett is a champion of the intelligence optimist camp, and with his latest book, Intelligence and How to Get It, he has emerged as the most persuasive voice marshalling evidence to disprove the heredity-is-destiny argument. Intellectual advancement, Nisbett argues, is not the result of hardwired genetic codes, but the province of controllable factors like schools and social environments–and as such, improving these factors is crucially important. In the thick of controversy, he was gracious enough to spend a few minutes discussing his book with Neuronarrative.
In Intelligence and How to Get It, you counter the arguments of strong intelligence hereditarianism, but in a sense you’re countering heritability dogma overall. What led you to take on this challenge?
My only complaint was with the heritability of intelligence per se. I just had the strong intuition that intelligence, and certainly IQ scores, were heavily influenced by the environment and by gene-environment interactions. My research indicates that in fact heritability, especially for adult IQ, is substantially less than frequently assumed.
One of the topics you discuss in the book is that drawing inferences based on correlations often produces misleading results. What’s an example of this in the case of intelligence?
The correlation between identical twins reared apart gives an overestimate of heritability because the environments of identical twins reared apart are often highly similar. But the main contradiction of heritability estimates lies in the fact that adoption produces a huge effect on IQ – much bigger than could be explained if you believed the conclusion of heritability estimates based on sibling correlations.
You discuss the importance of early childhood education and provide some compelling statistics on the IQ-boosting effects of preschool. Why in a nutshell is early education so essential?
This is speculative at this point, but here goes. It is beginning to look like the IQ deficits of poor minority kids begin extremely early and have to do with rearing techniques. Parents of such kids don’t talk to them much and don’t do things that would stimulate intelligence. At any rate, we know of several socialization practices that correlate substantially with IQ, and for all those practices parents of poor minority kids are on the low side.
If a child doesn’t receive quality early education, will he or she still be able to bridge the gap later on?
We do know that interventions as late as early adulthood can have a big effect on IQ and academic achievement. College reduces the IQ gap between blacks and whites from one standard deviation (SD) to .4 SD. Just telling junior high school kids that their intelligence is under their control can produce a gain in GPA. You can put a great deal of educational effort in at middle school and junior high ages and produce marked IQ and academic achievement gains.
You mention that children with greater self-control tend to have higher intelligence. How are these linked, and is it reasonable to conclude that increasing self-control raises intelligence?
This is speculative. We know there is a correlation between self-control and intelligence, especially between self-control and both ACT achievement and SAT scores. What we don’t know is whether this relationship is causal. I don’t doubt that it is, but I can’t prove it.
We now know that the brain isn’t a static entity, but rather possesses remarkable plasticity – even, to a degree, well into adulthood. In light of this, and your own research, is it possible for adults to still boost their IQs?
We know that you can increase fluid intelligence even in adults by some kinds of computer-game-like programs. But that work is in its infancy. We know also that the hippocampi of London taxi drivers is 25 percent larger than normal – due to an increase in the spatial relations requirements of the job.
I took away the sense from reading the book that you’re a hopeful realist. If we could begin making changes to our educational system today, what do you think are the most important things we can do to create a brighter future for our kids?
Really effective intervention with parents of low socioeconomic status infants to help them with socialization practices, really good pre-K, KIPP-type elementary and middle school.
I am hopeful, for sure. In principle you could have all these things for the bottom third of socioeconomic status families for less per year than the bailout of AIG. But I hasten to say that we don’t really know how well any of the programs shown to be effective in demonstration projects would scale up.