Brainier kids have longer critical-learning period

By Clay Evans



John Hewitt was bemused, though perhaps not surprised, that one of the first emails he received in response to a September NPR story about his recent work showing the surprising importance of environment to some adolescent learners was from a private school in Denver, asking him to speak.

“That’s exactly what they would love to hear,” says Hewitt, director of the Institute for Behavioral Genetics at CU-Boulder, “that it’s worth investing money for the best environment for your kid.”

In truth, the findings published as “The Nature and Nurture of High IQ: An Extended Sensitive Period for Intellectual Development” in Psychological Science with 12 co-authors, took the father of four by surprise. After all, there is plenty of research — and even more real-world experience — to suggest that children of intelligent parents are themselves likely to be intelligent, regardless of environment.

“I never worried too much about how (my children) were going to get on, because intelligence is determined more by genes than environment. I just took a more relaxed view,” Hewitt says.

But he acknowledges that the new research, gleaned from data gathered on identical and paternal twins, siblings and adopted siblings over nearly four decades, “suggests that I have been to some extent wrong. There may really be a critical period of development when giving an extra boost, especially to high-IQ individuals, may make a difference.”



Hewitt credits Angela Brant, who recently earned her doctorate from CU-Boulder and now is a post-doctoral fellow at the Pennsylvania State University, with posing the question that led to the study.

Generally speaking, children are better than adults at learning, and the older a child grows, the less responsive his or her brain is to certain kinds of information. There is a “sensitive” period of learning that tapers off from childhood to adolescence to adulthood. However, the new research indicates an extended period of receptiveness to learning for some children, most notably those who already have higher IQs.

“Or another way of looking at it is the sensitivity to the environment which is characteristic of earlier childhood seemed to end earlier for individuals with lower IQ,” Hewitt said in the NPR story, broadcast on Sept. 25.

And that means, he says, “if as a family you place higher value on achievement, it may well be that making those extra efforts to maximize achievement at important points in a child’s development may be worthwhile.” Hence the enthusiasm of private schools, which perhaps rightly have seen the research as leverage to promote their programs as an ideal learning environment at a critical point in a child’s development. To boot, purveyors of, say, extracurricular music and language training now have an additional marketing point.

The study points — as studies are wont to do — to further questions, particularly regarding the mechanisms for extended learning in intelligent children. It could be, Hewitt says, that they are more driven to take up challenges, or just as easily, the genes governing IQ could also be associated with extended learning.

Hewitt notes that none of the research would be possible without the continual collection of data across many decades.

“We’ve studied some subjects from birth into their mid-20s, or even longer than that. When you can gather information repeatedly on the same individual over a 25-year period, it gives us the ability to ask all sorts of interesting questions for research,” he says.

But the payoff for such research is seldom short-term, which means that public funding through public sources such as the National Institutes of Health is critical.

“And part of our mission is not only doing the research, but training biomedical researchers for the future,” he says.

For all the implications of the new research, Hewitt doesn’t foresee changing his own approach to parenting.

“I have other values,” he says nonchalantly. “I think things will work out without agonizing over how my children spend every hour of the day. I just don’t think I’d send my kid to extra classes to give him an extra IQ point or two.”

December 2013