School smart: IQ and the teenage brain

A story that made the rounds this week (I wrote about it for COSMOS, but it went as big as the BBC) was the UCL study that linked IQ swings in adolescence to specific structural changes in the brain.

Whenever a science story goes viral, there is always either a miscommunication, misunderstanding or misplaced emphasis. For this one, it's misplaced emphasis. Take, for example, the BBC piece, which suggests the most significant aspect of the study to be the fact that it demonstrated IQ fluctuation. Any psychologist who studies intelligence will tell you that we've known about this for years. Rather, what's exciting about the UCL study is its neuroscientific (rather than psychological) finding: namely, that there is a significant correlation with particular structural changes in the brain - which they were able to isolate and observe - and verbal and non-verbal IQ.

For the COSMOS piece, I talked with Prof Stephen Ceci, an influential developmental psychologist at Cornell, about the results. I found he situated the study well, and asked some interesting questions. Because you have to be choosy in a news article, I thought to include two of his longer comments on the blog. Voila.

How does this UCL study change what we already knew?

We have known for a very long time that intelligence can be quite volatile. All one needs to do is look at what happens when a child ceases to attend school. If you take two adolescents who have identical IQ scores and allow one to drop out school while the other continues to finish high school or gymnasium, we witness a very large IQ difference as young adults. Specifically, the individual who dropped out of school will lose anywhere between 2 and 5 IQ points for every year short of finishing school. That's a huge decrement! And there are many studies which have documented such systematic changes in intelligence in response to changes in the environment, such as school termination, early adoption, etc. (my 1996 book, "On intelligence...a bioecological treatise on intellectual development", reviewed much of this evidence). So volatility in intelligence is well documented. Many have dismissed such changes as "measurement error", meaning that the IQ test is not perfectly reliable so some fluctuation is to be expected even if the underlying trait (general intelligence) is highly stable across the lifecourse. In a way, Ramsden et al give the lie to this dismissal by showing that the IQ changes are in lockstep with specific brain changes, suggesting that the former are not measurement noise but rather neural sequelae. But no one knows what is driving these twin changes in IQ and neural density. We have no idea if genes are being turned on and off in response to biological maturation in conjunction with environmental changes. The bio-ecological framework that some of us work from would point to possible clues in the environment that interact with genetic potential for spatial and verbal performance, but this is mere surmose. Future research will need to involve large, diverse samples followed over time that can be disaggregated along various types of environmental changes.

We tend to have a sense of ourselves as continuous--we are the same person we were last year. Our sense of self is predicated on such continuity. However, these findings suggest that for some of us this sense of continuity may be less salient than for others. Specifically, one wonders whether adolescents who experienced massive fluctuations in their cognitive profile (e.g., a 20-point verbal or performance IQ decline over a 4-year period) have a sense of self that is less continuous than an adolescent whose verbal and performance scores changed relatively little over these years. Imagine going from being slightly above average in your able to solve puzzles, matrices, mazes, etc. to being decidedly below average! In some sense we are not the same person we once were; we may transition from regular education where we kept pace with classmates to being in need of intensive tutoring, perhaps special education services. For me, this is the most interesting implication of this study, and it will be very important to see whether the documented changes in brain structure and cognitive abilities are linked to changes in how these adolescents perceive themselves. One wonders, for example, if the adolescents who exhibited the largest declines in cognitive abilities and concomitant brain changes also exhibited the most problems in social and emotional development, as might happen if our sense of self was disrupted.

On another note, I spent a good 20 minutes trying to create a new portmanteau word for the title of this post. Not recommended.

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Ramsden et al., Verbal and non-verbal intelligence changes in the teenage brain, Nature (2011).