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Brains and Economic Inequality

Psychologists have known for years now that educational achievement is associated with life chances. Better students go to better colleges and universities, get better jobs, make more money and generally live longer and more satisfying lives. It is good to be educated.

We’ve also known that there are strong correlations between socio-economic status (SES) and educational success. Students who come from more economically and socially successful families have higher overall academic performance. It’s good to have well-off parents.

These effects are all part of the “income - achievement gap.” Persons from the higher SES groups outperform those from the lower segments on a wide range of factors. This (in)famous gap has been studied by psychologists, sociologists, health professionals, demographers, economists and political scientists for decades. A lot is known about it, particularly the economic, life-satisfaction and health issues — and in all of them, folks from higher SES groups do better.

A paper, from John Gabrieli’s lab at MIT just appeared in the prestigious journal Psychological Science that adds a neurological variable to this picture. The higher SES students, it turns out, have different brains! The MIT researchers found that the thickness of the cerebral cortex was strongly correlated with SES. And it wasn’t merely changes in specific parts of the cortex. It was found throughout gray matter. The more money your folks have the thicker your cortex and, other things being equal, having more cortical cells is correlated with better academic performance.

The authors were careful to point out some important aspects of these findings. First, they are correlations and correlations do not necessarily identify the causes. One can think of a number of plausible or semi-plausible alternate interpretations of these findings.

For example, it’s possible that the students from the higher SES families were biologically prepared for thicker cortices. They might have inherited them from their parents in which case these correlations simply reflect a genetic factor. This is, however, known to be incorrect. Developmental studies show that the increase in neurocortical development is acquired; everyone starts out pretty much the same (baring congenital disorders).

It is also possible that there are racial or ethnic factors operating. When large samples are analyzed, Black and Hispanic Americans perform more poorly in school than Whites and also have lower SES scores. Hence, one might argue that it’s race and ethnicity that are the causes of these correlations.

Again, when these factors were controlled for, the effects remained the same. Black and Hispanic students from high SES families show the same increased cortical growth as Whites. It’s SES that counts here.

The big question is what’s going on? What’s causing this differential cortical development? Are there ameliorative programs? And, importantly, what are its long-term social and economic consequences?

The tentative answer to the first is that the primary cause is the life-stresses that accompany poverty. Continued stress, particularly during early life, is known to interfere with neurocortical development. The mechanisms are many and complex but, as the authors put it, “… enhanced exposure to stress and reduced environmental enrichment” are the likely causes.

There are interventions that can mitigate the problem — and starting early in life is better than waiting. Neuroanatomy is modifiable through experience. Many studies have revealed changes after only a few weeks of specialized learning programs. Optimally these should be introduced into primary and secondary schools and focus on the students from economically disadvantaged backgrounds.

Do I expect to see this happen? No, not in this political climate. The broad canvas on which this study should be viewed is a worrisome one. With increasing inequality in the country we are going to see further increases in inequality. It’s a terrible end that feeds itself.

This study shows us what the real culprit is and it’s not a lack of values or low motivation or any of the other bizarre notions tossed out by the right. It’s poverty itself. It knows no race, no ethnicity. It’s self-perpetuating and has, alarmingly, clear implications for cognitive function, academic success and all that follows.

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