The Frontal Cortex

There's a thorough article in the Times Magazine on the persistence of the "achievment gap" in public education. The conclusion of the article is rather simple: the "achievment gap" persists due to a series of entrenched inequalities, but very good schools (and I mean very good) can actually compensate for a lot of these disadvantages. The problem, of course, is creating very good schools.

So read the whole article, if you're interested in why only 13 percent of black eighth-grade students are "proficient" in reading. I was most interested in the parts of the article that dealt with the psychology of poverty, since most of the research suggests that the "achievement gap" has real neurological roots, which are caused by distinct home environments:

Researchers began peering deep into American homes, studying up close the interactions between parents and children. The first scholars to emerge with a specific culprit in hand were Betty Hart and Todd R. Risley, child psychologists at the University of Kansas, who in 1995 published the results of an intensive research project on language acquisition. Ten years earlier, they recruited 42 families with newborn children in Kansas City, and for the following three years they visited each family once a month, recording absolutely everything that occurred between the child and the parent or parents. The researchers then transcribed each encounter and analyzed each child's language development and each parent's communication style. They found, first, that vocabulary growth differed sharply by class and that the gap between the classes opened early. By age 3, children whose parents were professionals had vocabularies of about 1,100 words, and children whose parents were on welfare had vocabularies of about 525 words. The children's I.Q.'s correlated closely to their vocabularies. The average I.Q. among the professional children was 117, and the welfare children had an average I.Q. of 79.

When Hart and Risley then addressed the question of just what caused those variations, the answer they arrived at was startling. By comparing the vocabulary scores with their observations of each child's home life, they were able to conclude that the size of each child's vocabulary correlated most closely to one simple factor: the number of words the parents spoke to the child. That varied greatly across the homes they visited, and again, it varied by class. In the professional homes, parents directed an average of 487 "utterances" -- anything from a one-word command to a full soliloquy -- to their children each hour. In welfare homes, the children heard 178 utterances per hour.

What's more, the kinds of words and statements that children heard varied by class. The most basic difference was in the number of "discouragements" a child heard -- prohibitions and words of disapproval -- compared with the number of encouragements, or words of praise and approval. By age 3, the average child of a professional heard about 500,000 encouragements and 80,000 discouragements. For the welfare children, the situation was reversed: they heard, on average, about 75,000 encouragements and 200,000 discouragements. Hart and Risley found that as the number of words a child heard increased, the complexity of that language increased as well. As conversation moved beyond simple instructions, it blossomed into discussions of the past and future, of feelings, of abstractions, of the way one thing causes another -- all of which stimulated intellectual development.

Hart and Risley showed that language exposure in early childhood correlated strongly with I.Q. and academic success later on in a child's life.

This is really important research, but I can't help but think that part of the equation is missing. While Paul Tough, author of the Times article, focuses on gaps in environmental enrichment - poor kids are exposed to fewer words, have less stimulating conversations, etc. - he ignores what might be an even more potent variable: stress.

As I noted in a profile of Elizabeth Gould:

From the brain's perspective, stress is primarily signaled by an increase in the bloodstream of a class of steroid called glucocorticoids, which put the body on a heightened state of alert. But glucocorticoids can have one nasty side-effect: They are toxic for the brain. When stress becomes chronic, neurons stop investing in themselves. Neurogenesis ceases. Dendrites disappear. The hippocampus, a part of the brain essential for learning and memory, begins withering away.

Gould's insight was that understanding how stress damages the brain could illuminate the general mechanisms--especially neurogenesis--by which the brain is affected by its environ-mental conditions. For the last several years, she and her post-doc, Mirescu, have been depriving newborn rats of their mother for either 15 minutes or three hours a day. For an infant rat, there is nothing more stressful. Earlier studies had shown that even after these rats become adults, the effects of their developmental deprivation linger: They never learn how to deal with stress. "Normal rats can turn off their glucocorticoid system relatively quickly," Mirescu says. "They can recover from the stress response. But these deprived rats can't do that. It's as if they are missing the 'off' switch."

Gould and Mirescu's disruption led to a dramatic decrease in neurogenesis in their rats' adult brains. The temporary trauma of childhood lingered on as a permanent reduction in the number of new cells in the hippocampus. The rat might have forgotten its pain, but its brain never did. "This is a potentially very important topic," Gould says. "When you look at all these different stress disorders, such as PTSD [post-traumatic stress disorder], what you realize is that some people are more vulnerable. They are at increased risk. This might be one of the reasons why."

Subsequent experiments have teased out a host of other ways stress can damage the developing brain. For example, if a pregnant rhesus monkey is forced to endure stressful conditions--like being startled by a blaring horn for 10 minutes a day--her children are born with reduced neurogenesis, even if they never actually experience stress once born. This pre-natal trauma, just like trauma endured in infancy, has life-long implications. The offspring of monkeys stressed during pregnancy have smaller hippocampi, suffer from elevated levels of glucocorticoids and display all the classical symptoms of anxiety. Being low in a dominance hierarchy also suppresses neurogenesis. So does living in a bare environment. As a general rule of thumb, a rough life--especially a rough start to life--strongly correlates with lower levels of fresh cells.

"Poverty is stress," Gould says, with more than a little passion in her voice. "One thing that always strikes me is that when you ask Americans why the poor are poor, they always say it's because they don't work hard enough, or don't want to do better. They act like poverty is a character issue."

Gould's work implies that the symptoms of poverty are not simply states of mind; they actually warp the mind. Because neurons are designed to reflect their circumstances, not to rise above them, the monotonous stress of living in a slum literally limits the brain.

I think a complete understanding of the "achievement gap" will only come when we investigate these two variables in tandem. When chronic stress is coupled with less stimulating environments, the result can be crippling.