The Achievement Gap and The Brain

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.


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In my opinion, these concerns are what public intellectuals ought to be talking about (and yes, I'm referencing your lament yesterday about the present state of public intellectualism). I tell my cognitive psych students that what we study has enormous potential to have an impact on people's quality of life; that issues of development and differential behavior and acheivement are where "the rubber meets the road." Martha Farah's work is also important (although it was a small sample) in understanding the debilitating effects of poverty on the devloping brain, and you are certainly right to point out that poverty is stress!

But hey, if Steven Johnson is right, we all just need to watch some of those complex TV programs like Lost and play a little Sims and all will be right with the world.

Thank you for this powerful post. You have a very important message here.

While making repeat visits to a relative in a hospital recently, I noticed several times a family with a little boy who was probably two. I also noticed the family, parents and a couple of teenagers, never seemed to speak to the child. Finding myself on the elevator alone with them, I watched the child staring at the buttons and reaching out timidly to touch them. I turned to the parents and said, "Look how interested your little boy is in how the elevator works. That's a sign of intelligent curiosity. It would be good for you to explain to him what the buttons are for, and maybe next time let him be the one to push the button for the correct floor. Talk to him about it. I'll bet he'd learn a lot." The parents just stared, and didn't respond, but the teenage boy explained, in a voice that suggested I must be very ignorant, "He can't talk yet, so there's no point in saying anything to him."

There's got to be some way to educate parents about this. Perhaps we can find a way to teach young people in middle school and high school that they ought to talk as much as possible, in a kind and encouraging way, to the younger children in their families and to their own children later on.

Neither you nor the New York Times address the genetic component of the achievement gap. The New York Times has solid reasons for not addressing the role genes play in differiental outcomes: if they did, it would be tantamont to admitting that their editorial line was wrong for the last fifty years. It would be a severe blow to their credibility.
Don't become out of those people who lie all the time about racial differences being all environment. It gets old fast.

By commenter (not verified) on 28 Nov 2006 #permalink


I don't believe you read the New York Times article carefully. What it was discussing is ways to improve education of the so-called permanent underclass, the very individuals you seem to believe are incapable of learning. You also disregard the very important research, mentioned in the article, showing that self-discipline is more important than IQ in explaining differences in achievement.

Further, there is a wide body of research, not discussed here, but certainly in other NYT articles, demonstrating that IQ can in fact be increased through education. This article shows that student achievement, but not specifically IQ, can be improved through effective teaching, especially teaching that focuses on self-discipline.

You may prefer to throw up your hands and claim "it's just genetics," but I'd much rather try to figure out how to give everyone a truly equal education, then see how much they can achieve.

It's not surprising that racist polemics - complete with the sort of misspelling indicative of inferior education - get old really quickly. Tiresome, as this twaddle one sees from ignorant, racist commenters was old 200 years ago.

No doubt some people pick up discarded copies of The Bell Curve and think they've found the Holy Grail.

Pitiful, really.

A Manhattanite.

By TaurusNYC (not verified) on 28 Nov 2006 #permalink

For the welfare children, the situation was reversed: they heard, on average, about 75,000 encouragements and 200,000 discouragements.

That's a major stressor.

By natural cynic (not verified) on 28 Nov 2006 #permalink

Very good post.

2 links of interest:

- On the role of stress and stress management programs starting to be used at schools

- On working memory training (that has been shown to increase IQ by 8% and be veru helpful for kids with ADD/ ADHD and normal college students, but not published data yet on academic impact)…

Like Dave and Jonah, I do not neglect the role of genetics but, given I cannot do anything to change that, prefer to focus on training and educational interventions.

This has been looked at before-- I can't remember the darned cite, but I recall reading about a longitudinal study of Socioeconomic status and mental health. The researches were handed a windfall, as a subset of their subjects were native american, and during the course of the the study a casino was built and wealth increased substantially for the whole tribe. I distinctly remember that incidences of depression, and a few other mental illnesses went down significantly relative to the other groups who remained in poverty, and I believe there was also a gain in some measures of academic achievement. Anyone else know this study?

The stress factor is definitely interesting and I think I'm going to look it up and read more.

But just wanted to throw this off the top of my head: what the animals in those stress experiments were subjected to, would, in its human equivalent, be something more along the lines of a child, growing up with a war raging around him, no? (I know I'm oversimplifying but still...). What degree of povery would be equivalent? And at what degree of poverty would stress blot out all other factors that influence a child's capability to be successful in today's world?

One of my observations is that people who come from poorer backgrounds tend to be much more resourceful at certain tasks -- perhaps stress helps them become more resourceful? Again, the question becomes, what level of stress is acceptable? Seems like this could help us find a cut-off poverty line for a welfare state -- I wonder, is there any research on this out there?

I believe that impoverished (and wealthy) environments are an extended phenotype of the individuals that populate them. I agree with commenter's remarks, and think that the genetic contribution to intelligence and self-discipline is extremely important. There is a great deal of evidence from non-human primate research showing that impulse control is regulated by the expression of dopamine and serotonin transporter genes. See:

Higley JD, Linnoila M.Low central nervous system serotonergic activity is traitlike and correlates with impulsive behavior. A nonhuman primate model investigating genetic and environmental influences on neurotransmission.
Ann N Y Acad Sci. 1997 Dec 29;836:39-56. Review.

And the high heritability of g is beyond dispute at this point. The work of Robert Plomin is a good place to start; see for example:

Br J Educ Psychol. 2004 Sep;74(Pt 3):323-42.
Nature, nurture and academic achievement: a twin study of teacher assessments of 7-year-olds.

Walker SO,
Petrill SA,
Spinath FM,
Plomin R.
Social, Genetic and Developmental Psychiatry Research Centre, Institute of Psychiatry, King's College, London, UK.
BACKGROUND: Twin research has consistently shown substantial genetic influence on individual differences in cognitive ability; however, much less is known about the genetic and environmental aetiologies of school achievement. AIMS: Our goal is to test the hypotheses that teacher-assessed achievement in the early school years shows substantial genetic influence but only modest shared environmental influence when children are assessed by the same teachers and by different teachers. SAMPLE: 1,189 monozygotic (MZ) and dizygotic (DZ) twin pairs born in 1994 in England and Wales. METHODS: Teachers evaluated academic achievement for 7-year-olds in Mathematics and English. Results were based on the twin method, which compares the similarity between identical and fraternal twins. RESULTS: Suggested substantial genetic influence in that identical twins were almost twice as similar as fraternal twins when compared on teacher assessments for Mathematics, English and a total score. CONCLUSIONS: The results confirm prior research suggesting that teacher assessments of academic achievement are substantially influenced by genetics. This finding holds even when twins are assessed independently by different teachers.

By doublehelix (not verified) on 30 Nov 2006 #permalink

Jonah said--

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.

Yeah, and you both simply ignore the obvious elephant in the room. Quite remarkable that.

What might be, and more than 40 years of the best research by psychologists largely hostile to this idea strongly suggests is, the MOST potent variable is a significant average genetically influenced difference in innate IQ potential between Africans on the one hand, and Europeans and Asians on the other.

Cultural differences are also important, in the same way that training and exercise are important to fully develop innate abilities for both those with great athletic potential (who are disproportionately black) and those with lesser amounts of those innate abilities.

A host of things, including societal messages blaming most problems of differential achievement on the larger society and white racism rather than sufficiently emphasizing the need for black self help, self reliance, and cultural reform (especially among the lower SE half) could be changed and could help reduce the gap which genetic differences are likely to prevent from being entirely closed.

Of course there's also a great need for improvement in the levels of attainment and self discipline expected of white kids in public schools, especially of middle middle, and lower middle class white kids whose parents often aren't pushing as hard as those of the upper middle class. There's considerable reason to suspect that this has been a greatly neglected area, as most elite ed school (e.g. Stanford) and other societal efforts have focused almost entirely on eliminating or at least reducing the black /white academic achievement gap.

By djexplorer (not verified) on 30 Nov 2006 #permalink


It's not surprising that racist polemics -

Racist, racist, racist!!!

Shut down thought and certainly any discussion that admits of the possibility of significant innate racial difference immediately!!! It's just too horrible to bear considering!!!

I've not seen racist polemics here, if by that you mean bigoted demeaning of racial groups based on preconceptions.

If what you mean by racism is any recognition that scientific evidence including but hardly limited to very telling twin studies, suggests that there are in fact differences in both innate endowment (genes influencing IQ) and socially developed cultures between some populations (or races or ethnicities), then yes, that there's been. For SHAME!!

As of course there has to be, if honesty and science are of any importance, instead of only dogma and ideological purity. This isn't the Stalinist Soviet Union, is it? Is it (in these PC taboo areas)??

Of course what I really suspect you mean is that the genetic basis of intelligence differences truth shouldn't be studied as much as the PC can manage, or at least MUST not be talked about or even considered when formulating the actually most effective way of stimulating black academic, and economic, achievement.

The point isn't to throw up our hands and give up on those with less intelligence, many (only a somewhat lower percentage) of whom are of course also white and Asian. The point is to work hard to both tailor education differently for different demonstrated ability levels in order to do the most to develop potential and confer useful skills rather than only academic failure. The point is also to work to change cultural factors which tend to make black school achievement considerably worse than it need be, even after accepting that there's almost certainly an average genetic difference.

By djexplorer (not verified) on 30 Nov 2006 #permalink

Dave Munger--

Further, there is a wide body of research, not discussed here, but certainly in other NYT articles, demonstrating that IQ can in fact be increased through education.

Care to elaborate?

By djexplorer (not verified) on 30 Nov 2006 #permalink