Home » IQ » “Differences in brain structure development may explain test score gap for poor children” Maybe not….

“Differences in brain structure development may explain test score gap for poor children” Maybe not….

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JP Rushton

Richard Lynn

L:inda Gottfredson


1500 words

Summary: They would have to explain why whites in poorer families score higher than blacks in all other income brackets except blacks in families making over 200,000 dollars per year, which even then blacks only score 3 points higher in the 200,000 dollar plus per year income bracket. They say that frontal and temporal lobes are smaller in poorer children, which whites have bigger frontal and temporal lobes on average as well as having more activity in the frontal lobes, which is thought to be the seat of intelligence. Blacks having smaller brains than whites on average explains the size differences between the differences in the different parts of the brain mentioned.

Low-income children had atypical structural brain development and lower standardized test scores, with as much as an estimated 20 percent in the achievement gap explained by development lags in the frontal and temporal lobes of the brain, according to an article published online by JAMA Pediatrics.

If true, only 20 percent of the achievement gap affected by poverty. I doubt it seeing as poor whites in families making less than 20,000 dollars a year still have 180 points over blacks in the same income bracket and blacks in families making more than 200,000 dollars per year have a 981 score, only 3 points higher than whites in families making less than 20,000 dollars per year. Whites in families making less than 20,000 dollars per year still outperform all negro families in all other income brackets except in negro families making over 200,000 dollars per year by only 3 points. Not even worth talking about.

20 percent of the achievement gap is apparently explained by developmental lags in the front and temporal lobes of the brain. Blacks have a smaller PFC (prefrontal cortex) which may explain it.

Socioeconomic disparities in school readiness and academic performance are well documented but little is known about the mechanisms underlying the influence of poverty on children’s learning and achievement.

It’s well documented that even in poor whites and poor blacks, poor whites are still on average more intelligent and have higher standardized test scores than do blacks.

Seth D. Pollak, Ph.D., of the University of Wisconsin-Madison, and colleagues analyzed magnetic resonance imaging (MRI) scans of 389 typically developing children and adolescents ages 4 to 22 with complete sociodemographic and neuroimaging data. The authors measured children’s scores on cognitive and academic achievement tests and brain tissue, including gray matter of the total brain, frontal lobe, temporal lobe and hippocampus.

I wonder what the breakdown was. Will revise when the full paper comes out. Hippocampal differences are also explained by whites having larger brains than blacks as well as the other parts they state.

The authors found regional gray matter volumes in the brains of children below 150 percent of the federal poverty level to be 3 to 4 percentage points below the developmental norm, while the gap was larger at 8 to 10 percentage points for children below the federal poverty level. On average, children from low-income households scored four to seven points lower on standardized tests, according to the results. The authors estimate as much as 20 percent of the gap in test scores could be explained by developmental lags in the frontal and temporal lobes.

On frontal lobes from this Rushton paper decimating Gould’s garbage *Mismeasure of Man*, which also states they have smaller frontal lobes than whites:

“Bean also reported that the 103 Negro brains were less convoluted than were 49 White brains and that Whites had a proportionately larger genus to splenium ratio (front to back part of corpus callosum), implying that Whites may have more activity in the frontal lobes which were thought to be the seat of intelligence. Consider the following statistically significant comparisons (sexes combined) from recently conducted studies using the four techniques mentioned above. Using brain mass at autopsy, Ho et al. (1990) summarized data for 1,261 individuals. They reported a mean brain weight of 1,323 grams for White Americans and 1,223 grams for Black Americans. Using endocranial volume, Beals et al. (1984) analyzed about 20,000 skulls from around the world and found that East Asians, Europeans, and Africans averaged cranial volumes of 1,415, 1,362, and 1,268 cm3 respectively. Using external head measurements from a stratified random sample of 6,325 U.S. Army personnel, Rushton (1992) found that Asian Americans, European Americans, and African Americans averaged 1,416, 1,380, and 1,359 cm3, respectively. Using external head measures from tens of thousands of men and women from around the world collated by the International Labour Office, Rushton (1994) found that Asians, Europeans, and Africans averaged 1,308, 1,297, and 1,241 cm3, respectively. Finally, an MRI study in Britain found that people of African and of Caribbean background averaged a smaller brain volume than did those of European background (Harvey et al., 1994). Contrary to most purely environmental theories, racial differences in brain size show up early in life. Data from the U.S. National Collaborative Perinatal Project on 19,000 Black children and 17,000 White children showed that Black children had a smaller head perimeter at birth and, although Black children were born shorter in stature and lighter in weight than White children, by age 7 ‘catch-up growth’ led Black children to be larger in body size than White children. However, Blacks remained smaller in head perimeter (Broman et al., 1987). Further, head perimeter at birth, 1 year, 4 years, and 7 years correlated with IQ scores at age 7 in both Black and White children (r = 0.13 to 0.24).”

On temporal lobes, from the scientist that Rushton cited above:

“The size of the pole of the temporal lobe is less in the Negro than in the white, and less in the Negro female than in the Negro male…The shape of the pole of the temporal lobe is different in the two races, being slightly more slender in the Negro, and almost the same size in the two races antero-posteriorly. The differences are not only absolute but are also relative to the to the weight and size of the entire cerebral hemispheres.”

.”Development in these brain regions appears sensitive to the child’s environment and nurturance. These observations suggest that interventions aimed at improving children’s environments may also alter the link between childhood poverty and deficits in cognition and academic achievement,” the study concludes.

“Appears sensitive”. I doubt it. See the table on test scores and income above.

In a related editorial, Joan L. Luby, M.D., of the Washington University School of Medicine, St. Louis, writes: “Building on a well-established body of behavioral data and a smaller but expanding body of neuroimaging data, Hair et al provide even more powerful evidence of the tangible detrimental effects of growing up in poverty on brain development and related academic outcomes in childhood. … In developmental science and medicine, it is not often that aspects of a public health problem’s etiology and solution become clearly elucidated. It is even less common that feasible and cost-effective solutions to such problems are discovered and within reach. Based on this, scientific literature on the damaging effects of poverty on child brain development and the efficacy of early parenting interventions to support more optimal adaptive outcomes represent a rare roadmap to preserving and supporting our society’s most important legacy, the developing brain. This unassailable body of evidence taken as a whole is now actionable for public policy.”

I’m assuming they have never seen the SAT score gaps and how whites in families making less than 20,000 dollars a year score the same as blacks in families making over 200,000 dollars a year.


It’s well-known that IQ is the best predictor of success in life. Blacks have a lower a lower average IQ, and smaller brains than whites and Asians which explains the achievement test score gaps. I would like to see a study that separates rich blacks, rich whites and poor blacks and poor whites with controls and see how they differ. I’m assuming it’ll be the same as the SAT score gaps which I have linked above.

The difference in brain size between blacks and whites perfectly describe what is being shown above. More blacks live in poverty because they have lower IQ. IQ is correlated with poverty, crime, illegitimacy, and chronic welfare status. G, or general intelligence, is highly correlated with most things in life. Excerpt from THE g FACTOR The Science of Mental Ability by Arthur Jensen:

The well-established correlation of IQ and similar cognitive measures with a number of social variables, such as poverty, crime, illegitimacy, and chronic welfare status, makes it almost a certainty that g itself is the major cognitive component in the relationship. However, I have not found a study that directly addresses the extent to which just g itself, rather than IQ or other highly gloaded measures, is related to social variables. The repeated finding that verbal test scores are somewhat more highly correlated with delinquent and criminal behavior than are nonverbal performance tests (generally loaded on the spatial factor) suggests that other cognitive factors in addition to g are probably responsible for the correlation of IQ with these most common forms of antisocial behavior. pg 294

In conclusion, they need to have studies that have poor whites and poor blacks, rich blacks and rich whites, rich whites and poor blacks, poor whites and rich blacks and controls to see what the differences really are, and we know there will be differences between the above-mentioned groups, and that poor whites still perform better academically than poor blacks.


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Charles Murray

Arthur Jensen

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