Posts Tagged ‘environment’

By chance, I spotted Richard E. Nisbett’s book Intelligence and How to Get It in the bookstore, glanced through the table of contents, and saw chapter 6: “IQ in Black and White.” An incident in one of the classes I taught prompted me to buy it.

(Note: In this post, I use Nisbett’s convention of “black” to mean Americans of African descent.)


The class incident

I am lecturing about brain structure. A Caucasian student raises their hand and pops out a nonsequitur question.

“Are some races smarter than others?”

“Absolutely not. That’s a myth.”

“No, really. I heard that, you know, some races have better developed brains than others, and they’re smarter.”

Several non-Caucasian faces in the class tighten. Alarm bells go off in my head. I respond from my gut, speaking without proof in a science classroom.

“Well, intelligence comes from cellular processes in the brain. There are variations in brain development in the population, but not by race. It has more to do with the opportunities you have for education in childhood and on how much you use your brain.”

I strongly believe that skin color has no bearing on a person’s intelligence (we all need smarts to survive) and that measured differences have more to do with social situations than biology – particularly after getting a taste of how racism can affect the psyche. But this is science. If the student chose to challenge me again, I would need data to back up my assertions, and I didn’t have it.

Students can find plenty of information online supporting a race-IQ connection. Possibly my student was citing something dissected from The Bell Curve. Indeed, Nisbett notes that

[f]or decades, whites scored an average of 100 points on IQ tests, while blacks scored about 85—a difference of 15 points or a full standard deviation. (pp. 93-94)

What could I use to refute this correlation between race and IQ scores?

Is the race-IQ connection even a valid question to study?

An opinion piece in the journal Nature, which debates the validity and utility of researching the correlation between race and intelligence, highlights a few of the problems inherent in the question.

Steven Rose argues that both “race” and “intelligence” are socially-defined concepts that can’t be put into a scientific, measurable context, and so such studies should not be undertaken.

In a society in which racism and sexism were absent, the questions of whether whites or men are more or less intelligent than blacks or women would not merely be meaningless—they would not even be asked. The problem is not that knowledge of such group intelligence differences is too dangerous, but rather that there is no valid knowledge to be found in this area at all. It’s just ideology masquerading as science.

Stephen Ceci and Wendy M. Williams argue that, while they “think racial and gender differences in IQ are not innate but instead reflect environmental challenges,” race-intelligence research must be encouraged, even when it produces politically incorrect results, in order to spur research to disprove it.

Claims that sex- or race-based IQ gaps are partly genetic can offend entire groups, who feel that such work feeds hatred and discrimination. But hatred and discrimination do not result from allowing scientists to publish their findings, nor does censuring it stamp out hatred. Pernicious folk-theories of racial and gender inferiority predated scientific studies claiming genetic bases of racial differences in intelligence.

While the race-IQ connection may not be a valid line of inquiry, nonetheless, the question has arisen in my science classroom. I feel the need to briefly define intelligence, per Nisbett’s book, and then work through a few bits of evidence he cites to refute a genetic connection among race, genes, and intelligence.

What the heck is intelligence?

Nisbett describes “intelligence” in the first chapter of his book. Per Linda Gottfredson:

[intelligence] involves the ability to reason, plan, solve problems, think abstractly, comprehend complex ideas, learn quickly, and learn from experience. It is not merely book learning, a narrow academic skill, or test-taking smarts. Rather it reflects a broader and deeper capability for comprehending our surroundings—“catching on,” “making sense” of things, or “figuring out” what to do. (p. 4)


IQ is often used as a proxy for intelligence, but the IQ test was specifically designed to predict school achievement, and does not necessarily predict how well an individual will function in society. The IQ test leaves out some types of intelligence, such as pragmatism and empathy, that are highly valued in some cultures (and by many employers).

G factor

Another measure of intelligence, which correlates well with IQ, is the “general intelligence factor” (g factor). The g factor is composed of two parts: crystallized intelligence and fluid intelligence. Crystallized intelligence is the sum of all the facts and patterns a person has learned about the world. The more stimulating a person’s environment (such as in homes where parents use large vocabularies and expose their children to as many educational opportunities as possible), the higher their crystallized intelligence is likely to be. Fluid intelligence involves the ability to solve new, abstract problems. Fluid intelligence is linked to the prefrontal cortex area of the brain—an area that is linked to the limbic system and does not function well when a person is emotionally stressed (such as when confronted by prejudice and poverty).


In addition to traditional intelligence, motivation must be factored into any discussion of success in school or at work. A very intelligent person will not perform well if they are not motivated; a less bright person can perform very well if they have a strong drive to succeed. Peer pressure that discourages kids from “acting smart” can hinder their success. Additionally, prejudice makes it harder for educated minorities (particularly black males) to get jobs, which effectively devalues their diplomas and “[saps] their motivation to complete their education.” (p. 103)

Ammunition to refute the race-IQ correlation

In Intelligence and How to Get It, Nisbett discusses evidence supporting and refuting various hypotheses about the source of intelligence, and concludes that “intelligence is highly modifiable by the environment”—particularly by environmental influences such as education systems and cultural expectations. Further, he argues that the measured racial difference in IQ in the United States is caused by environmental factors, not innate capacity. He refutes genetic race-intelligence difference hypotheses in an appendix. I now have arguments and data to cite if this issue arises in class again. (I could just hug the man!)

I couldn’t possibly describe in a single blog posting all the nuances that refute the race-intelligence relationship. Instead, I highlight a few of the points I found interesting. I have left out tons of good information, so if you’re interested in this topic, I recommend reading the book!

Refuted hypothesis #1a: IQ is due more to inheritance than environment.

Studies showing insignificant difference in intelligence between identical twins adopted into different families cannot be used to argue that environment has negligible influence on intelligence. High socioeconomic status (SES) families give kids the opportunity to develop their intelligence to the fullest, while low SES families are highly variable in that regard.  (Think of the genetic potential for height, which correlates well with inheritance when nutrition is good, but not so well if kids eat poorly.) Adoptive families all tend to be of higher socioeconomic status; therefore, their environments are virtually identical, and the study is fatally flawed. Nisbett aptly references Tolstoy’s Anna Karenina: “Happy families are all alike; every unhappy family is unhappy in its own way.” (See chapter 2 “Heritability and Mutability”.)

The IQ and achievement gap between black and white Americans has decreased over the last several decades—a time period in which

[t]hings have improved both materially and socially for blacks, what with the civil rights movement, affirmative action, the increase in the proportion of blacks who are middle class, and the fact that blacks have penetrated into the highest levels of society . . .”. (p. 232)

In sum, an improved environment (not a genetic change) has resulted in improved test scores.

Refuted hypothesis #1b: The environments of black and white Americans are not sufficiently different to explain the difference in IQ scores.

Blacks tend to be of lower SES than whites, and lower SES is correlated with lower IQ (upper-middle vs. lower SES gives a 12-to-18-point IQ difference, p. 21-22). Lower SES affects intelligence in a variety of ways, including parenting practices and:

poor prenatal care and nutrition, relative infrequency of breast-feeding, hunger, deficiency of vitamins and minerals, lead poisoning, fetal alcohol poisoning, poorer health care, greater exposure to asthma-causing pollution, emotional trauma, poor schools, poor neighborhoods along with the less desirable peers who come with the territory, and much moving and consequent disruption of education. (p. 101)

Even when blacks and whites are of similar incomes (33% gap in 2002), their wealth remains different (88% gap in 2002) and affects their ability to weather economic downturns. In part, this wealth difference is due to historical discrimination in homebuying, which prevented black families from accumulating wealth through real estate. The rate of unmarried mothers is higher in the black community (72%, versus 24% for whites), and a one-adult household can be less stimulating. (See p. 101.)

Social discrimination against blacks exists in the U.S., which results in a lack of “effort optimism.” (p. 104) (What’s the point of working to get ahead when the system will just keep me down?) The psychological effect of this discrimination is powerful—black students do worse on IQ and achievement tests when “in an integrated setting and it is made explicit that it is intellectual ability that is being tested.” (p. 95)

Refuted hypothesis #2: the IQ test is culture-neutral.

IQ tests must be re-normed over succeeding generations because scores keep going up. People’s intelligence can’t go up that fast due to genetics, so the difference must be due to cultural factors. (See chapter 3 “Getting Smarter”.)

As little as three months of a Western-style education improved the ability of African teenagers to perform a variety of spatial perception tasks . . . by as much as .70 standard deviation”. (p. 43)

Refuted hypothesis #3: Sub-Saharan Africans average an IQ of 70; the greater average 85 IQ of African-Americans must be due to European ancestry.

The smartest black children in Chicago’s schools do not have more European ancestry than the rest of the black population, and “blood group assays show no association between degree of European heritage and IQ.” (p. 97)

Refuted hypothesis #6: Brain size is correlated with IQ, blacks have smaller brains than whites, so whites are smarter.

While the evidence supporting the first two parts of this hypothesis are shaky, two quotes can knock this one down:

[T]he brain-size difference between men and women is substantially greater than that between blacks and whites . . ., yet men and women score the same, on average, on IQ tests. (p. 96)

[T]he cranial capacity of black females was the same as that of whites, yet the IQ difference was the usual standard deviation . . . . The IQ difference therefore is found in the absence of a cranial-capacity difference.” (p. 220)

Copyright 2009 by Katie Bradshaw

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