The Bell Curve: Intelligence and Class Structure in American Life (45 page)

Despite the forbidding air that envelops the topic, ethnic differences in cognitive ability are neither surprising nor in doubt. Large human populations differ in many ways, both cultural and biological. It is not surprising that they might differ at least slightly in their cognitive characteristics. That they do is confirmed by the data on ethnic differences in cognitive ability from around the world. One message of this chapter is that such differences are real and have consequences. Another is that the facts are not as alarming as many people seem to fear.

East Asians (e.g., Chinese, Japanese), whether in America or in Asia, typically earn higher scores on intelligence and achievement tests than white Americans. The precise size of their advantage is unclear; estimates range from just a few to ten points. A more certain difference between the races is that East Asians have higher nonverbal intelligence than whites while being equal, or perhaps slightly lower, in verbal intelligence.

The difference in test scores between African-Americans and EuropeanAmericans as measured in dozens of reputable studies has converged on approximately a one standard deviation difference for several decades. Translated into centiles, this means that the average white person tests higher than about 84 percent of the population of blacks and that the average black person tests higher than about 16 percent of the population of whites.

The average black and white differ in IQ at every level of socioeconomic status (SES), but they differ more at high levels of SES than at low levels. Attempts to explain the difference in terms of test bias have failed. The tests have approximately equal predictive force for whites and blacks.

In the past few decades, the gap between blacks and whites narrowed by perhaps three IQ points. The narrowing appears to have been mainly caused by a shrinking number of very low scores in the black population rather than
an increasing number of high scores. Improvements in the economic circumstances of blacks, in the quality of the schools they attend, in better public health, and perhaps also diminishing racism may be narrowing the gap.

The debate about whether and how much genes and environment have to do with ethnic differences remains unresolved. The universality of the contrast in nonverbal and verbal skills between East Asians and European whites suggests, without quite proving, genetic roots. Another line of evidence pointing toward a genetic factor in cognitive ethnic differences is that blacks and whites differ most on the tests that are the best measures of g, or general intelligence. On the other hand, the scores on even highly g-loaded tests can be influenced to some extent by changing environmental factors over the course of a decade or less. Beyond that, some social scientists have challenged the premise that intelligence tests have the same meaning for people who live in different cultural settings or whose forebears had very different histories.

Nothing seems more fearsome to many commentators than the possibility that ethnic and race differences have any genetic component at all. This belief is a fundamental error. Even if the differences between races were entirely genetic (which they surely are not), it should make no practical difference in how individuals deal with each other. The real danger is that the elite wisdom on ethnic differences—that such differences cannot exist—will shift to opposite and equally unjustified extremes. Open and informed discussion is the one certain way to protect society from the dangers of one extreme view or the other.

E
thnic differences in measured cognitive ability have been found since intelligence tests were invented. The battle over the meaning of these differences is largely responsible for today’s controversy over intelligence testing itself. That many readers have turned first to this chapter indicates how sensitive the issue has become.

Our primary purpose is to lay out a set of statements, as precise as the state of knowledge permits, about what is currently known about the size, nature, validity, and persistence of ethnic differences on measures of cognitive ability. A secondary purpose is to try to induce clarity in ways of thinking about ethnic differences, for discussions about such differences tend to run away with themselves, blending issues of fact, theory, ethics, and public policy that need to be separated.

The first thing to remember is that the differences among individuals
are far greater than the differences between groups. If all the ethnic differences in intelligence evaporated overnight, most of the intellectual variation in America would endure. The remaining inequality would still strain the political process, because differences in cognitive ability are problematic even in ethnically homogeneous societies. The chapters in Part II, looking only at whites, should have made that clear. But the politics of cognitive inequality get hotter—sometimes too hot to handle—when they are attached to the politics of ethnicity. We believe that the best way to keep the temperature down is to work through the main facts carefully and methodically. This chapter first reviews the evidence bearing on ethnic differences in cognitive ability, then turns to whether the differences originate in genes or in environments. At the chapter’s end, we summarize what this knowledge about ethnic differences means in practical terms.

We frequently use the word
ethnic
rather than
race,
because race is such a difficult concept to employ in the American context.
¹
What does it mean to be “black” in America, in racial terms, when the word black (or African-American) can be used for people whose ancestry is more European than African? How are we to classify a person whose parents hail from Panama but whose ancestry is predominantly African? Is he a Latino? A black? The rule we follow here is to classify people according to the way they classify themselves. The studies of “blacks” or “Latinos” or “Asians” who live in America generally denote people who
say
they are black, Latino, or Asian—no more, no less.

Ethnic Nomenclature

We want to call people whatever they prefer to be called, including their preferences for ethnic labels. As we write, however, there are no hard-and-fast rules. People from Latin America wish to be known according to their national origin: Cuban-American, Mexican-American, Puerto Rican, and so forth.
Hispanic
is still the U.S. government’s official label, but
Latino
has gained favor in recent years. We use Latino. Opting for common usage and simplicity, we usually use
black
instead of
African-American
and
white
(which always refers to non-Latino whites) instead of
European-American
or
Anglo.
Americans of Asian descent are called
Asian
when the context leaves no possibility of confusion with Asians living in Asia. We shift to the hyphenated versions for everyone when it would avoid such confusions or when, for stylistic reasons, the hyphenated versions seem appropriate.

It would be disingenuous to leave the racial issue at that, however, for race is often on people’s minds when they think about IQ. Thus we will eventually comment on cognitive differences among races as they might derive from genetic differences, telling a story that is interesting but still riddled with more questions than answers. This prompts a second point to be understood at the outset: There are differences between races, and they are the rule, not the exception. That assertion may seem controversial to some readers, but it verges on tautology: Races are by definition groups of people who differ in characteristic ways. Intellectual fashion has dictated that all differences must be denied except the absolutely undeniable differences in appearance, but nothing in biology says this should be so. On the contrary, race differences are varied and complex—and they make the human species more adaptable and more interesting.

So much for preliminaries. Answers to commonly asked questions about the ethnic groups in America follow, beginning with the basics and moving into successively more complicated issues. The black-white difference receives by far the most detailed examination because it is the most controversial and has the widest social ramifications. But the most common question we have been asked in recent years has not been about blacks but about Asians, as Americans have watched the spectacular economic success of the Pacific rim nations at a distance and, closer to home, become accustomed to seeing Asian immigrant children collecting top academic honors in America’s schools.

Probably yes, if Asian refers to the Japanese and Chinese (and perhaps also Koreans), whom we will refer to here as East Asians. How much higher is still unclear. Richard Lynn, a leading scholar of racial and ethnic differences, has reviewed the assembled data on overall Asian IQ in two major articles. In his 1991 review of the literature, he put the median IQ for the studies of Chinese living in Hong Kong, Singapore, Taiwan, and China proper at 110; the median IQ for the studies of Japanese living in Japan at 103; and the median for studies of East Asians living in North America at 103.
²
But as Lynn acknowledges, these comparisons
are imprecise because the IQs were not corrected for the changes that have been observed over time in national IQ averages. In Lynn’s 1987 compilation, where such corrections were made, the medians for both Chinese and Japanese were 103.
³
Mean white American IQ is typically estimated as 101 to 102.
⁴
Additional studies of Chinese in Hong Kong, conducted by J. W. C. Chan using the Ravens Standard Progressive Matrices, a nonverbal test that is an especially good measure of g, found IQ equivalents in the region of 110 for both elementary and secondary students, compared to about 100 for whites in Hong Kong.
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Another study postdating Lynn’s review compared representative samples of South Korean and British 9-year-olds and found an IQ difference of nine points.
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The most extensive compilation of East Asian cognitive performance in North America, by Philip Vernon, included no attempt to strike an overall estimate for the current gap between the races, but he did draw conclusions about East Asian-white differences in verbal and nonverbal abilities, which we will describe later in the chapter.
⁷
In addition to studies of abilities, Vernon compiled extensive data on the schoolwork of East Asians, documenting their superior performance by a variety of measures ranging from grades to the acquisition of the Ph.D. Is this superior performance caused by superior IQ? James Flynn has argued that the real explanation for the success of Asian-Americans is that they are overachievers.
⁸
He also says that Asian-Americans actually have the same nonverbal intelligence as whites and a fractionally lower verbal intelligence.
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Richard Lynn disagrees and concludes from the same data used by Flynn that there is an ethnic difference in overall IQ as well.
¹⁰

The NLSY is not much help on this issue. The sample contained only forty-two East Asians (Chinese, Japanese, and Koreans). Their mean IQ was 106, compared to the European-American white mean of 103, consistent with the evidence that East Asians have a higher IQ than whites but based on such a small sample that not much can be made of it.

The indeterminancy of the debate is predictable. The smaller the IQ difference, the more questionable its reality, and this has proved to be the case with the East Asian—white difference. It is difficult enough to find two sets of subjects within a single city who can be compared without problems of interpretation. Can one compare test scores obtained in different years with different tests for students of different agee in different cultural settings, drawn from possibly different socioeconomic
populations? One answer is that it can be done through techniques that take advantage of patterns observed over many studies. Lynn in particular has responded to each new critique, in some cases providing new data, in others refining earlier estimates, and always pointing to the striking similarity of the results despite the disparity of the tests and settings.
¹¹
But given the complexities of crossnational comparisons, the issue must eventually be settled by a sufficient body of data obtained from identical tests administered to populations that are comparable except for race.

We have been able to identify three such efforts. In one, samples of American, British, and Japanese students ages 13 to 15 were administered a test of abstract reasoning and spatial relations. The American and British samples had scores within a point of the standardized mean of 100 on both the abstract and spatial relations components of the test; the Japanese adolescents scored 104.5 on the test for abstract reasoning and 114 on the test for spatial relations—a large difference, amounting to a gap similar to the one found by Vernon for Asians in America.
¹²

In a second set of studies, 9-year-olds in Japan, Hong Kong, and Britain, drawn from comparable socioeconomic populations, were administered the Ravens Standard Progressive Matrices. The children from Hong Kong averaged 113; from Japan, 110; and from Britain, 100—a gap of well over half a standard deviation between both the Japanese and Hong Kong samples and a British one equated for age and socioeconomic status.
¹³

The third set of studies, directed by Harold Stevenson, administered a battery of mental tests to elementary school children in Japan, Taiwan, and Minneapolis, Minnesota. The key difference between this study and the other two was that Stevenson and his colleagues carefully matched the children on socioeconomic and demographic variables.
¹⁴
No significant difference in overall IQ was found, and Stevenson and colleagues concluded that “this study offers no support for the argument that there are differences in the general cognitive functioning of Chinese, Japanese, and American children.”
¹⁵