The Bell Curve: Intelligence and Class Structure in American Life (27 page)

In predicting which white youths will never complete a high school education, IQ is more important than SES

Note: For computing the plot, age and either SES (for the black curve) or IQ (for the gray curve) were set at their mean values.

The permanent dropout instead fits the older image, more common among the general public than intellectuals, of the youngster who is both not very smart and from the wrong side of the tracks. To put it technically, the effects of socioeconomic status and intelligence interact. A white youth who had
both
low cognitive ability and a poor socioeconomic background was at even more risk of dropout than the separate effects of each variable would lead one to expect.
¹⁹
Of white youths who were in the bottom quartile on both IQ and socioeconomic status, half permanently dropped out of school.

The “temporary dropouts,” who go back to get a GED, tell a different story. In the figure below, they are compared with students who received a high school diploma in the usual way. In effect, the figure says that if you want to predict who will stay in high school through the diploma, and who will instead drop out of school and eventually get a GED, you are better off sizing up their parents than looking at their IQ scores. In speculating about what lies behind these numbers, three images come to mind. First, there are middle-and the upper-class parents who find it unthinkable that their children should drop out of high school—call the therapist, find a special school, do anything, but keep the child in school. Then one thinks of working-class parents (most of whom are somewhere around the mean on the socioeconomic index), urging their children to get an education and do better than their parents. Finally, one thinks of lower-class parents, the Pap Finns of American folklore, complaining about their children wasting all that time on book learning. The NLSY data are consistent with these popular images. For youths with a socioeconomic background anywhere near or above the mean, the high school diploma is the norm. As socioeconomic background falls below the mean, the probability that the high school certification came through a GED instead of the normal route soars.

For temporary dropouts, the importance of SES increases sharply

Note: For computing the plot, age and either SES (for the black curve) or IQ (for the gray curve) were set at their mean values.

This view also fits into the Cameron and Heckman finding that GED students are more like dropouts than high school graduates in the problems they experience in the labor market. Interpretively, the brighter dropouts may go back to get a GED, but they continue to share in common with the permanent dropouts a lower-class social background that has not inculcated a work ethic that makes for success in the labor force.
²⁰
Thus, GEDs are more like normal graduates in their intelligence but more like other dropouts in their success in the labor force.

All of this interpretation is speculative, and we will leave it to others to determine whether these possibilities stand up to examination. Meanwhile, the results emphasize the need for more open exploration of a topic that has been almost as taboo in some circles as IQ: the possibility that “lower class” in its old-fashioned sense has an impact on how people behave.

One concrete result of this analysis bears on the presentation in this book. The differences between GED graduates and those with regular diplomas are too great to justify grouping them together. Whenever we refer to “a high school education” throughout the rest of Part II, we are referring specifically to the normal high school career, completed by a diploma. GED graduates are excluded.

As a general statement, the relationship of IQ to educational attainment seems to have been remarkably stable. Twenty years ago, one of the leading texts on the Wechsler Adult Intelligence Scale reported that the mean of high school graduates was about 105, the mean of college
graduates was 115, and the mean of people getting medical degrees and Ph.D.s was about 125.
²¹
The book, published in 1972, was based on clinical experience in the 1950s and 1960s. This summary is virtually identical to the story told by the NLSY for whites (who correspond most closely with the college population in the 1950s and early 1960s). The mean IQ of high school graduates was 106, the mean of college graduates was 116, and the mean of people with professional degrees was 126. The relative roles of socioeconomic status and IQ in getting a bachelor’s degree for youths of the late 1970s and 1980s are shown in the figure below.

Two broad implications of these results stand out. The first is suggested by the way that both curves hug the bottom throughout the lefthand side of the graph. The combination of average-or-below parental SES or average-or-below IQ meant that the odds of getting a college degree
are minuscule. The second broad implication is that parental SES is important but not decisive. In terms of this figure, a student with very well-placed parents, in the top 2 percent of the socioeconomic scale, had only a 40 percent chance of getting a college degree if he had only average intelligence. A student with parents of only average SES—lower middle class, probably without college degrees themselves—who is himself in the top 2 percent of IQ had more than a 75 percent chance of getting a degree.

Once again, the common stereotype of the talented-but-disadvantaged-youth-denied-educational-opportunity does not seem to exist in significant numbers any longer. Only seven-tenths of 1 percent of whites in the NLSY were both “prime college material” (IQs of 115 or above) and markedly disadvantaged in their socioeconomic background (in the bottom quartile on the SES index). Among this tiny group, it is true that fewer than half (46 percent) got college degrees. Those who did not, despite having high IQs, may be seen as youths who suffered from having a disadvantaged background. But recall that this group consists of only four-tenths of 1 percent of all white youths. A category of worthy white young persons denied a college education because of circumstances surely exists to some degree, but of such small size that it does not constitute a public policy problem.

What about another stereotype, the untalented child of rich parents who gets shepherded through to a degree? Almost 5 percent of white youths had below-average IQs (under 100) and parents in the top quartile of socioeconomic status. Of those, only 12 percent had gotten college degrees, representing just six-tenths of 1 percent of white youths. Judging from these data, the common assertion that privileged white parents can make sure their children do well in school, no matter what, may be exaggerated.

The act of leaving high school before graduating is a rare event among white youths, conspicuously concentrated in the lowest quartile of cognitive ability. Among those who drop out, both socioeconomic status and cognitive ability are involved. Most dropouts with above-average intelligence go back to get a GED.
²²
But socioeconomic status remains
bound up with the dropout process. The children of lower-class families are more likely to end up with a GED than are the children of average or upper-class families» There is irony in this: Throughout Part II, we describe social problems that are more understandable once cognitive ability is brought into the picture and for which socioeconomic background is not as important as most people think. But the one social problem that has a widely acknowledged cause in cognitive ability—school dropout—also has a strong and complex socioeconomic link.

When it comes to explaining who gets a college education among whites, both academic merit and socioeconomic background play important roles. But while socioeconomic privilege can help if the youngster is reasonably bright, there are limits to what it can do if he is not. And if cognitive ability is high, socioeconomic disadvantage is no longer a significant barrier to getting a college degree.

Economists distinguish between being unemployed and being out of the labor force. The unemployed are looking for work unsuccessfully. Those out of the labor force are not looking, at least for the time being. Among young white men in their late 20s and early 30s, both unemployment and being out of the labor force are strongly predicted by low cognitive ability, even after taking other factors into account.

Many of the white males in the NLSY who were out of the labor force had the obvious excuse: They were still in college or graduate school. Of those not in school, 15 percent spent at least a month out of the labor force in 1989. The proportion was more than twice as high in cognitive Class V as in Class I. Socioeconomic background was not the explanation. After the effects of IQ were taken into account, the probability of spending time out of the labor force went up, not down, as parental SES rose.

Why are young men out of the labor force? One obvious possibility is physical disability. Yet here too cognitive ability is a strong predictor: Of the men who described themselves as being too disabled to work, more than nine out of ten were in the bottom quarter of the IQ distribution; fewer than one in twenty were in the top quarter. A man’s IQ predicted whether he described himself as disabled better than the kinds of job he had held. We do not know why intelligence and physical problems are so closely related, but one possibility is that less intelligent people are more accident prone.

The results are similar for unemployment. Among young white men who were in the labor market, the likelihood of unemployment for high school graduates and college graduates was equally dependent on cognitive ability. Socioeconomic background was irrelevant once intelligence was taken into account.

Most men, whatever their intelligence, are working steadily. However, for that minority of men who are either out of the labor force or unemployed, the
primary risk factor seems to be neither socioeconomic background nor education but low cognitive ability.

H
aving a high IQ makes it easier to do well in a job; we followed that story in Chapter 3. But what about the relationship of cognitive ability to that crucially important social behavior known as “being able to get and hold a job.” To what extent are dropouts from the labor force concentrated in the low-IQ classes? To what extent are the unemployed concentrated there?

In the following discussion, we limit the analysis to males. It is still accepted that women enter and leave the labor force for reasons having to do with home and family, introducing a large and complex set of issues, whereas healthy adult men are still expected to work. And yet something troubling has been happening in that area, and for a long time. The problem is shown in the figure below for a group of young men who are likely to be (on average) in the lower half of the IQ distribution: men 16 to 19 years who are not enrolled in school.