The Bell Curve: Intelligence and Class Structure in American Life
Page 45
Aside from the issue of school quality is the question of whether simply going to school makes any difference to one’s intelligence. The answer is self-evidently yes. Going to school and learning how to read and write, manipulate numbers, find out about one’s culture and about the discoveries of science are going to raise scores on IQ tests compared to not going to school. But although it is obvious that schooling itself fosters intelligence, it is far less obvious how much of the intellectual variation around us can be attributed to differences in the amount of schooling people get. If large numbers of people were getting no schooling at all, there would be cognitive disadvantages on a grand scale that could be blamed on a lack of formal education. But in modern countries, natural variation does not span so wide a range.
An example of a study that had enough natural variation in it to find an effect of schooling was done in Sweden a half-century ago.25 IQ tests were given in 1938 to a representative sample of several hundred 10-year-old boys in public and private schools in a Swedish city. Ten years later, the boys were tested again as part of an induction examination for national military service. In addition to the two IQ scores, the boys’ home and family backgrounds and the total years of schooling were available for analysis.
The average subject in the study had completed only eight years of schooling, which means that many of them had completed fewer. Fewer than 10 percent of them had finished high school, and still fewer had gone on to university. Compared to present-day Sweden or America, the men experienced a wide range of years in school. Even so, the main determiner by far of IQ at the age of 20 was the IQ at the age of 10, by a factor of more than five times as important as years of schooling.26 On the other hand, schooling was a significant though much weaker predictor, after holding IQ at age 10 and family background constant. Since there was some beneficial effect of schooling, the results of the study were properly used to argue that additional years of school would pay off in higher scores.
We can infer from the Swedish study that some of the Flynn effect around the world is explained by the upward equalization of schooling, but a by-product is that schooling in and of itself no longer predicts adult intelligence as strongly, assuming it did so when many people were not getting much schooling.27 The more uniform a country’s schooling is, the more correlated the adult IQ is with childhood IQ.
The average American now gets more than three extra years of schooling compared to the time when the earliest intelligence tests were given. To be sure, years spent in school still varies in America, and it is presumably still contributing to variation in cognitive abilities.28 But given how small the effect was in the Sweden of the 1930s and 1940s, it is unlikely to be large in America today, given the enormous compression of educational variation in America during the twentieth century (see Chapters 1 and 6). Nevertheless, we accept the basic premise that variation in the amount of schooling accounts for some portion of the observed variation in cognitive ability. Besides not knowing how large this remaining effect is, it is hard to estimate how much more would be gained on the average by further equalization of years of schooling. Gains reaped at the bottom of the cognitive ability distribution may be paid for by losses at the top, a process we discuss in the next chapter.
School differences can nonetheless be important. If a child is near the top of the intelligence distribution to begin with, the school can make a major difference in whether that intellectual talent is actually realized, a topic we consider in the next chapter. Or if a child has specific learning disabilities, access to the latest pedagogical techniques and technology may make a major difference. There doubtless are, in addition, pockets in America’s vast educational realm where schools are uncommonly good or uncommonly poor, in which the children are benefiting or suffering cognitively. By definition, however, these are unusual cases, not likely to show up in national data on intelligence.
This discussion has not meant to imply that the fostering of cognitive ability is the only result we want from schools. The civility, let alone the safety, of the environment may vary widely from school to school. Skillful teachers may make learning more interesting. They may infuse children with a love of learning to some extent. These are effects worth worrying about, but they do not alter the fundamental message that the data convey: Equalizing the amount or objective quality of schooling in America cannot be counted on to equalize cognitive ability much.
Compensatory Education
Just a year prior to the Coleman report, the U.S. Congress passed the Elementary and Secondary Education Act (ESEA) of 1965, thereby opening a massive and continuing effort to improve the education of disadvantaged students that continues to this day. In the first fiscal year, grants for educationally deprived children under Title I of the ESEA went from zero to $3 billion, rose to $4 billion in the next year, and have remained there, or higher, ever since. Expenditures in fiscal 1992 were at an all-time high of $5.6 billion (all figures are in 1990 dollars).29
Sponsors of Title I assumed that these programs would narrow the gap in cognitive functioning between disadvantaged children and other students. To prove this, the act also funded an aggressive, ongoing evaluation effort, resulting over the years in a mounting stack of reports. In the mid-1970s, the National Institute of Education (NIE) commissioned a synthesis of the results. Reviewing all the federal studies from 1965 to 1975, researchers found no evidence that students in compensatory education programs closed the gap with their more able peers. Some plausible data suggested that “students in compensatory programs tend to fall behind other students, but not as fast as if they had received no compensatory instructions,” an outcome that the institute treated as evidence of success.30 The greatest support in the various studies was for a simpler “no effect” conclusion: The gap was about as great after compensatory education as before.31 No evidence whatsoever supported a conclusion that compensatory education narrowed the achievement gap.
More optimistically, supporters of compensatory education can call upon the evidence of converging black-white test scores that we described in Chapter 13 as indirect evidence that something positive has been happening in elementary and secondary education for minorities. As we described, improvement has been the largest at the bottom of the IQ distribution, which in turn points toward compensatory programs as a possible cause. But direct evidence of the link remains elusive. In recent years, compensatory programs have set more modest goals, for themselves.32 Now, they focus on teaching specific academic skills or problem solving, not expecting improvements in overall academic achievement or general intelligence.33
Stories Too Good to Be True
Accounts of phenomenal success stories in education—the inner-city school that suddenly excels as the result of a new program or a new teacher—are a perennial fixture of American journalism. Are they true? If the question is whether an inspirational teacher or some new program has the capacity to make an important difference in students’ lives, then the answer is surely yes. But claims for long-term academic improvement, let alone increases in cognitive functioning, typically fade as soon as hard questions begin to be asked. A case in point is Chicago’s Marva Collins, who gained national attention with claims that her shoestring-budget inner-city school, launched in 1975, was turning out students who blew the top off standardized tests and were heading to the best universities. Between the ages of 5 and 10, she claimed, her pupils, deemed “unteachable” in regular schools, were reading Plato, Aristotle, Chaucer, Shakespeare, and Tolstoy, according to stories in the popular media. According to other newspaper reports, she was asked by both Presidents Reagan and Clinton to become secretary of education. She continues to train large numbers of teachers in her methods.34 Are her celebrated anecdotes borne out by data? We do not know. Despite years of publicity about Marva Collins, we can find no hard evidence.35
More generally, the large test score increases in local schools that are widely and routinely reported by the media have been plagued by fraud. In several schools in
and around Washington, D.C., for example, the Washington Post reported that gains in test performance were found to be due to improper coaching on the tests by school employees or by allowing extra time for students to complete the tests.36 A story in the Los Angeles Times told of various methods of cheating on standardized tests, including the replacing of wrong answers with right ones by teachers and staff, in at least fifty elementary public schools statewide.37 The New York Times wrote about a public school principal who had been caught tampering with student test scores for years.38 These specific instances seem to be part of a widespread problem.39
Raising IQ Among the School-Aged: Converging Results from Two Divergent Tries
The question remains: Is there any evidence that cognitive ability as measured by IQ tests can be increased by special interventions after children reach school age? We have some reason for thinking the answer is a highly qualified yes, and some basis for estimating how much, from two sources of evidence drawn from strikingly different contexts.
The first is one of the largest controlled experiments attempting explicitly to raise the intelligence of school-age children. It occurred in Venezuela, where in 1979 the incoming president named to his cabinet a Minister of State for the Development of Human Intelligence.40 The new minister was convinced that a nation’s average intellectual level was fundamental to its well-being, and he set out to see what could be done to raise the IQ of Venezuelan school children. The result was Project Intelligence, designed over four years by a team of Venezuelan and American psychologists, educators, and other specialists. In the fifth year, 900 youngsters in seventh grade in a poor district of a Venezuelan provincial city were randomly divided into experimental and control groups.41 Those in the experimental group were taught approximately sixty forty-five-minute lessons in addition to their regular curriculum during the year and were cognitively tested before, during, and after the year. The students in the control group were tested at the same intervals, without receiving any of the additional instruction. The special lessons involved instruction in the kinds of intellectual activities that turn up on intelligence tests—visuospatial and verbal reasoning, vocabulary and word analogies—in addition to lessons in inventive thinking.42 At the end of the year, the youngsters in the experimental group, compared to the controls, had gained a net of more than 0.4 standard deviation on a conventional intelligence test and a net gain of just over 0.1 standard deviation on a culture-fair intelligence test—in other words, a net gain in the range between 1.6 and 6.5 IQ points. There was no chance to see if the gain faded out or was reflected in the rest of the students’ academic performance, nor can we even guess how much a second or third year of lessons would have accomplished.
The second source of evidence comes from the unsystematic but massive attempt to raise intelligence that goes on in the innumerable commercial coaching services promising to raise SAT scores. Few people think of the prep courses in that way. On the surface, it is all about getting into the college of your choice. But raising an SAT is just like raising an IQ if the SAT is an intelligence test and, however adroitly the current officials of the College Board and the admissions officers in universities try to avoid saying so, the SAT is partly an intelligence test.43
Can the SAT be coached? Yes, but it is not easy. Everyone who looks into this topic immediately hears about students who gained 100, 150, or 200 points on the SAT after a few hours of coaching. The tales may even be true, but they need to be averaged with the tales that don’t get told about the scores that improve by only a few points—and the scores that drop—after spending a few dozen hours and hundreds of dollars on a coaching course. Scholars have by now largely sorted out the reality behind the sales pitches. After a furious debate about the issue in the late 1970s and early 1980s, the best evidence indicates that the coaching programs which can offer convincing scientific backing for their claims consist not of a few hours of practice but of lengthy training, comparable to going to school full time.44 In the best of these analyses, Samuel Messick and Ann Jungeblut reviewed the published studies on coaching for the SAT, eliminated the ones that were methodologically unsound, and estimated in a regression analysis the point gain for a given number of hours spent studying for the test.45 Their estimate of the effect of spending thirty hours on either the verbal or math test in a coaching course (including homework) was an average of sixteen points on the verbal SAT and twenty-five points for the math SAT Larger investments in time earn larger payoffs with diminishing returns. For example, 100 hours of studying for either test earns an average twenty-four points on the verbal SAT and thirty-nine points on the math SAT The next figure summarizes the results of their analysis.
Studying really does help, but consider what is involved. Sixty hours of work is not a trivial investment of time, but it buys (on average) only forty-one points on the combined Verbal and Math SATs—typically not enough to make much difference if a student is trying to impress an admissions committee. Even 300 hours—and now we are talking about two additional hours for 150 school days—can be expected to reap only seventy additional points on the combined score. And at 300 hours (150 for each test), the student is already at the flat part of the curve. Double the investment to 600 hours, and the expected gain is only fifteen more points.
The diminishing returns to coaching for the SAT
Source: Messick and Jungeblut 1981, Figs. 1, 3.
Although intended for utterly different purposes, the benefits of the Venezuelan program and of SAT coaching schools are remarkably similar. The sixty lessons of the Venezuelan course, representing forty-five hours of study, added between .1 and .4 standard deviation on various intelligence tests. From the figure on SAT coaching, we estimate that 45 hours of studying adds about .16 standard deviation to the Verbal score and about .23 standard deviation to the Math score.46
These increases in test scores represent a mix of coaching effects—“cramming” is the process, with a quite temporary effect, that you may remember from school days—and perhaps an authentic increase in intelligence. We also are looking at short-term results here and must keep in mind that whenever test score follow-ups have been available (see the next section), the gains fade out. The net result is that any plausible estimate of the long-term increase in real cognitive ability must be small, and it is possible to make the case that it approaches zero.
Taken together, the negative findings about the effects of natural variation in schools, the findings of no effect except maybe to slow the falling-behind process in the evaluations of compensatory education, and the results of the Venezuelan and SAT coaching efforts all point to the same conclusion: As of now, the goal of raising intelligence among school-age children more than modestly, and doing so consistently and affordably, remains out of reach.
HEAD START AND ITS SOMETIMES DISTANT RELATIVES
During the 1970s when scholars were getting used to the disappointing results of programs for school-age children, they were also coming to a consensus that IQ becomes hard to budge at about the time children go to school. Longitudinal studies found that individual differences in IQ stabilized at approximately age 6.47 Meanwhile, developmental psychologists found that the year-to-year correlations in mental test performance were close to zero in the first few years of life and then rose to asymptotic levels by age 6.48 These findings conformed with the intuitive notion that, in the poet’s words, “as the twig is bent the tree’s inclined.” 49 Any intervention designed to increase intelligence (or change any other basic characteristics of the child) must start early, and the earlier the better.50 Here, we will characterize the more notable attempts to help children through preschool interventions and summarize the expert consensus about them.
Preschool Programs for Disadvantaged Children in General
HEAD START. One of the oldest, largest, and most enduring of the contemporary programs designed to foster intellectual development came about as the result of the Economic Opportunity Act of 1964, the opening salvo of Lyndon Johns
on’s War on Poverty. A year later, the mandated executive agency, the Office of Economic Opportunity, launched Project Head Start, a program intended to break the cycle of poverty by targeting preschool children in poor families.51 Designed initially as a summer program, it was quickly converted into a year-long program providing classes for raising preschoolers’ intelligence and communication skills, giving their families medical, dental, and psychological services, encouraging parental involvement and training, and enriching the children’s diets.52 Very soon, thousands of Head Start centers employing tens of thousands of workers were annually spending hundreds of millions of dollars at first, then billions, on hundreds of thousands of children and their families.
The earliest returns on Head Start were exhilarating. A few months spent by preschoolers in the first summer program seemed to be producing incredible IQ gains—as much as ten points.53 The head of the Office of Economic Opportunity54 reported the gains to Congress in the spring of 1966, and the program was expanded. By then, however, experts were noticing the dreaded “fade-out,” the gradual convergence in test scores of the children who participated in the program with comparable children who had not. To shorten a long story, every serious attempt to assess the impact of Head Start on intelligence has found fade-out.55 Cognitive benefits that can often be picked up in the first grade of school are usually gone by the third grade. By sixth grade, they have vanished entirely in aggregate statistics.
Head Start programs, administered locally, vary greatly in quality. Perhaps, some have suggested, the good programs are raising intelligence, but their impact is diluted to invisibility in national statistics.56 That remains possible, but it becomes ever less probable as time passes without any clear evidence for it emerging. To this point, no lasting improvements in intelligence have ever been statistically validated with any Head Start program. Many of the commentators who praise Head Start value its family counseling and public health benefits, while granting that it does not raise the intelligence of the children.57