Fact: Social intervention has been shown to raise IQ at every year of childhood.
Summary
Social intervention has been proven to raise IQs at every age level of childhood: infancy, preschool, elementary and middle school. The problem is that these programs are not sustained, so the gains fade as quickly as they are made. The Bell Curve argues that this proves that social intervention is ineffective, and therefore not worth it. But adoption studies show that when enriched environments are sustained through adolescence (the critical cut-off point), the IQ gains become permanent.
Argument
Although the authors of The Bell Curve estimate that intelligence is 40 percent environmental, they are quite pessimistic that social intervention can raise IQs. Herrnstein and Murray write: "Taken together, the story of attempts to raise intelligence is one of high hopes, flamboyant claims, and disappointing results. For the foreseeable future, the problems of low cognitive ability are not going to be solved by outside intervention to make children smarter." (1) They go on to argue that because there is little hope of raising the IQs of minorities, attempts to make them equal are a waste of the taxpayers' money. On this basis they recommend the abolishment of welfare and affirmative action. Murray argues, "For many people, there is nothing they can learn that will repay the cost of teaching." (2)
But it is simply untrue that the history of social intervention to raise IQ has been a failure. Social intervention has been proven to raise IQs at every age of development, from birth to high school (and possibly even beyond). Before reviewing the studies for each age group, however, it is useful to know the three main schools of thought on IQ (and child) development.
The first school, Herrnstein and Murray's, holds that IQ is largely genetic (60 percent, by their estimate). It is therefore surprisingly stable and impervious to social intervention. They believe that IQ at age four is a good predictor of IQ at age 18.
The second is the "ballistic" or "critical-period" school, which holds that a child's first five years are the critical developmental years. Although both genes and the environment contribute to a child's traits, social intervention must be done before age five, because afterwards change becomes exponentially more difficult.
The third is the "through adolescence" school, which is basically the ballistic school extended over a much longer period of time. Until children reach their teenage years, their traits are more malleable and susceptible to social intervention. A bad start in life is not necessarily detrimental if corrected before adolescence; conversely, early gains may be wiped out by deteriorating circumstances later on. By one's teenage years, though, personal traits begin hardening into more permanent ones (although this process may never be complete).
Just one example is learning a foreign language. To speak absolutely fluently -- without even the slightest trace of an accent -- a person has to learn a foreign language before the age of 13. "After that age," says Judith Aissen, a linguist from the University of California, "something solidifies or hardens in the brain. No matter how smart you are, no matter how hard you try, you will almost always learn a language with an accent after this age." (3) The converse is also true: if a child immigrates from Russia to America at the age of six, and is completely immersed in American culture with little opportunity to speak his native language, he will eventually lose his command of Russian -- not just in vocabulary, but in grammar and accent as well. Some think that "it's like riding a bike," that if the adult returned to Russia, it would all come back. But, surprisingly enough, that is not true. The ability fell into disuse before adolescence, and he will speak Russian as if it were a learned foreign language.
Which of the above three paradigms is correct? A review of the research literature below shows that only the third is compatible with the evidence. It is interesting to note, however, that Herrnstein and Murray seem genuinely unaware of this third school of thought; they don't even consider it in their writing, let alone argue against it. All their arguments are against the ballistic model. If a social program is tried for a year or two, and the IQ gains of the children are lost over the next few years, they treat this as proof that social intervention doesn't work. It doesn't occur to them that the program should be continued through adolescence. This characterizes every single argument they make against a social program that doesn't work. What this means is really rather remarkable -- the entire argument against social intervention in The Bell Curve is completely nonresponsive to the positions of most environmentalists.
Infant intervention
There are at least a dozen major studies which show that intervention can raise IQs in infants (from birth to age three). (4) The best of these was a very large, eight-site study published in Pediatrics in 1992, which found that intervention for at-risk infants (those born prematurely or with low birth weights) raised their IQs nine points by age three. (5)
Curiously, Herrnstein and Murray mention none of this vast literature in The Bell Curve. Instead, they only describe two other studies -- The Abecedarian Project and the Milwaukee Project -- which suffer from statistical or design flaws, even though they produced encouraging results like the studies above. Psychologists have heavily criticized the authors of The Bell Curve for this negative, one-sided review of the evidence.
Preschool intervention
Head Start is perhaps the best known social intervention for children aged three to five. It is a truly comprehensive program, covering six areas: early childhood education, health screening and referral, mental health services, nutrition education and hot meals, social services for the children and their families, and parent involvement. Head Start produces dramatic results while it remains in effect: it can immediately boost a child's IQ the equivalent of about eight points. (6)
Unfortunately, the gains associated with Head Start begin to fade out once the program is stopped, which is usually when the child enters school. By the end of the third grade, almost all the IQ gains have vanished. (7) Herrnstein and Murray argue that this proves that IQ cannot be permanently raised, and suggest the reason why is because IQ is largely genetic. But the obvious rejoinder is that the gains could be maintained if the program were maintained. Again, the authors seem to be stuck in a false dichotomy, one between the genetic and the ballistic model. The fade-out effect of Head Start does not eliminate the possibility that a child's developmental years extend through adolescence -- hence Herrnstein and Murray cannot automatically claim the victory for genetics.
Primary and middle school intervention
What happens when the enrichment of Head Start is continued into a child's early school years? Studies show that, in the few cases where this has happened, the intellectual gains are largely sustained. (8) Even Herrnstein and Murray give an example of a successful intervention -- one that was introduced not during preschool, like Head Start, but during middle school. In 1979, the Venezuelan government began Project Intelligence, an experiment in which 900 seventh-graders from a poor district were divided into two groups. The experimental group was given sixty extra 45-minute lessons during their school year, which resulted in a gain of 1.6 to 6.5 IQ points over the control group. (9) These are large gains for such a modest program, yet Herrnstein and Murray dismiss them. Why? Because the program was continued for only one year, and no one knows if further effort would have produced further gains, or even if the gains faded away. But the fact that social intervention produces IQ gains even in the 7th grade strongly suggests that Head Start is terminated too quickly in the U.S.
A University of Michigan study shows the IQ gains by Head Start are in fact undermined by the poor elementary schools that Head Start recipients enter. The researchers analyzed data on 14,800 eighth-graders, some of whom were former Head Start recipients, some recipients of other forms of preschool, and others none at all. They found that those who have received Head Start (typically the nation's poorest) attend schools that rank among the academically weakest and most problem-ridden in the nation, even after correcting for race and other demographic variables. (10) Obviously, if personal development continues through adolescence, then exposure to eight years of crime, drugs and a weak curriculum before then is going to depress it. A tireless crusader for improving disadvantaged schools is William Bennett, Reagan's former Secretary of Education. Bennett has compiled an impressive list of interventions that work, from elementary to high school. (11) Again, The Bell Curve does not even mention these successful programs.
The problem with many intervention programs is that they are simply too limited to counteract the pervasive effects of poverty. A few years of Head Start are not going to negate 13 years of ubiquitous poverty. Poverty results in the worst of everything: worse nutrition, worse health care, worse education, worse living environments, worse jobs, worse social problems… Giving a child a few extra lessons a week is little more than putting a band-aid on the whole problem. What a child really needs is to be lifted completely out of poverty.
How can we test this hypothesis? Scientists know of two ways in particular: nutrition and adoption studies.
Nutrition and IQ
Changes of nutrition for an entire geographical region offer excellent evidence for the environmental causes of IQ. Nutrition has been improving around the world as science and technology resolve problems of scarcity and reduce the level of absolute poverty almost everywhere. And this has coincided with the "Flynn Effect," which is the rise of average IQs around the world by three points per decade. Better nutrition has resulted in taller, stronger, larger and faster humans around the world; there is no reason to believe that it wouldn't make them smarter as well.
Narrower experiments with nutrition verify this observation. In a study of 60 Welsh children (aged 12 to 13), researchers gave half of them a substantial vitamin supplement and half of them placebos for eight months. The experimental group gained 8 points on their nonverbal test scores over the control group. (12) A similar 13-week experiment with 600 California 8th and 10th-graders resulted in a four point gain in nonverbal test scores. (13) In both studies, verbal scores were not affected, but that is consistent with the Flynn Effect, which is seeing nonverbal, rather than verbal, scores rising.
Herrnstein and Murray hedge on these findings, because other studies have not duplicated these results, and scientists don't know the exact role nutrition plays in IQ. True, but they don't know the exact role it plays in height, either, and it's well-known that better nutrition makes for taller people. (After Japan adopted a high-protein Western diet after World War II, the height of their youth shot up in a few generations.) It would be more extraordinary to believe that better nutrition does not improve IQ, rather than it does.
Adoption and IQ
One of the best ways to determine how poverty affects IQ is to study at-risk children who have been adopted by middle or upper-class parents. By changing the entire environment to a healthier one, it is possible to assess the degree to which IQ is environmental. Unfortunately, for many ethical and practical reasons, adoption data are hard to come by.
To date, the Minnesota adoption study is the only one that has been done on black children raised in white homes. Unfortunately, it is beset with statistical and methodological problems, and even the study's authors admit that it is not informative on the question of environment and IQ. (14) Just one of the many problems is evaluating school attendance for a black child from a white family. If they attend black schools, then that counteracts the study's desire to see how children develop away from poverty-stricken environments. But if they attend white schools, there are problems of prejudice and social stigma. Both could lower IQ.
Outside the U.S., however, there have been successful adoption studies (albeit with small study samples), which have the added benefit of not complicating the issue with race. Michel Schiff and his colleagues studied 32 French children who were born to unskilled, working-class parents and were adopted by upper-class homes. During childhood, their IQs averaged 107 points, which was 12 points higher than their full or half-siblings who were raised for a time by their biological parents or grandparents in lower class surroundings. (15)
Another French study compared four groups of adopted children. These were the children of lower or upper class biological parents who had been adopted by lower or upper class homes. Here are the average IQs of each group:
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