Myth: Social intervention cannot raise IQ.

Fact: Social intervention has been shown to raise IQ at every year of childhood.


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.


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:

Socioeconomic status change and IQ of adopted children (16)

Biological   Adoptive
Parent SES   Parent SES   Average IQ
Low          Low           92 points
Low          High         104
High         Low          108
High         High         120

So the difference between being raised in a lower and upper class home is 12 IQ points! Defenders of The Bell Curve might remind everyone here that this chart simply confirms what the book admits repeatedly: that both genes and environment play a role in forming IQ. However, we mustn't forget Herrnstein and Murray's original claim: that social intervention does not result in permanent gains. This chart shows them to be wrong. (When you stop to think of it, it was quite contradictory for them to assert that IQ is 40 percent environmental, yet can't be changed by social intervention.)

A few qualifications about the study bear mentioning: the sample size was very small (38 children), and it is unknown exactly how rich or poor the parents were, or what their IQs were. Nonetheless, both French studies come to the same conclusion. And for whatever reason, Herrnstein and Murray have chosen not to dispute their findings (as they have so energetically with other studies). Instead, they raise a different sort of objection: that the lessons of these studies cannot be applied to everybody. They write:

This is a truly remarkable statement. First of all, it's a political and economic argument, not a biological one. It abandons their original claim that social intervention cannot raise IQs, and now argues that we do not possess the political will or economic ability to do so.

But this is false. We may not know how to equalize environments upward (notice the inclusion of the last word), but we certainly know how to equalize them: through greater progressivity in the tax code. Conservatives are quick to denounce this as ruinous economics, but we should remember that the most prosperous era in U.S. history -- the 1950s and 60s -- was also its most equal, with the top tax rate hitting 91 percent, and a record low Gini index of .348 in 1967. Nor can conservatives object that lowering the opulence of the rich threatens to lower their IQs. There is a point beyond which earning even more income does not result in further gains in children's IQs, and when the top 1 percent of America owns nearly 40 percent of its wealth, it's safe to say that point was reached a long time ago. Nor can conservatives object that the rich do not have enough money to raise everyone out of poverty. In 1991, those making more than $200,000 a year approximately constituted the top 1 percent. This group reported $403 billion in Gross Adjusted Income, and paid $100 billion of that taxes -- an effective rate of 25 percent. Suppose that were raised to 70 percent, which would have brought in $282 billion in taxes. Thatís an extra $182 billion, which could have given a pay raise of over $5,000 to each of the nationís 35.7 million people in poverty. Essentially, this would have eliminated poverty in America. (Remember, most of the nation's poor are already working; the extra $5,000 would easily boost them out of the danger zone.) (18) And we could accomplish this without changing the taxes of 99 percent of Americans.

The economic ability is there; all that we need now is the political will to do it.

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1. Richard Herrnstein and Charles Murray, The Bell Curve (New York: Simon & Schuster, 1994), p. 389.

2. Quoted in Don Lattin, "'Bell Curve' Called Political, Not Scientific: Psychologists examine race-IQ controversy," The San Francisco Chronicle, Friday, August 11, 1995, A6.

3. Personal communication with Judith Aissen, 1987, University of California - Santa Cruz.

4. Richard Nisbett, Letter to the editor, Commentary, August 1995, vol. 100, no. 2; Nisbett, "Race, IQ and Scientism," p. 45 in Steven Fraser, ed., The Bell Curve Wars (New York: HarperCollins, 1995).

5. C.T. Ramey, D.M. Bryant, B.H. Wasik, J.J. Sparling, K.H. Fendt and L.M. LaVange, "Infant health and development program for low birth weight, premature infants: Program elements, family participation, and child intelligence," Pediatrics 3, 1992, pp. 4343-465.

6. C.T. Ramey, D.M. Bryant, and T.M. Suarez, "Preschool compensatory education and the modifiability of intelligence: A critical review," pp. 247-96 in D. Detterman, ed., Current Topics in Human Intelligence (Norwood, NJ: Ablex, 1985). R. McKey, L. Condelli, H. Ganson, et al., "The impact of Head Start on children, families, and communities," Final report of the Head Start Evaluation, Synthesis, and Utilization Project (Washington, DC: U.S. Department of Health and Human Services, 1985). K. White and G. Casto, "An integrative review of early intervention efficacy studies with at-risk children: Implications for the handicapped," Analysis and Intervention in Developmental Disabilities 5, 1985, pp. 7-31.

7. R. Haskins, "Beyond Metaphor: The efficacy of early childhood education," American Psychologist 44, 1989, pp. 274-282. R.H. McKey, The Impact of Head Start on Children, Families, and Communities, A.N. Smith and S.S. Aitken, eds., (Washington D.C.: U.S. Department of Health and Human Services, 1985) H.H. Spitz, The Raising of Intelligence: A Selected History of Attempts to Raise Retarded Intelligence (Hillsdale, N.J.: Lawrence Erlabaum Associates, 1986). E. Zigler and S. Muenchow, Head Start: The Inside Story of America's Most Successful Educational Experiment (New York: Basic Books, 1992).

8. S.L. Ramey and C.T. Ramey, "Early educational intervention with disadvantage children -- to what effect?" Applied and Preventative Psychology 1, 1992, pp. 131-40. Head Start and Beyond (New Haven: Yale University Press, 1993).

9. R.S. Nickerson, "Project Intelligence: An Account and some reflections," pp. 83-102 in M.Scwebel and C.A. Maher, eds., Facilitating Development: International Perspectives, Programs, and Practices (New York: Haworth Press, 1986).

10. "Head Start Study Blames Schools For Fading Effect," Report on Education Research, March 29, 1995. A copy of the report, "Where Do Head Start Attendees End Up? One Reason Why Preschool Effects Fade Out," is free from American
Educational Research Association, Outreach, 1230 17th St.
NW, Washington, D.C. 20036-3078, (202)223-9485.

11. William Bennett, Schools that Work (Washington D.C.: U.S. Department of Education, 1987).

12. D. Benton and G. Roberts, "Effect of vitamin and mineral supplementation on intelligence of a sample of schoolchildren," Lancet 1, 1988, pp. 140-44.

13. S. Schoenthaler, S. Amos, H. Eysenck, E. Peritz and J. Yudkin, "Controlled trial of vitamin-mineral supplementation: Effects on intelligence and performance," Personality and Individual Differences 12, 1991, pp. 351-62.

14. S.Scarr and R. Weinberg, "The Minnesota adoption studies: Genetic differences and malleability," Child Development 54, 1983, pp. 260-67.

15. M. Schiff, M. Duyme, A. Dumaret and S. Tomkiewicz, "How much could we boost scholastic achievement and IQ scores? A direct answer from a French adoption study," Cognition 12, 1982, pp. 165-96. M. Schiff and R. Lewontin, Education and Class: The Irrelevance of IQ Genetic Studies (Oxford: Clarendon, 1986).

16. C. Capron and M. Duyme, "Assessment of effects of socioeconomic status on IQ in a full cross-fostering study," Nature 340, 1989, pp. 552-3.

17. Herrnstein and Murray, pp. 412-13.

18. Income figures from Internal Revenue Service, Individual Income Tax Returns, 1991. Poverty figures from U.S. Bureau of the Census, Current Population Reports, P60-188. In 1991, the poverty rate for all unrelated individuals was $6,932. For a family of three, it was $10,860. But three times $5,000 (our hypothetical pay raise for each poor person) is $15,000, so families in poverty would escape it completely.