Behavior: Nurturing Intelligence

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Of the nation's 6,000,000 mentally retarded children and adults, 80% have no detectable abnormality of the central nervous system. How then to explain their inadequacy?

In the bitter controversy over the reasons for low IQs, some psychologists, notably Arthur Jensen and Richard Herrnstein (TIME, Aug. 23) put the blame largely on inferior genes. Others believe that environment—especially the environment of the ghetto —is of primary importance. A recent report on the first five years of an experiment with mentally retarded mothers and their children in Milwaukee supports the latter view. It also offers persuasive evidence that mental retardation in the offspring of mentally retarded mothers can be prevented.

To recruit subjects for their experiment, University of Wisconsin Psychologists Rick Heber and Howard Garber went to a slum, which typically is the section of any city with the highest concentration of the mentally retarded. Initial testing showed that retarded mothers are likely to have retarded children, but did not reveal the reason. Heber and Garber suspected that it was the way in which the retarded mothers dealt with their children that made the critical difference between them and the children of equally impoverished mothers of normal intelligence.

The psychologists' aim was to wipe out that difference. Choosing 40 retarded mothers with newborn babies, all black, they assigned them randomly to two groups with 20 mothers and infants in each. For the control group, nothing special was done. In the experimental group, the mothers were given job training and taught homemaking and baby care. Their babies, beginning at three months of age, were picked up every morning and taken to the university. There, "infant stimulation teachers" fed, bathed and taught them until 4 p.m.

Tested at intervals, the 20 "stimulated" children have proved "distinctly superior" to the youngsters who stayed at home. They have IQs averaging about 125, compared with scores of 75 or less for their mothers and about 95 for untreated children of similar background.

Yet Heber and Garber admit that the experimental children have become "test-wise" and that the differences between the two groups could disappear as they grow older. Still, the psychologists conclude, the youngsters have accomplished so much that "it is difficult to conceive of their ever being comparable to the lagging control group."