Story of Psychology - Morton Hunt [243]
At the end of two years McGraw gave Jimmy intensive training to see whether he could catch up to Johnny; he never fully did. But psychologists who have reviewed her data feel that Johnny’s training gave him only a small and largely temporary advantage over Jimmy. McGraw did not agree; many years later—after experiments like hers, which stunt a child’s development, had come to be considered gravely unethical—she asserted that although Jimmy had caught up in most ways, even as a young adult he still had less ease and grace of physical movement than Johnny.56 What this proves, however, is hard to say, since it turned out that the boys were fraternal twins, not identicals. The only safe conclusion is that intensive physical training can push a child to achieve physical skills ahead of schedule and that most of the gain is temporary.
A more drastic experiment was conducted, also beginning in 1932, by Wayne Dennis, then at the University of Virginia. From an indigent Baltimore woman he obtained her fraternal twin girls, Del and Rey, when they were five weeks old, and, with his wife’s help, reared them in his home for over a year. His plan was to deprive them of all stimulation and learning to see what forms of behavior arose spontaneously with maturation. In a journal article, Dennis reported, with no qualms or apologies, how he carried out his experiment:
During the first six months we kept a straight face in the babies’ presence, neither smiling nor frowning, and never played with them, petted them, or tickled them, except as these actions reasonably were incorporated into routine experiments…To restrict practice which might influence sitting, the infants were kept almost continually on their backs in the cribs.57
They were not even allowed toys or the sight of each other for eleven months. (There was a screen between their cribs.)
The results, Dennis claimed, showed that “the infant within the first year will ‘grow up’ of his own accord,” as evidenced in the twins by such behavior as laughing, bringing their feet to their mouths, and crying in response to sounds at about the same ages as children reared normally. But they lagged far behind other children in crawling, sitting, and standing. After fourteen months Dennis gave them a period of training that, he said, quickly brought them up to normal. By his own admission, however, Rey could not walk without holding on until her seventeenth month and Del not until her twenty-sixth month.
The twins spent the rest of their childhood in institutions and the homes of relatives. Although Dennis claimed he had brought them up to par, he later had good reason to doubt it. In Iran he studied orphanage children and found that many of them, neglected and given little attention, were developmentally retarded at two years and remained somewhat so in adolescence. But he never followed up on Del and Rey to see how they turned out; perhaps he did not want to know.
Such experiments, rare seventy years ago, are nonexistent today; after the civilized world learned of the “medical research” conducted by Nazi doctors in concentration camps, legal constraints on research with human subjects became stringent. But developmentalists have pursued their goals in other ways. One is by experimenting with animals. Much as behaviorists sought principles of learning in rats that would be relevant to learning in humans, developmentalists sought principles of maturation in animals that would apply to humans.
In one well-known case, newly hatched goslings, which were thought to trail after their mother instinctively, were taught by the German ethologist and Nobelist