Science - May 1982 pp. 70-71 In a dimly lit room, a two-year-old child sits on his mother's lap, attention riveted on a disembodied hand emerging from the black curtains of something resembling a puppet theater. The hand picks up a wand and moves toward three large light bulbs. When the wand touches one of the bulbs, they all light up. The hand retreats. A few minutes later it emerges again, palm down. It slowly moves towards the bulbs, and they go out. The little boy begins to wriggle around but quiets as the sequence is repeated, six times in all. Next comes a change: The wand appears alone and touches a bulb as before, but this time none lights up until after the wand has disappeared, when all light up again. This happens three times. Then the original sequence returns. Meanwhile electrodes on the child's chest send continuous measurements of his heart rate to an eight-channel polygraph machine in another room. There the squiggles are analyzed for evidence of mental effort, which registers as an increase in the heart rate, or recognition-the so-called Ah-ha! reaction-which shows up as a deceleration of six heartbeats or more. Observers hidden behind a one-way mirror tick off reactions such as a smile when the hand reappears, a gesture or word of recognition as it comes back yet again, a change of expression when the wand comes on alone. The hand theater is part of a new kind of intelligence test for babies developed by psychologist Philip R. Zelazo and pediatrician Richard B. Kearsley at the Center for Behavioral Pediatrics and Infant Development of the Tufts-New England Medical Center in Boston. Children who are handicapped or too young to talk are among the most difficult to assess accurately. If they have trouble hearing or using their arms and hands, traditional tests may suggest they are mentally defective when in fact they are normal, according to Zelazo and Kearsley. These new intelligence tests measure a child's ability to pay attention, to notice similarities and differences, and to form memories-in other words, to gather and process information- where other tests measure only the ability to answer questions correctly through gestures and language. During the past four years, Zelazo and Kearsley's new test has proved far more accurate than standard tests in diagnosing the mental abilities of children between the ages of one and three who have cerebral palsy, missing limbs, or developmental problems. For example, one little girl of 20 months neither walked nor talked. She cried all the time and had trouble eating because of an ulcerated tongue. Standard tests indicated she was mentally retarded. In the hand theater, however, the little girl responded exactly as she should for her age. When the light bulb sequence was repeated for the third time, her heart rate went down, indicating that she recognized it. In another test, she was able to recognize the difference between a real spoken sentence such as "Drink the good milk, and a nonsense sentence, "Plice la delf klim" (Her heart rate went up at that one, indicating her puzzlement over the strange sounds.) After reassuring the parents that their daughter's intelligence was normal, Zelazo and Kearsley taught them how to reward the child with a small cookie for each spoken word while ignoring her crying. The girl made rapid progress. She began to smile. Within 10 months she was speaking and walking normally. At the age of three, she entered a regular nursery school where she is doing well. In a recent study Zelazo and Kearsley found that 33 of the 44 children with developmental delays were not mentally retarded according to their tests. "So our goal was to bring them up to normal functioning. With 14 of them, we succeeded within 10 months of treatment," says Kearsley. By contrast, those who did poorly on the Zelazo-Kearsley test appeared to have some real neurological handicaps. The training they received from their parents during the 10 months of treatment improved their behavior and mental development but did not bring them up to par.
Zelazo and Kearsley are currently adapting their project for computers. Eventually, they hope, computers will be able to both administer and grade the test, making it possible to identify the thousands of children with developmental problems who are misdiagnosed as retarded every year.
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