Story of Psychology - Morton Hunt [244]
Eckhard Hess, an American, built a moving, quacking, decoy mallard, and put mallard ducklings in its presence. If he did so as soon as they were hatched, half of them became attached to it, but if he first did so when they were thirteen to sixteen hours old, over 80 percent became attached to it. What looked like an instinct was a more complex phenomenon: the nervous system of the duckling is wired to respond to moving objects but is most readily “imprinted” on a particular target at a special time slot in the maturation process.59
As a result of these findings, in the 1970s some developmentalists and pediatricians came to believe that it is in the first hours after birth that the mother-infant bond can best be formed. They advised mothers to cuddle the newborn against their naked body for a while immediately after delivery instead of having it whisked away to be cleaned up and parked in a bassinet in the hospital nursery. But while some subsequent research showed stronger infant-mother bonding when this was done, it was the mother who was bonded. Much other research has shown that the infant’s attachment to the mother (or father or other principal caretaker) develops over a period of four to five months in response to innumerable acts of caretaking and expressive attention.60
Much maturation research is concerned with physical skills and physical attributes, and adds little to our knowledge of the growth of the mind. But research on the development of perceptual abilities has been providing solid factual answers, in place of speculation, to the ancient central question of psychology: How much is due to nature and how much to nurture (or, in developmental terms, to maturation and to learning)?
The work has been focused on early infancy, when perceptual abilities evolve rapidly; its aim is to discover when each new ability first appears, the assumption being that at its first appearance, the new ability arises not from learning but from maturation of the optic nervous structures and especially of that part of the brain cortex where visual signals are received and interpreted.
Much has been learned by simply watching infants—noting, for instance, at what age they can fix their gaze on nearby objects. But such observations leave many questions unanswered. What, exactly, do very young infants see? Not much, apparently; their eyes often seem unfocused and do not even track a moving object. On the other hand, mothers know that their infants gaze steadily at them while they nurse. Since we cannot ask them what they see, how can we find out?
In 1961, the psychologist Robert Fantz devised the ingenious method of doing so briefly mentioned earlier. He designed a stand in which, on the bottom level, the baby lies on his back, looking up. A few feet above is a display area where the experimenter puts two large cards, each containing a design—a white circle, a yellow circle, a bull’s-eye, a simple sketch of a face. The researcher, peering down through a tiny peephole (so that he is not visible), can watch the movement of the baby’s eyes and time how long they are directed at one or the other of each pair of patterns. Fantz found that at two months babies looked twice as long at a bull’s-eye as at a circle of solid color, and twice as long at a sketch of a face as at a bull’s-eye. Evidently, even a two-month-old can distinguish major differences and direct his gaze toward what he finds more interesting.61
Using this technique and others of a related nature, developmental psychologists have learned a great deal about what infants see and