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Breaking "The Code of Infancy"...
Actually, it isn't quite correct to claim that the learning processes of babies are better or worse than those of adults. It's just that they learn differently and may have different capacities to remember a variety of things, says Spear, distinguished professor of psychology at State University of New York at Binghamton.
Spear's research has been funded since his graduate school days at Northwestern University, where he earned both his MS and PhD degrees in experimental psychology. Sponsors include the National Science Foundation, the National Institute of Alcohol Abuse and Alcoholism, and the National Institute of Mental Health, which is funding his current research.
He says all of his research is collaborative. He works both with psychologists at the university and with researchers and students from other institutions.
A quick glance at Spear's office shows other passions that guide his life. The numerals 3, 6, 9, and 12 on his wall clock have been replaced by 15, 30, 40 and Game. Pictures of his two now-grown children fill the bulleting board behind his desktop computer. His experimental animals receive sweet water to reinforce desired behavior, but he and his fellow researchers enjoy another reward: the chocolate chip cookie canister on his worktable is empty except for crumbs.
Learning to communicate with the newborn, to find out what an infant animal is actually learning, his occupied Spear for the last 15 years. A first step was to study the animal's ecological niche, to learn which tastes, odors, and touches dominate its early years.
Next, Spear studied the circumstances of learning. He found, for instance, that taking an infant from its home to test its learning and memory was itself an impediment to some learning. Like human infants, infant rats are distressed when taken from their home and parents. Merely surrounding the testing apparatus with the odors of home enhanced some learning, yet delayed other learning.
Helping memory along
Now, says Spear, he and his colleagues are attempting to "break the code of infancy."
"We have learned a number of ways in which forgetting can be alleviated by presenting to the animal (or human) particular 'reactivation treatments' or reminders when remembering is required," Spear says. "The basis of this treatment is, in essence, to re-present aspects of the critical episode as they were originally stored in memory. We think that ultimately we might be able to alleviate infantile amnesia if we can first determine what is originally stored in memory by the infant."
After nearly 25 years, Spear says he's on the threshold of really understanding infantile amnesia.
"And that would have several benefits," says Spear. "First, the process of psychotherapy would be greatly facilitated. Ready access to childhood memories would, in short, save psychotherapists a good deal of time and patients a good deal of money."
Second, "Ready access to what we learned in childhood and its more efficient integration with what must be learned at older ages could influence the effectiveness of learning as adults," he adds.
Forgetting through the ages
Infantile amnesia is a phenomenon that has intrigued psychologists, psychobiologists, and psychoanalytic theorists since the days of Freud, who coined the term. For Freudian psychotherapists, the quest was crucial, since so much depended on retrieving those early memories which they believed contained the roots of normal, neurotic, and psychotic adult behavior.
But Freud's explanation of infantile amnesia - that people repress early memories voluntarily as they grow older and become embarrassed by their socially unacceptable nature - is easily debunked, says Spear. "It can't be right," he says, "because all memories are repressed, both good and bad. And animals show the same behavior, even though they have no sense of what's socially acceptable or embarrassing."
Actually, theories about forgetting go back to the sixth century BC when Parmenides suggested that people forget when the wrong combination of light, dark, cold, and heat affect the body. A hundred years later, Diogenes refined the theory, attributing forgetfulness to improper distribution of air in the body. He supported his claim by noting that people breathe a sigh of relief after remembering something they've forgotten.
Since Freud, the theories about forgetting have gotten more sophisticated, but no less numerous. The basis of many is the assumption that no memory is lost forever, that it can be retrieved by finding the right cue.
"It's easy to generate theories," Spear says. "The problem is to generate data to support them."
Validating memory
The problem of studying the kind of forgetting that occurs over long periods of brain growth is compounded by the inability to experiment with humans. "You can't manipulate the brain, you can't study strong emotional events, the events that really shape one's behavior, because you can't induce trauma," says Spear. And obviously, you can't teach a subject something at the age of two, then wait for twenty years to see if he or she remembers it.
Scientists studying memory and forgetting are also plagued by the unreliability of verbal reports. Whether intentional or not, memories are altered by after-the-fact events or by hearing people relate what happened. "For a good study, you need objective observers who can report that the episode actually occurred," says Spear.
Spear works with that workhorse of experimental psychologists - the rat - because the growth rate of its brain is quick, from immaturity to adulthood in about a month. "We know what happens day by day, so you can see striking effects in a 24-hour period," he notes.
But finding a suitable experimental animal didn't help matters much until it was coupled with the discovery of ways to teach baby animals significant tasks. A landmark symposium held at Binghamton in 1977, "The Ontogeny of Learning and Memory," heralded the discovery of ways to study an animal's learning from the day it is born - and even before it's born, adds Spear.
Infant cognition
A fundamental finding about infantile amnesia is that "in spite of an equivalent degree of learning, younger animals forget more rapidly." This observation came from watching rats find their way about a maze to obtain food, for example. But this method has some disadvantages for Spear's work with newborn animals "because it's hard to tell exactly what stimuli control their behavior. Also, with the very young, we are dealing with an animal that can exhibit almost no instrumental behavior, will not move about in a maze, and cannot push a lever," he says.
Spear adapted the testing process to his young subjects, using a simplified Pavlovian conditioning and introducing stimuli that a newborn can process - smells, tastes, degrees of temperature, or softness or roughness.
Spear has determined that a baby animal learns more than just the pairing of, say apple juice and feeling ill. the animal learns the larger context as part of the memory - his surroundings, his physical well being, how he was handled just before feeding.
Baby animals also seem to learn more redundant information than adults, aspects of an episode for which learning is not really "required" in order to remember it, says Spear. But such redundant information does affect memory, he adds, depending on whether it's pleasant or unpleasant.
Another difference is that while an adult might see the world in terms of differentiated segments, an infant sees much of his world in single units. Infants must learn to determine what aspects go together and what aspects must be kept apart to form the objects of the world, says Spear.
Spear found one aspect of the process particularly intriguing. Infants must learn to separate their senses; they must determine that a touch is not the same as a taste and that smelling something is different than seeing it. But infants seem to "transfer information across modalities," confusing taste with smell, and mixing other senses as well, says Spear.
"I think during the next five to ten years," Spear concludes, "we'll be able to take what we've learned about infant learning and explain infantile amnesia. When we understand the entire array of what is acquired in infancy, we may have the key to retrieving memories at any age."
by Lee Shepherd
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