Transcription
Around the turn of the century, the great Russian physiologist Ivan Pavlov made an accidental discovery that was to become a landmark in the field of learning. Pavlov was studying the salivation reflex in dogs as part of his research on digestion. He noticed that after the dogs had been brought to the laboratory many times, they would start to salivate even before food was given. What had altered the dog's inborn salivation reflex?
Pavlov was fascinated and changed the direction of his research to focus on what he called conditional reflexes. Pavlov knew that placing food in the dog's mouth naturally caused salivation: the unconditioned stimulus, food, produced the unconditioned response, salivation. Through a series of ingenious experiments, he found that if a new and unrelated stimulus, like a bell, was repeatedly sounded before the food was given, the dogs would learn to salivate when they heard the bell, even when no food followed. The conditioned stimulus, the bell, produced the conditioned response, salivation. Moreover, almost any type of stimulus, when paired with food, could produce salivation. This process of learning by association became known as classical conditioning.
Pavlov's contribution in introducing the concept of classical conditioning was to bring to us an understanding of how we learn by association, how we learn that one thing leads to another. This has been particularly important in helping us understand how certain autonomic or automatic physiological responses come to occur in new situations in which they didn't normally occur.
One practical application of classical conditioning is the work of Dr. John Garcia, who confronted the problem of coyotes who would attack farmers' livestock, destroying these predators upsets the delicate ecological balance. But how else could these animals be controlled? Psychologists John Garcia and Carl Gustavson developed a new strategy based on the concepts of classical conditioning. Lamb meat is laced with lithium chloride, a chemical that produces nausea when eaten. The treated meat is then wrapped in sheep hide and put out as bait near grazing flocks. When the coyotes eat the bait, they immediately become sick and vomit. The predators quickly learn to associate sheep with nausea and actively avoid the animals. More and more ranchers are using this approach to protect their flocks while preserving the delicate ecology of the range lands.