At first, Pavlov treated the dog’s drooling as just an annoying secretion. But he quickly realized that his student had stumbled onto an important phenomenon, one that Pavlov came to believe was the basis of a great deal of learning in human beings. He called that phenomenon a “conditional” reflex- conditional because it depended on environmental conditions. Later, an error in the translation of his writings transformed “conditional” into “conditioned,” the word most commonly used today.
Pavlov soon dropped what he had been doing and turned to the study of conditioned reflexes, to which he devoted the last three decades of his life. Why were his dogs salivating to aspects of the environment other than the food?
Pavlov initially speculated about what his dogs might be thinking and feeling to make them drool before getting their food. Was the doggy equivalent of “Oh boy, this means chow time” going through their minds? Eventually, however, he decided that such speculation was pointless. Instead, he focused on analyzing the environment in which the conditioned reflex arose. The original salivary reflex, according to Pavlov, consisted of an unconditioned stimulus, food, and an unconditioned response, salivation. By an unconditioned stimulus, Pavlov meant an event or thing that elicits a response automatically or reflexively. By an unconditioned response, he meant the response that is automatically produced.
The neutral stimulus then becomes a conditioned stimulus, which elicits a learned or conditioned response that is usually similar to the original, unlearned one. In Pavlov’s laboratory, the sight of the food dish, which had not previously elicited salivation, became a CS for salivation.
The procedure by which a neutral stimulus becomes a conditioned stimulus became known as classical conditioning, also called Pavlovian or respondent conditioning Pavlov and his students went to show that all sorts of things can become conditioned stimuli for salivation if they are paired with food: the ticking of a metronome, the musical tone of a bell or tuning fork, the vibrating sound of a buzzer, a triangle drawn on a large card, even a pinprick of an electric shock. And since Pavlov’s day, many automatic, involuntary responses besides salivation have been classically conditioned- for example, heartbeat, stomach secretions, blood pressure, reflexive movements, blinking, and muscle contractions. The optimal interval between the presentation of the neutral stimulus and the presentation of the US depends on the kind of response involved; in the laboratory, the interval is often less than a second.
For classical conditioning to be most effective, the stimulus to be conditioned should precede the unconditioned stimulus rather than follow it or occur at the same time. This makes sense, because in classical conditioning, the conditioned stimulus becomes a kind of signal for the unconditioned stimulus. It enables the organism to prepare for an event that is about to happen. In Pavlov’s studies, for instance, a bell or a buzzer was a signal that meat was coming, and the dog’s salivation was preparation for digestion food.
If a dog can learn to salivate to the ringing of a bell, so can you. In fact, you probably have learned to salivate to the sound of a lunch bell, not to mention the phrase hot fudge sundae, “mouth-watering” pictures of food in magazines, and a voice calling out “Dinner’s ready!” But the role of classical conditioning goes far beyond the learning of simple observable reflexes; conditioning affects us every day in many ways.
