Classical Conditioning & Operant Conditioning

CLASSICAL CONDITIONING OPERANT CONDITIONING

Acquisition

The acquisition phase is the initial learning of the conditioned response--for example, the dog learning to salivate at the sound of the bell. Several factors can affect the speed of conditioning during the acquisition phase. The most important factors are the order and timing of the stimuli. Conditioning occurs most quickly when the conditioned stimulus (the bell) precedes the unconditioned stimulus (the food) by about half a second. Conditioning takes longer and the response is weaker when there is a long delay between the presentation of the conditioned stimulus and the unconditioned stimulus. If the conditioned stimulus follows the unconditioned stimulus--for example, if the dog receives the food before the bell is rung--conditioning seldom occurs.

Shaping

Shaping is a reinforcement technique that is used to teach animals or people behaviours that they have never performed before. In this method, the teacher begins by reinforcing a response the learner can perform easily, and then gradually requires more and more difficult responses. For example, to teach a rat to press a lever that is over its head, the trainer can first reward any upward head movement, then an upward movement of at least one inch, then two inches, and so on, until the rat reaches the lever. Psychologists have used shaping to teach children with severe mental retardation to speak by first rewarding any sounds they make, and then gradually requiring sounds that more and more closely resemble the words of the teacher. Animal trainers at circuses and theme parks use shaping to teach elephants to stand on one leg, tigers to balance on a ball, dogs to do backward flips, and killer whales and dolphins to jump through hoops.

Extinction

Once learned, a conditioned response is not necessarily permanent. The term extinction is used to describe the elimination of the conditioned response by repeatedly presenting the conditioned stimulus without the unconditioned stimulus. If a dog has learned to salivate at the sound of a bell, an experimenter can gradually extinguish the dog's response by repeatedly ringing the bell without presenting food afterward. Extinction does not mean, however, that the dog has simply unlearned or forgotten the association between the bell and the food. After extinction, if the experimenter lets a few hours pass and then rings the bell again, the dog will usually salivate at the sound of the bell once again. The reappearance of an extinguished response after some time has passed is called spontaneous recovery. Extinction

As in classical conditioning, responses learned in operant conditioning are not always permanent. In operant conditioning, extinction is the elimination of a learned behaviour by discontinuing the reinforcer of that behaviour. If a rat has learned to press a lever because it receives food for doing so, its lever pressing will decrease and eventually disappear if food is no longer delivered. With people, withholding the reinforcer may eliminate some unwanted behaviours. For instance, parents often reinforce temper tantrums in young children by giving them attention. If parents simply ignore the child's tantrums rather than reward them with attention, the number of tantrums should gradually decrease.

Generalization

After an animal has learned a conditioned response to one stimulus, it may also respond to similar stimuli without further training. If a large black dog bites a child, the child may fear not only that dog, but also other large dogs. This phenomenon is called generalization. Less similar stimuli will usually produce less generalization. For example, the child may show little fear of smaller dogs. Generalization and discrimination

Generalization and discrimination occur in operant conditioning in much the same way that they do in classical conditioning. In generalization, people perform a behaviour learned in one situation in other, similar situations. For example, a man who is rewarded with laughter when he tells certain jokes at a bar may tell the same jokes at restaurants, parties, or wedding receptions.

Discrimination

The opposite of generalization is discrimination, in which an individual learns to produce a conditioned response to one stimulus but not to another stimulus that is similar. For example, a child may show a fear response to freely roaming dogs, but may show no fear when a dog is on a leash or confined to a pen Discrimination

Discrimination is learning that a behaviour will be reinforced in one situation but not in another. The man may learn that telling his jokes in church or at a serious business meeting will not make people laugh. Discriminative stimuli signal that a behaviour is likely to be reinforced. The man may learn to tell jokes only when he is at a loud, festive occasion (the discriminative stimulus). Learning when a behaviour will and will not be reinforced is an important part of operant conditioning.

Punishment

Whereas reinforcement strengthens behaviour, punishment weakens it, reducing the chances that the behaviour will occur again. As with reinforcement, there are two kinds of punishment, positive and negative. Positive punishment involves reducing a behaviour by delivering an unpleasant stimulus if the behaviour occurs. Parents use positive punishment when they spank, scold, or shout at children for bad behaviour. Societies use positive punishment when they fine or imprison people who break the law. Negative punishment, also called omission, involves reducing a behaviour by removing a pleasant stimulus if the behaviour occurs. Parents' tactics of grounding teenagers or taking away various privileges because of bad behaviour are examples of negative punishment.

Considerable controversy exists about whether punishment is an effective way of reducing or eliminating unwanted behaviours. Careful laboratory experiments have shown that, when used properly, punishment can be a powerful and effective method for reducing behaviour. Nevertheless, it has several disadvantages. When people are severely punished, they may become angry, aggressive, or have other negative emotional reactions. They may try to hide the evidence of their misbehaviour or escape from the situation, as when a punished child runs away from home. In addition, punishment may eliminate desirable behaviours along with undesirable ones. For example, a child who is scolded for making an error in the classroom may not raise his or her hand again. For these and other reasons, many psychologists recommend that punishment be used to control behaviour