A number of phenomena characterize both classical conditioning and operant conditioning, and there are several terms and concepts common to both kinds of learning.

Response Acquisition

In classical conditioning, responses occur naturally and automatically in the presence of the unconditioned stimulus. During the phase of the learning process called response acquisition, these naturally occurring responses are attached to the conditioned stimulus by pairing that stimulus with the unconditioned stimulus. Intermittent pairing reduces both the rate of learning and the final level of learning achieved.

In operant conditioning, response acquisition refers to the phase of the learning process in which desired responses are followed by reinforcers. A Skinner box is often used to limit the range of available responses and thus increase the likelihood that the desired response will occur. To speed up this process and make the occurrence of a desired response more likely, motivation may be increased by letting the animal become hungry; the number of potential responses may also be reduced by restricting the animal's environment.

For behaviors outside the laboratory, which cannot be controlled so conveniently, the process of shaping is often useful: Reinforcement is given for successive approximations to the desired behavior. However, there are differences among species in what behaviors can be learned and the circumstances under which learning will take hold.

Extinction and Spontaneous Recovery

Figure 5-6

If the unconditioned stimulus and the conditioned stimulus are no longer paired, extinction occurs, meaning the strength and/or frequency of the learned response diminishes. When Pavlov's dogs received no food after repeatedly hearing the bell, they ceased to salivate at the sound of the bell. However, after a while, this extinguished response may reappear without retraining in a process called spontaneous recovery. Extinction is complete when the subject no longer produces the conditioned response.

Extinction occurs in operant conditioning when reinforcement is withheld. However, the ease with which a behavior is extinguished varies according to several factors: the strength of the original learning, the variety of settings in which learning takes place, and the schedule of reinforcement used during conditioning. Especially hard to extinguish is behavior learned through punishment rather than reinforcement.

Generalization and Discrimination

In classical conditioning, situations or stimuli may resemble each other enough that the learners will react to one the way they have learned to react to the other through a process called stimulus generalization. On the other hand, the process of stimulus discrimination enables learners to perceive differences among stimuli so that not all loud sounds, for example, provoke fear.

Just as in classical conditioning, responses learned through operant conditioning can generalize from one stimulus to other, similar stimuli. Response generalization occurs when the same stimulus leads to different but similar responses. Discrimination in operant conditioning is taught by reinforcing a response only in the presence of certain stimuli.