Page 31 - History of Psychology

Food (unconditioned stimulus) --> Salivation (unconditioned response)
Footsteps (neutral stimulus) --> Food (unconditioned stimulus) --> Salivation

(unconditioned response)
Footsteps (conditioned stimulus) --> Salivation (conditioned response)

Excitation and Inhibition.
Pavlov believed that all central nervous system activity could be characterized as
either excitatory or inhibitory. All behavior is reflexive, that is, induced by a
preceding stimulus. If not modified by inhibition, the unconditioned stimulus and
the conditioned stimulus will produce an unconditioned and a conditioned reflex,
respectively. The important point is that we are constantly subjected to a variety
of stimuli, some of which tend to elicit behavior and some tend to inhibit behavior.
If a conditioned stimulus is continuously given to an organism and is no longer
followed by an unconditioned stimulus, the conditioned response will gradually
diminish and eventually disappear, at which point it is said to have occurred. If a
period of time is allowed to elapse after extinction and the conditioned stimulus is
presented again, the stimulus will elicit a conditioned response. This is called

spontaneous recovery. For example, if the tone (CS) is consistently followed by
the serving of food powder (AS), an organism will eventually salivate when the
tone alone is served (CR). If the tone is then presented but not followed by food
powder, the magnitude of the conditioned response will gradually decrease, and
eventually the tone will no longer elicit the conditioned response (extinction).
However, after a delay—even without further pairing of tones and food powders—
the tones will again elicit the conditioned response (spontaneous recovery).

This phenomenon is demonstrated when, after extinction has occurred,
presenting a strong and irrelevant stimulus to the animal causes a conditioned
response to return. The assumption is that fear caused by a strong stimulus
replaces the inhibitory process, thereby allowing the return of the conditioned
response.

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