chapter  3
Adaptational Aspects of Conditioning
Pages 44

From the very earliest days of Pavlov's investigations of classical conditioning, it has been known that the conditioning process involves considerably more than the basic finding that a previously indifferent conditioned stimulus (CS) becomes an effective elicitor of learned responses following so me number of appropriately paired presentations with an originally effective unconditioned stimulus (US). N otwithstanding the enormous biological significance of the initial conditioned association, in Pavlov's view it was only the opening movement in a subtle and dynamic interplay of excitatory and inhibitory mechanisms by means of which, " ... a continuous and most exact adaptation of the organism to its environment is effected" (Pavlov, 1927, p. 106).