Further comment on classical and instrumental conditioning

Hebb's interesting discussion approaches but skirts an intriguing relation between instrumental and classical conditioning often considered but not yet explicitly stated. The Pavlovian procedure of using UCS to elicit a response which then can occur to CS is considered by Hebb to be actually an example of instrumental learning. That is, UCS becomes a reinforcement as a direct result of the response; therefore, the response is acquired by reinforcement. This distinction will apply when considering aversive conditioning. But a heuristic advantage may lie in considering that the principle of control of behaviour by discriminative stimuli and by varying the schedule of reinforcement may apply equally well to both classical and instrumental conditioning situations.