Abstract
Three groups of rats (n = 12) were given unsignalled avoidance training in a shuttlebox. Two groups were given three days of Pavlovian fear conditioning. Group 1 was trained with a tone (CS1) and a tone-light compound (CS2) followed immediately by shock. Group 2 was trained with CS1 followed immediately by shock and CS2 followed 5 sec. later by shock. Group 3 received only unsignalled avoidance sessions. When CS1 and CS2 were superimposed upon unsignalled avoidance both CSs accelerated avoidance responding for Group 1, CS1 accelerated responding and CS2 depressed responding for Group 2, and neither CS significantly altered the rate of responding for Group 3. Results can be interpreted in part in terms of Denny's (1971) relaxation theory.
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