Stimulus intensity effects and second-order response acquisition in Pavlovian fear conditioning

The present series of studies was designed to a) determine if, following Pavlovian conditioning of a fear response to a particular conditioned stimulus (CS) intensity, an increase or decrease in the CS intensity would result in changes in the fear response (Experiment 1); b) test Hull's (1943) theory that, in second-order conditioning, the second-order CS becomes associated with the response evoked by the first-order CS (Experiment 2); and c) attempt to replicate Rizely and Rescorla's (1972) finding that, following second-order conditioning, a second-order CS continues to evoke a conditioned response even after the conditioned response to the first-order CS has been extinguished (Experiment 3)