Rats trained to escape shock by traversing a start box and 4-ft. runway were punished by equivalent fixed-distance or fixed-duration shocks during extinction. The two types of punishment did not significantly differ in their effects; both facilitated performance relative to a nonpunished control condition. A second experiment showed the basic self-punitive effect with avoi'dance-trained rats on a 50% (fixed-duration) punishment schedule. Speed increased progressively over trials; this increase in speed occurred in the punishment section of the alley and appeared on nonpunished as well as punished trials. These results relegate the reduction of punishment duration to a minor explanatory role and are supportive of a modified conditioned fear interpretation.

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Rats were given a series of fear-conditioning trials followed by avoidance training and punishment extinction. During fear conditioning, four groups (CS-100, CS-33, CS-0, CS-SK) were exposed to contiguous buzzer-shock pairings; for the fifth group (RB), buzzer and shock were paired randomly in time; and the sixth group (NB) received only shock. During extinction, CS-100, RB, and NB received continuous buzzer punishment; CS-33, partial buzzer punishment; CS-SK, continuous shock punishment; and CS-0, no punishment. Avoidance responding was facilitated by both partial and continuous secondary punishment, as well as primary punishment. Running speed and resistance to extinction were increasing functions of secondary punishment percentage. While substantial sensitization and novelty effects occurred, these were considerably weaker than the secondary punishment effect.1 Based on a doctoral dissertation submitted to the Department of Psychology of the University of Alabama. The author is indebted to Kenneth B. Melvin for his advice and criticism during the course of this research.

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