Psychology, Department of


Date of this Version

March 1996


Published in Journal of Experimental Psychology: Animal Behavior Processes 22:1 (1996), pp. 87–104. Copyright ©1996 by the American Psychological Association, Inc. Used by permission. “This article may not exactly replicate the fi nal version published in the APA journal. It is not the copy of record.”


Four experiments using barpress conditioned suppression in rats found that tone evoked more freezing (immobility) than did light. Still, tone and light appeared to have similar conditioned value as assessed by suppression in Experiments 1, 2, and 3, and by blocking, second-order conditioning, and over-conditioning assays in Experiments 1, 2, and 3, respectively. Experiment 4 arranged for tone to evoke less suppression than light but more freezing. Results suggest that in fear conditioning, the nature of the conditioned stimulus affects the form of conditioned responding (strong vs. weak freezing). This conclusion extends one drawn by P. C. Holland (1977) on the basis of his work in appetitive conditioning.