LEARYING AND hIOTIVATION ( 1974) 5, 209-220 Conditioned-Aversive Aspects of Electric Shock1 CHARLES R. CROWELL Unioersity of Iowa Two experiments were reported in which it was observed that a weak shock became more aversive as a result of appropriate pairing of that stimu- lus with a stronger shock. The enhanced aversiveness of the weak shock was reflected in Experiment 1 by an apparent increase in the reinforcement provided by response-contingent termination of that shock. In Experi- ment 2, the weak shock was observed to be more suppressive of a consum- matory-response baseline following appropriate pairings of the weak and strong shocks. The results of these studies were discussed in terms of their implications for certain aversive-conditioning situations in which shocks may serve, in part, as conditioned stimuli. That strong stimuli can produce a variety of unconditioned reactions ranging from what has been called “drive-arousing” or “motivational” to reflexive seems to be a well established fact. It is also possible, how- ever, that these “unconditioned stimuli” can acquire through learning the capacity to elicit various conditioned responses some of which may qualify as learned sources of drive. Mowrer ( 1960), for example, sug- gested that the motivational value of a primary aversive stimulus would be enhanced if its sensory consequences acquired secondary drive- arousing properties (pp. 130-131). Mowrer viewed the results of one of his earlier studies (Mowrer, 1940) as supportive of this conjecture. In this experiment escape conditioning was conducted with a shock of gradually mounting intensity. It was noted that the escape response tended over trials to occur earlier and earlier on the increasing shock intensity function. In addition, subjects apparently “detected” the shock earlier with successive training. These results suggest that weak-shock *The preparation of this article was supported in part by Grant MH 11734-05 from the National Institutes of Health to Dr. Judson S. Brown. The experiments reported herein were described in the thesis submitted by the author in partial fulfillment of the requirement of the Master’s degree at the University of Iowa. The ideas, guidance, and support provided by Judson S. Brown were indispensible to this project. The author also expresses thanks to Michael Suelzer for assistance with Experiment 1, and to Drs. 1. Gormezano and Donald J. Levis for a constructive evaluation of an earlier form of this manuscript. Requests for reprints should be sent to the author at the Department of Psychology, McMaster University, Hamilton, Ontario, Canada. 209 Copyright @ 1974 by Academic Press, Inc. All rights of reproduction in any form reserved.