Publication Date


Document Type


First Advisor

McAllister, Dorothy E.||McAllister, Wallace R.

Degree Name

M.A. (Master of Arts)

Legacy Department

Department of Psychology


Conditioned response; Fear


In order to test the notion that the amount of fear conditioned to a discrete CS increases as the intertrial interval (ITI) is lengthened beyond 165 sec., eight groups of rats received 25 classical fear conditioning trials (CS-shock pairings) in one side of a two-compartment box. For four of the groups, the ITI during conditioning was 165 sec. whereas for the other four it was 360 sec. Presumably, this procedure would result in fear being conditioned to both the discrete CS and to the situational cues. Twenty-four hours later, two of the groups at each ITI were placed in the conditioning box for one hour in an effort to extinguish fear of the situational cues. The remaining groups were placed, for the same length of time, in a neutral box located in the experimental room. Following this treatment, all Ss were allowed to jump a hurdle, in the absence of shock, from the conditioning box to the adjacent box and escape from the fear-eliciting stimuli. During hurdle-jumping training, one group under each ITI and extinction combination had the CS presented in the conditioning box; the other group did not. Presumably the learning of the hurdle-jumping response is motivated by fear and reinforced by the reduction of fear following the response and can, therefore, be used as an index of the amount of fear conditioned. The results indicated that two sources of fear, that elicited by the CS and that elicited by the situational cues, combine to form the total aggregate of fear present in the situation. The data further showed that the extinction procedure used was effective in decreasing fear of the situational cues. The results did not, within the range evaluated, support the notion that as ITI is lengthened, the amount of fear conditioned to a discrete CS increases.


Includes bibliographical references.||Includes illustrations.


vii, 54 pages




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