Extension of the Interstimulus Interval in Saccharin Avoidance Conditioning

Thirty-eight male Sprague-Dawley rats were used as subjects in an investigation of the effect of three durations of interstimulus interval on the saccharin avoidance response with x-irradiation as the unconiditioned stimulus (UCS). Interstimulus intervals of 10, 35, and 60 minutes with a conditioned stimulus (CS) period (saccharin solution presentation) of 10 minutes produced no differential effect in intensity and duration of the avoidance response over seven posttreatment days in subjects exposed to summated air exposure doses of 81.6 r at a dose rate of 10.2 r/min. The three irradiated interstimulus groups were significantly different in avoidance behavior from the sham-irradiated control group. A trend analysis of the saccharin index scores showed a significant positive extinction trend in all irradiated groups. It was concluded that under the conditions of this experiment the degree of avoidance behavior evidenced by the subjects in this study could not be attributed entirely to learning or to the conditioning process, and that radiation as a motivating stimulus has unique properties which differ from other nociceptive stimuli used in conditioning avoidance behavior. (auth)