Extension of the Interstimulus Interval in Saccharin Avoidance Conditioning

Abstract

Thirty-eight male Sprague-Dawley rats were used in an investigation of the effect of interstimulus intervals of 0, 35, and 60 min. on the intensity and duration of the saccharin avoidance response with x-irra-diation as the unconditioned stimulus. A conditioned stimulus (0.1% sodium saccharin solution) presentation period of 10 min. resulted in trace intervals of 0, 25, and 50 between the cessation of the conditioned stimulus and the onset of x-irradiation. The subjects were exposed to whole body x-irradiation at a dose rate of 10.2 r/min. for a summated air exposure dose of 81.6 r. The 3 irradiated interstimulus interval groups were significantly different from a sham-irradiated control group but did not differ from each other in intensity and duration of the post-treatment saccharin avoidance response over 7 days. It was concluded that, under the conditions of this study, the saccharin avoidance behavior could not be considered as an entirely conditioned or learned phenomenon based upon the association of the conditioned and unconditioned stimuli, and that other factors must be responsible.