Effects of CS amount on conditioned taste aversion at different CS-US intervals

Previous studies on the effect of CS amount/duration on the conditioning of taste aversion have reported that animals having greater contact with the CS acquire greater aversion. These findings appear to contradict studies of CS preexposure, which show that greater contact with the CS results in less aversion. In the present research, the effect of CS amount was shown to depend on the CS-US interval. Thus, a 10-ml CS (0.15% saccharin) at 3- and 9-h CS-US intervals produced less aversion than a 1-ml CS, but there was no significant effect of CS amount at a 30-min interval. These results suggest a two-process interpretation of the delay gradient in conditioned taste aversion: one process (learned safety) is dominant at relatively long CS-US intervals, and a different process becomes dominant at short intervals.