Effects of ad libitum feeding and prefeeding on operant responding in sign- and goal-tracking rats

Abstract

Sign-tracking and goal-tracking are behavioral tendencies in which Pavlovian conditioned responses are directed either toward the cue for an unconditioned stimulus (sign-tracking) or toward the location of an unconditioned stimulus delivery (goal-tracking). The current study examined operant response rates in sign- (n = 7) and goal-tracking (n = 11) Wistar rats under a restricted feeding schedule, ad libitum access to food, and reinforcer devaluation by prefeeding either the same or a different flavored pellet reinforcer. Only goal-tracking subjects significantly decreased their response rates after reinforcer devaluation by prefeeding, and only when the flavor used in prefeeding matched the reinforcer flavor. Both groups of subjects decreased responding under ad libitum food access compared to a 16-h food restriction schedule, but this effect size was larger in goal-tracking rats. These results extend recent findings that sign-trackers are more likely than goal-trackers to continue conditioned responding after unconditioned stimulus devaluation during operant conditioning.