Pavlovian cues and self-control choice: The role of unpaired training

Interventions seeking to reduce impulsive choice in nonhuman animals (i.e., preference for smaller sooner over larger later rewards [SSR vs. LLR]) often require long training durations. However, prior studies illustrate how a brief course of Pavlovian training can reduce rodents' impulsive choice by attracting them to the LLR and by providing an appetitive Pavlovian conditioned stimulus (CS) contingent on LLR choices. In these studies, the comparison group completed unpaired (UN) training where the CS and US never co-occurred. The present study added a truly random control (TRC) group to evaluate whether UN training made the CS aversive, exaggerating the effect of Pavlovian training on self-control. Following Pavlovian (PAV), UN, or TRC training, a lever CS was inserted into the chamber during half the delay to the LLR. PAV rats were significantly more attracted to the lever during training and chose the LLR significantly more often than TRC or UN rats. Significant sex differences were detected, with self-control influencing the effects of Pavlovian training predominantly observed in male rats. Because sex differences in self-control outcomes were not observed in the only other study to examine the effects of presenting an appetitive CS after LLR choices, possible reasons for this interexperiment difference are discussed.