A Pavlovian, Conditioned-Reinforcement Approach to Reducing Impulsive Choice

Persistent impulsive choice (the preference for a smaller-sooner over a larger-later reward) is associated with consequential life outcomes. Procedures that reduce nonhuman impulsive choice have long training durations that may reduce their translational utility. The purpose of this experiment was to test a new behavioral intervention to reduce impulsivity that requires few sessions to implement. Delay-bridging stimuli (stimuli presented during the delay to a reward) have been shown to reduce impulsive choice, but delay-bridging stimuli may also be aversive. Conditioned stimuli (CS) established through Pavlovian training are, on the other hand, attractive, potentially even functioning as a conditioned reinforcer (CR). This experiment leveraged the attractive nature of a CS as a delay-bridging stimulus to decrease impulsive choice. Forty Long-Evans rats (20 male) were randomly assigned to undergo 8 sessions of Pavlovian training (lever-CS precedes food delivery), and the other half underwent Unpaired training (CS uncorrelated with food). During the test of impulsive choice that followed, choosing the LLR produced 10-s access to the lever- CS and 2 pellets 10-s after that. Pavlovian training increased self-control choice relative to rats in the Unpaired group. It is noteworthy that the duration of training (8 sessions) is less than most other learning-based interventions designed to reduce impulsive choice.