Reducing impulsive choice: V. The role of timing in delay-exposure training.

Impulsive decision-making is common in addiction-related disorders, with some research suggesting it plays a causal role in their development. Therefore, reducing impulsive decision-making may prevent or reduce addiction-related behaviors. Recent research shows that prolonged experience with response-contingent delayed reward (delay exposure [DE] training) reduces impulsive choice in rats, but it is unclear what behavioral mechanisms underlie this effect. The present study evaluated whether improvements in interval timing mediate the effects of DE training on impulsive choice. Thirty-nine Long-Evans rats were randomly assigned to groups completing DE, immediacy-, or no-exposure training, followed by impulsive-choice and timing tasks (temporal bisection). Despite replicating the DE effect on impulsive choice, timing accuracy and precision were unaffected by DE training and unrelated to impulsive choice. The present findings did not replicate previous reports that timing precision and impulsive choice are related, which may be due to between-laboratory differences in impulsive choice tasks. Continued research to identify candidate behavioral mechanisms of DE training may assist in improving training efficacy and facilitating translational efforts.