Discounting of Food and Water in Rats Shows Trait- And State-Like Characteristics
Journal of the Experimental Analysis of Behavior
Wiley-Blackwell Publishing, Inc.
Delay discounting is the loss in value of an outcome as a function of its delay. The present study focused on examining a trait-like characteristic of delay discounting in a preclinical animal model. Specifically, we were interested in whether there was a positive relation between discounting of 2 different outcomes in rats. That is, would rats that discount delayed food steeply also discount delayed water steeply? In addition, we examined how session-to-session variability in discounting could be attributed to differences between subjects (trait variability) and to differences within subjects (state variability). Finally, we measured discounting from early- to mid-adulthood, allowing us to examine changes in discounting as a function of age. Overall, we found a moderate, positive correlation between discounting of food and discounting of water in rats, providing further evidence that the relative consistency with which individuals discount different outcomes is a trait-like characteristic. In addition, we found a high degree of within-subject variability in discounting, indicating strong state-like differences from session to session. Finally, overall, discounting decreased as a function of age; however, individual-subject data showed variability in how discounting changed across time. Overall, our results show that differences in delay discounting between individuals reflect variability in both trait- and state-like characteristics.
*Haynes, J. M., *Galizio,A., *Frye,C. C. J.,*Towse,C. C.,**Morrissey, K. N., Serang,S.,& Odum, A. L. (2021). Discounting of food and water in rats shows trait-and state-like characteristics. Journal of the Experimental Analysis of Behavior, 115(2), 495–509. https://doi.org/10.1002/jeab.677