Monday, October 24, 2011: 5:00 PM
Columbus Hall C-F (Hyatt Regency Chicago)
(BEC) Behavioral Economics

X.T. Wang, Ph.D.1, Shu Li, Ph.D.2 and Lilin Rao2, (1)University of South Dakota, Vermillion, SD, (2)Chinese Academy of Sciences, Beijing, China

Purpose: In two studies, we examined metabolic mechanisms of intertemporal choice within a synthetic framework of life-history theory and risk sensitive foraging theory. In a previous study (Wang & Dvorak, 2010) we identified a novel link between blood glucose (GB) levels and delay (future) discounting. People discount the future when they prefer a smaller and sooner (SS) reward to a larger but later (LL) reward when making intertemporal choices. We found that a sugar drink reduced delay discounting, making the LL options more attractive whereas a diet drink increased delay discounting, making the SS options more preferable. Based on these findings, we predict that when the body energy budget is low, the delay discounting rate would increase to get immediate supply, and vice versa.

Method: In Study 1, we examined the effects of varying BG levels on delay discounting in natural conditions measured by subjective ratings of hunger and actual temporal distance from the last meal. In Study 2, we checked the BG levels of the participants before making a hypothetical investment decision of allocating a certain amount of tax return for immediate use vs. short-term or/and long-term saving. We also examined the issue of resource allocation. The participants were asked to answer questions about contents and intension of a conversion between a man and a woman portrayed in a photo.

Result: The results from Study 1showed that the temporal distance but not subjective hunger perception was significantly and positively correlated with delay discounting. Results from Study 2 showed that the participants with higher BG levels were more likely to save the money for future use. The participants who were low in the BG levels were more likely to interpret the conversation in terms of sexual nature.

Conclusion: Fluctuating blood glucose levels continuously inform the brain about body energy budget, and allow the brain to regulate intertemporal choice adaptively by adjusting delay discounting rate and by making trade-offs between survival-related calorie intake and reproduction-related mating processes.