Hungry and Impulsive: Does blood glucose predict impulsivity for future rewards in a fasted state?
Delay discounting measures the rate at which the present value of a reward is discounted, in relation to the delay in receiving the reward. Delay discount rates are often measured as an indicator of impulsivity and involve temporal reward preferences (e.g. would you prefer 10 now or 11 in a month?). Previous research suggests that commodities are discounted at different rates depending on how they are processed by the body (Charlton & Fantino, 2008). The current study aims to compare the delay discounting rates of individuals in normal and food deprived states, across three different commodities (money, food and music). Glucose levels and current subjective hunger cravings (FCQ-S) are measured to investigate potential predictors of delay discounting rates Delay discounting rates of each commodity are measured for 50 participants in a food deprived state and a control state, during two sessions 1-2 weeks apart (M= 9.24 days). Analysis shows that food is discounted at a higher rate in the food deprived condition. A carry-over effect was also witnessed in the fasted state, showing a generalised increase in discounting rates across all commodities. This suggests that people should exercise caution even when making non-food decisions when hungry due to increased valuation of sooner rewards. Results show that blood glucose concentration is unable to predict discount rates; instead findings point towards a subjective hunger construct.