Time and amount attributes exert distinct neural influences on gain and loss evaluation

Abstract People typically discount delayed gains more than delayed losses, reflecting a gain-loss asymmetry. This event-related potential study examined how neural representations of amount and time, two prominent attributes in delay discounting, are influenced by contextual valence (gains vs. losses) through the lens of neural dynamics. Forty participants performed a simple guessing task in which they experienced a gain context with varying reward amounts delivered at different time delays, and a loss context with varying loss amounts delivered similarly. Time and amount attributes were manipulated orthogonally and parametrically. Results showed that in the gain context, time attribute was first tracked during the reward positivity (RewP) period, then integrated with linearly-increasing monetary value during the P3 period, and finally processed independently from monetary value during the late positive potential (LPP) period. In the loss context, time was similarly processed during the RewP period, whereas monetary value was not tracked until the LPP period. Additionally, a correlation between behavioral and neural delay discounting was found in the loss but not gain context. Our findings demonstrate distinct evaluative processes for time and amount attributes between gain and loss contexts, providing new insights into the gain-loss asymmetry in delay discounting.