This study aimed to compare the behavioural and neural correlates of delay discounting for primary (food) and secondary (money) rewards in normal-weight individuals. To this end, 28 participants were asked to make several decisions between a smaller amount of food/money to be received immediately vs. a larger amount of food/money to be received at a later timepoint while their brain was imaged using fMRI.
The study revealed that while participants exhibited similar discounting behaviour for both money and food rewards, they displayed steeper discounting i.e., higher impulsivity, in decisions related to food rewards. These results suggest a general preference for immediate gratification across reward types and a stronger inclination towards instant gratification especially for primary rewards. fMRI data also revealed differences in brain activity associated with monetary and food discounting. While money discounting was associated with higher activity in regions involved in executive control (dorsolateral prefrontal cortex), reward processing (dorsal striatum), and memory encoding/retrieval (hippocampus), food discounting was associated with a higher activity in a region (temporoparietal junction) involved among other in social reinforcement and social perspective taking.
These insights not only further the understanding of value-based decisions but could inform strategies and approaches aiming to address impulsive decision-making, seen commonly in individuals with addictive behaviour.