Neural dynamics of effort-modulated reward processing.

Previous studies have established that effort can either decrease reward value as a cost or increase reward value as an augmenter, which is referred to as the effort paradox. The present event-related potential study investigated the neural dynamics underlying the modulation of reward processing by effort expenditure. Thirty-two participants completed a modified monetary incentive delay task in a high-effort context and a low-effort context to earn monetary rewards while their EEG was recorded during effort anticipation, effort execution, and effort completion, respectively. Results revealed the multiphase nature of the effort-reward relationship, which unfolds over time. During effort anticipation, effort discounts reward value as reflected by a reduced contingent negative variation for high- versus low-effort trials. During effort exertion, the target-P3 reward effect was accrued by effort expenditure. Finally, effort also provides its own value following effort completion, as revealed by an enhanced stimulus-preceding negativity for high-effort relative to low-effort trials. These findings provide new insights into the relationship between effort expenditure and reward processing and are helpful to mitigate the effort paradox.