Kavli Affiliate: Vikram Chib
| Authors: Aram Kim and Vikram S. Chib
| Summary:
Decisions to exert effort for reward are often conceptualized as reflecting a trade-off between anticipated benefits and effort costs. However, economic theories propose that valuation is reference-dependent, such that behavior is shaped relative to expected outcomes rather than absolute reward magnitude. Whether reward expectations influence effort expenditure through such reference-dependent mechanisms, and how these computations are represented in the brain, remains unclear. Using an incentivized grip-force task during functional magnetic resonance imaging, we experimentally manipulated reward expectations independently of reward outcomes. Behavioral results showed that effort exertion varied systematically with reward expectations, indicating that individuals evaluated exertion relative to a reference point. Neural activity in the ventral striatum tracked both prospective reward expectations and deviations between expected and realized earnings. Moreover, these neural signals predicted individual differences in reference-dependent modulation of effort. Together, these findings identify ventral striatal representations associated with reference-dependent effort valuation and suggest that reference-dependent computations contribute to motivated behavior.