Bidirectional dynamics of mood, reward, effort and exploration in naturalistic task environments

Despite the broad literature examining the causes and consequences of mood, the concept of mood remains to be ambiguous. Prior work suggests that reward, effort, and exploration each contribute to and are affect by mood, yet there is no comprehensive model of mood that synthesizes its relationship with these interacting elements of motivated behaviour. Here, across four samples of human participants (total N = 399) completing a virtual exploration task, we found that effort expenditure, exploration, and reward independently predicted momentary mood. Specifically, increased exploration predicted more positive mood irrespective of the reward outcome or effort demands. Importantly, effort appeared to have dual, opposing effects on mood: On one hand, increased effort expenditure predicted more negative mood, and on the other hand, reward predicted subsequent mood only when foraging required effort. Mood, in turn, was positively associated with subsequent exploration but not effort expenditure, suggesting that mood selectively influences exploratory tendencies. These findings advance our understanding of mood and shed light on the paradoxical nature of effort as having both value-enhancing and discounting effects.