While changes in dACC activity have traditionally been associated with variability in decision difficulty, a recent high-profile study has suggested that dACC instead encodes the value of foraging. In this study, the authors challenge this previous finding by showing that, when foraging value and decision difficulty are effectively dissociated, dACC activity corresponds to changes in choice difficulty. Previous theories predict that human dorsal anterior cingulate (dACC) should respond to decision difficulty. An alternative theory has been recently advanced that proposes that dACC evolved to represent the value of 'non-default', foraging behavior, calling into question its role in choice difficulty. However, this new theory does not take into account that choosing whether or not to pursue foraging-like behavior can also be more difficult than simply resorting to a default. The results of two neuroimaging experiments show that dACC is only associated with foraging value when foraging value is confounded with choice difficulty; when the two are dissociated, dACC engagement is only explained by choice difficulty, and not the value of foraging. In addition to refuting this new theory, our studies help to formalize a fundamental connection between choice difficulty and foraging-like decisions, while also prescribing a solution for a common pitfall in studies of reward-based decision making.
Shenhav et al. (Sun,) studied this question.