Task-Level Value Affects Trial-Level Reward Processing and Control

Abstract

AbstractDespite disagreement about how anterior cingulate cortex (ACC) supports decision making, a recent hypothesis suggests that activity in this region is best understood in the context of a task or series of tasks. One important task-level variable is average reward because it is both a known driver of effortful behaviour and an important determiner of the tasks in which we choose to engage. Here we asked how average task value affects reward-related ACC activity. To answer this question, we measured a reward-related signal said to be generated in ACC called the reward positivity (RewP) while participants gambled in three tasks of differing average value. The RewP was reduced in the high-value task, an effect that was not explainable by either reward magnitude or outcome expectancy. Average task value also affected cue-locked frontal midline theta (FMT), an ACC signal linked to cognitive control: FMT was enhanced for low-value cues relative to high-value cues. This effect was related to behaviour, as the more FMT a participant exhibited, the better they performed. These results suggest that ACC does not evaluate outcomes and cues in isolation, but in the context of the value of the current task.