Electrophysiological correlates of decision making under varying levels of uncertainty.

When making decisions we are often faced with uncertainty about the potential outcomes of a choice. We therefore must rely upon a stimulus-response-outcome (S-R-O) rule learned from previous experiences of gains and losses. Here we report a study that used event-related potentials (ERP) to examine the neural and cognitive mechanisms involved in decision making when S-R-O rules are changing in a volatile manner. Thirty-one participants engaged in a reward-based decision-making task in which two contextual determinants of decision uncertainty were independently manipulated: Volatility (i.e. the frequency of changes in the S-R-O rules) and Feedback validity (i.e. the extent to which an S-R-O rule accurately predicts outcomes). Results of stimulus-locked ERPs showed that volatility of S-R-O rules was associated with two well-known neural signatures of cognitive control processes. First, increased S-R-O volatility in a high FV context was associated with frontally-based N2 (200-350ms) and N400 (350-500ms) components. Second, in a low FV context, volatility was associated with an enhanced late positive complex (LPC, 500-800ms) largest on frontal sites. Feedback-locked ERPs showed an enhanced Feedback-Related Negativity (FRN) and P300 for losses compared to wins as well as a volatility driven FRN. These results suggest that, in a high FV context, coping with volatility might involve conflict monitoring processes. However, in a low FV context, coping with frequent changes in the S-R-O rule might require greater attentional and working memory (WM) resources.