Electrophysiological correlates of affective context and risk-taking in human decision-making

Decision-making forms an integral part of everyday human life. Yet, understanding the processes that govern it has proven to be a difficult challenge. Historically, economists have suggested that individuals behave in a rational manner, choosing outcomes based on their expected value (EV). However, a number of systematic violations of EV have indicated that this is an inadequate explanation of the complexities involved in decision-making. One important variable that is now known to influence decision-making is affect. However, it is unclear how affective contexts might modulate the neural processes involved in decision-making. The aim of this thesis was to examine the role of affective priors on the event-related potentials (ERPs) associated with risk-taking and feedback processing. Across four studies the probability of reward, the interval between affective priors and subsequent decision-making were manipulated and the EV associated with outcomes was controlled within a simple two-choice gambling task. It was found that transient negative affective priors elicited a rapid neural response differentiating between subsequent risk and safe choices, indexed by a stimulus-locked P1/N1 complex. This component may reflect an automatic orienting of attention to salient stimuli after a negative experience. It is speculated that it may index a general vigilance detection mechanism in the brain. The feedback-related negativity (FRN), a neural correlate of outcome processing, was found to distinguish between good and bad outcomes in positive, but not negative valenced contexts. Furthermore, it was observed that subjective evaluations of outcomes, driven by prior affective states, modulated the FRN in the same way as objective evaluations did. Overall, the thesis demonstrates that affective priors modulate the decision-making process. Specifically, the data suggest that transient affective priors may enhance attentional processes related to choice selection, and sustained negative affect may inhibit the processes involved in the discrimination between good and bad outcomes.