There is growing evidence that unpredictability and uncertainty can alter reward system functioning. The present study examined the impact of (1) a task-irrelevant unpredictable relative to predictable context and (2) individual differences in intolerance of uncertainty (IU) on the reward-related positivity (RewP), an event-related potential (ERP) response to monetary gains relative to losses. Specifically, 64 participants listened to predictable and unpredictable tone sequences while electroencephalography was recorded during a monetary gambling task. Participants also completed the Intolerance of Uncertainty Scale, which measures both cognitive distress (prospective IU) and behavioral inhibition (inhibitory IU) elicited by uncertainty, in addition to the Depression Anxiety Stress Scale-21 and Penn State Worry Questionnaire. Results indicated that the RewP was reduced during the unpredictable relative to the predictable context. Greater self-reported anxiety elicited by the unpredictable context was associated with a decreased RewP, and a decreased RewP was associated with poorer lose-shift behavioral adjustment. Furthermore, the RewP mediated the relationship between self-reported anxiety elicited by the unpredictable context and lose-shift behavioral adjustment. The IU subscales demonstrated the opposite relationship with the RewP across both contexts-inhibitory IU was associated with an attenuated RewP and prospective IU was associated with an enhanced RewP. In contrast, anxiety, depression, stress, and worry symptomatology were not associated with the RewP. This is the first study to demonstrate that an unpredictable context and individual differences in the degree to which people cannot tolerate uncertainty impact an ERP measure of reward system functioning.
Keywords: Event-related potentials; Intolerance of uncertainty; Reward; Unpredictability.