An examination of how reward associations facilitate and impair Stroop performance

Rewarded stimuli are prioritized by the attentional system. Behavioral performance is improved when the task-relevant dimension is tied to a potential reward but is impaired when the irrelevant dimension is reward related. Within the rewarded Stroop task, the facilitation (reward responsiveness) and impairment (modulation of interference of reward association; MIRA) from reward-associated stimuli are thought to be due to different cognitive processes. In four experiments, we explored whether reward responsiveness and MIRA were influenced by reward magnitude and persisted following reward discontinuation. We manipulated how informed participants were of the stimulus-reward contingency based on whether they received stimulus-reward color instructions and whether or not the stimulus-reward contingency was certain (i.e., one color was always tied to one reward outcome). Results suggest that greater reward magnitude increased reward responsiveness, especially when participants were informed about the stimulus-reward contingency. However, greater impairment (MIRA) by a large versus small reward related color word was only observed when participants had little knowledge of the reward contingency (i.e., no instructions and a more uncertain mapping of stimuli to rewards) or during the extinction phase when reward associated colors were less relevant. These findings highlight the distinction between reward responsiveness to maximize gains and the unintentional prioritization of related but irrelevant information and suggest that reward associations that elicit greater reward responsiveness do not necessarily lead to greater impairment of conflict processing.