Abstract
Reward-associated but task-irrelevant information can interfere with our ability to focus on goal-relevant stimuli. In previous studies using a rewarded-Stroop task, font color naming responses were slower when the meaning of the color word matched the reward-associated color but the font color was a nonrewarded color (e.g., the word RED in blue font when red was a potential reward color and blue was not). This impairment has been referred to as the modulation of interference by reward associations (MIRA). It was proposed that MIRA occurs due to the transfer of reward association to the task-irrelevant dimension which then impacts attention. In this study, we associated one of four colors with a large reward and another with a small reward to determine whether the larger reward association would lead to greater MIRA when the word meaning was presented. Participants also completed a second block in which they completed the same task but fast and accurate responses to previously rewarded colors were no longer rewarded. Overall, responses were faster and more accurate when the font color signaled a large versus small reward, especially for a subsample of participants who were explicitly informed of the color-reward associations. However, MIRA was similar in the rewarded block for the small and large value-associated color word meanings, regardless of whether participants were informed or not. In the subsequent nonrewarded block, only the large value-associated word interfered with ink naming performance. The persistence of this behavioral response for highly rewarded colors coincides with previous findings in that reward-associated stimuli can influence behavior after reward is discontinued. These results suggest that the persistence of MIRA following the discontinuation of reward is dependent on the magnitude of the reward association but not awareness of the color-reward associations, and that larger reward associations might be more immune to extinction.