Evaluating individual differences in rewarded Stroop performance: reliability and associations with self-report measures

In three separate experiments, we examined the reliability of and relationships between self-report measures and behavioral response time measures of reward sensitivity. Using a rewarded-Stroop task we showed that reward-associated, but task-irrelevant, information interfered with task performance (MIRA) in all three experiments, but individual differences in MIRA were unreliable both within-session and over a period of approximately 4 weeks, providing clear evidence that it is not a good individual differences measure. In contrast, when the task-relevant information was rewarded, individual differences in performance benefits were remarkably reliable, even when examining performance one year later, and with a different version of a rewarded Stroop task. Despite the high reliability of the behavioral measure of reward responsiveness, behavioral reward responsiveness was not associated with self-reported reward responsiveness scores using validated questionnaires but was associated with greater self-reported self-control. Results are discussed in terms of what is actually being measured in the rewarded Stroop task.