A qualitative systematic review of individual differences in Stroop task performance among healthy adults

: The Stroop task has long been considered the optimal tool to estimate the efficiency of processes underlying individuals' abilities to suppress a distracting prepotent response, often assuming that performance in this task can be predictive of individuals' behavior in other contexts. The use of the Stroop task as a proxy for assessing individuals' inhibitory (and, more generally, executive) control in both clinical and non-clinical settings has been challenged based on the poor reliability of (individual-level) Stroop task performance measures, particularly the Stroop effect, which is calculated as a difference in performance between two conditions. In addition to these measurement concerns, several other critical issues have not been sufficiently examined, including why self-evaluation measures poorly correlate with the Stroop-task performance, the direction of the (possible) causal relationships between the Stroop-task performance and other behavioral measures, and possible differences between oral and manual versions of the task. To gather clues to these issues, we systematically screened studies (n = 1121) in all the domains in which the Stroop task has been used and reviewed those (n = 108) investigating which individual differences in healthy adults are predicted by performance in this task. Surprisingly, the pattern of results we found was considerably fragmented, with only a few studies employing sufficiently large sample sizes to test their hypotheses (n = 30). Nevertheless, we drew on the most straightforward findings to provide more specific advice for authors interested in using this task to investigate and assess executive functioning and higher-level cognitive processing, language, visual processing, personality and attitudinal traits, or substance use.