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.