Construct Validity of the Stroop Color-Word Test: Influence of Speed of Visual Search, Verbal Fluency, Working Memory, Cognitive Flexibility, and Conflict Monitoring

Abstract Objective 85 years after the description of the Stroop interference effect, there is still a lack of consensus regarding the cognitive constructs underlying scores from standardized versions of the test. The present work aimed to clarify the cognitive mechanisms underlying direct (word-reading, color-naming, and color-word) and derived scores (interference, difference, ratio, and relative scores) from Golden’s standardized version of the test. Method After a comprehensive review of the literature, five cognitive processes were selected for analysis: speed of visual search, phonemic verbal fluency, working memory, cognitive flexibility, and conflict monitoring. These constructs were operationalized by scoring five cognitive tasks (WAIS-IV Digit Symbol, phonemic verbal fluency [letter A], WAIS-IV Digit Span, TMT B-A, and reaction times to the incongruent condition of a computerized Stroop task, respectively). About 83 healthy individuals (mean age = 25.2 years) participated in the study. Correlation and regression analyses were used to clarify the contribution of the five cognitive processes on the prediction of Stroop scores. Results Data analyses revealed that Stroop word-reading reflected speed of visual search. Stroop color-naming reflected working memory and speed of visual search. Stroop color-word reflected working memory, conflict monitoring, and speed of visual search. Whereas the interference score was predicted by both conflict monitoring and working memory, the ratio score (color-word divided by color-naming) was predicted by conflict monitoring alone. Conclusion The present results will help neuropsychologists to interpret altered patient scores in terms of a failure of the cognitive mechanisms detailed here, benefitting from the solid background of preceding experimental work.