A functional model to localize the conflict underlying the stroop phenomenon

A new functional response competition model to describe the cognitive processes underlying the Stroop phenomenon is proposed. The main challenge for any explanation is the asymmetry of the conflict, i.e. the fact that the meaning of the color word disturbs naming the color of an incongruent color-word-color stimulus far more than the irrelevant color disturbs reading the word. The model proposes that the organism processes both competing verbal responses by priming the relevant set and inhibiting the irrelevant set if both responses belong to different sets, and by computing internal delay-time differences if both responses belong to the same set. The model explains most of the existing data about the Stroop phenomenon and is in full accordance with present knowledge on selective attention, stimulus encoding, response selection, and psychological refractory period. It is confirmed by data of a Stroop experiment using a set of verbal color responses disjoint from the set of the stimulus color words. This experiment is based on the strategy often used in Stroop research to try to obtain a reversed Stroop effect in order to find an explanation of the Stroop effect. The data show full symmetry of competition, that is a Stroop effect and a reversed Stroop effect of about the same amount of increased reaction time.