The Stroop phenomenon: perceptual conflict or response competition?

The Stroop phenomenon has recently been explained by two contrasting approaches, the perceptual conflict and the response competition. This experiment was designed to evaluate the two different explanations. 24 undergraduates were tested on the three sets of Stroop stimuli while hearing their verbal responses under delayed auditory feedback and under normal feedback. Delayed feedback produced differential response decrements across Stroop conditions. The findings supported predictions of the response-competition hypothesis and disconfirmed those of the perceptual-conflict hypothesis.