THE EFFECT OF THE PROPORTION OF INCONGRUENT STIMULI ON STROOP CONGRUITY
In five experiments, the proportion of incongruent stimuli was varied from .25 to. 75, with touch screen responding. In all cases there was significant Stroop congruity. With proportions of incongruent stimuli of .50 or less, there was considerable congruity, more than 100 ms. With proportions of more than .50, congruity was considerably less, between 50 and 65 ms. The effect seems to be related to a strategy based on probability: If incongruent stimuli are more probable, ignore the word. If incongruent stimuli are equally probable or less probable, use the word if possible.