Proceedings of the Annual Meeting of the Cognitive Science Society

The standard Stroop effect (which typically uses color words that form part of the response set) is robust and welldocumented in mean RT. Ex-Gaussian analyses reveal that this effect is seen in the mean of the normal distribution (mu),in the standard deviation of the normal distribution (sigma), and (c) in the tail (tau) of the ex-Gaussian distribution. Thepresent experiments investigate whether the semantically based Stroop effect (which contrasts incongruent color-associatedwords with neutral controls) is seen in the three ex-Gaussian parameters. This analysis yielded a semantic Stroop effect in thearithmetic mean and mu, but no semantic Stroop effect was observed in tau. These data are consistent with the conclusion thatinterference associated with response competition on incongruent trials is absent in the semantic Stroop effect (at least in thetail of the distribution).