Analysis of response time distributions: an example using the stroop task

The shape of a response time (RT) distribution can be described by a 3-parameter model consisting of the convolution of the normal and exponential distributions, the ex-Gaussian. Analyses based on mean RT do not take the distribution's shape into account and, for that reason may obscure aspects of performance. To illustrate the point, the ex-Gaussian mode) was applied to data obtained, from a Stroop task. Mean RT revealed strong interference but no facilitation, whereas the analysis based on the ex-Gaussian model showed bath interference and facilitation. In short, analyses that do not take the shape of RT distributions into account can mislead and, therefore, should be avoided.