The effects of irrelevant stimuli: 1. The time course of stimulus-stimulusand stimulus-response consistency effects with Stroop-like stimuli, Simon-like tasks, and their factorial combinations

The effects of Simon- and Stroop-like stimuli are examined in isolation and in factorial combinations with different delays between the presentation o f the irrelevant and the relevant stimuli. The effects of irrelevant stimul i have different time courses depending on whether they overlap with the re levant stimulus (stimulus-stimulus overlap, Dimensional Overlap [DO] Type 4 ) or with the response (stimulus-response overlap, DO type 3). A new, compu tational, parallel distributed processing (PDP)-type model, DO'97, is prese nted that is based on the original DO model (S. Kornblum, 1994; S. Kornblum , T. Hasbroucq, Br A. Osman, 1990), and it postulates a nonmonotone irrelev ant stimulus activation function in addition to 2 temporally ordered, seria l, nonindependent stages: a stimulus processing stage and a response produc tion stage. DO'97 is able to simulate the temporal dynamic characteristics of the processes, with good fits to the empirical data. of this study and o ther published studies, at the level of means, variances, and distributiona l plots.