The Simon Effect With Saccadic Eye Movements.

In the Simon effect performance is faster and more accurate when the task-irrelevant spatial dimension of the stimulus corresponds to the location of the response, compared to when they do not correspond. In the prosaccade-antisaccade effect the latencies of saccades away from the stimulus location (i.e., antisaccades) are slower than the latencies of saccades toward the stimulus location (i.e., prosaccades). Because these two effects share a similar basis, the study of the Simon effect with saccadic eye movements needs to be decoupled from the prosaccade-antisaccade effect. A standard Simon task (Experiment 1) and a Simon task in which a distractor stimulus was also presented (Experiment 2) were implemented. In Experiment 1, results showed an effect likely attributable to the sum of the Simon effect and the prosaccade-antisaccade effect. In Experiment 2, in which the difference between the prosaccade and antisaccade was eliminated, only a Simon effect, cognitive in nature, manifested itself.