Sequential modulations of logical-recoding operations in the Simon task.

The Simon effect consists of faster responses to the color (or another nonspatial feature) of spatially corresponding stimuli than to spatially noncorresponding stimuli. Recently, several studies observed the Simon effect after corresponding predecessor trials, but not after noncorresponding predecessor trials. To explain these sequential modulations, Stürmer et al. (2002) proposed a mechanism modulating the ability of stimulus position to automatically activate a response. The present study investigated which events are effectively triggering this mechanism in a variant of the Simon task, in which both stimuli and responses varied in color (participants wore colored gloves) as well as in horizontal position. In the same-color task (e.g., green stimulus-green response), a normal Simon effect showed up after corresponding trials, but no effect occurred after noncorresponding trials. In the alternate-color task (e.g., green stimulus-red hand), no effect occurred after spatially corresponding trials, whereas an inverted Simon effect was found after noncorresponding trials. Additional analyses showed that repetition (or alternation) effects did not affect the results. The results are discussed in terms of a conflict-monitoring account (Stürmer et al., 2002), and in terms of a feature-integration account (Hommel et al., 2002).