Task rule-congruency and Simon-like effects in switching between spatial tasks

In task switching, a response indicated as correct by both task rules is executed more quickly than one for which the rules disagree. This rule-congruency, so far demonstrated unequivocally only in nonspatial tasks, shows that the currently irrelevant task set is kept active. However, in spatial task-switching, rule-congruency could potentially reflect a preexperimental tendency that contributes to a Simon-like effect. In the present study, participants switched between RIGHT-LEFT and UP-DOWN tasks with either a standard key arrangement (e.g., upper key=UP) or a mapping-reversed arrangement (e.g., up = DOWN), which reverses the direction of the potential Simon-like effect but leaves potential rule-congruency effects unchanged. Mapping-reversal did not modulate any other effect, including rule-congruency, and therefore indicated rule-congruency unequivocally. Finally, implications concerning generality versus domain specificity of control processes in task switching are discussed.