S-R COMPATIBILITY EFFECTS DUE TO CONTEXT-DEPENDENT SPATIAL STIMULUS CODING

Responses are faster with spatial S-R correspondence than with noncorr espondence (spatial compatibility effect), even if stimulus location i s irrelevant (Simon effect). In two experiments, we sought to determin e whether stimuli located above and below a fixation point are coded a s left and right (and thus affect the selection of left and right resp onses) if the visual context suggests such a coding. So, stimuli appea red on the left or right eye of a face's image that was tilted by 90 d egrees to one side or the other (Experiment 1) or varied between uprig ht and 45 degrees or 90 degrees tilting (Experiment 2). Whether stimul us location was relevant (Experiment 1) or not (Experiment 2), respons es were faster with correspondence of (face-based) stimulus location a nd (egocentrically defined) response location, even if stimulus and re sponse locations varied on physically orthogonal dimensions. This sugg ests that object-based spatial stimulus codes are formed automatically and thus influence the speed of response selection.