When meaning doesn’t matter, but location does: the effect of stimulus-hand proximity on conflict processing in the auditory modality

Studies have shown that variations in stimulus-hand proximity alter conflict processing. Stimulus-response (S-R) conflict in visuo- and auditory Simon tasks increases when response hands are placed close (proximal) to the stimulus compared to when they are placed far (distal) from the stimulus. Conversely, a stimulus-stimulus (S-S) conflict in a classical visual Stroop paradigm was reduced in a proximal compared to a distal stimulus-hand condition. This suggests that stimulus-hand proximity may affect S-S and S-R conflict processing differently. However, it remains unclear whether a proximal stimulus-hand condition would also reduce the Stroop conflict in the auditory domain, where the task-irrelevant information requires pure semantic processing independent of the visual-spatial component of reading. The present study investigated the influence of stimulus-hand proximity on S-S and spatial S-R conflict processing in an auditory gender-categorization Stroop task (Experiments 1 and 2) and a Simon task (Experiment 3) by using the same stimulus materials in all experiments. The results consistently demonstrated that the auditory Stroop effect was unaffected by stimulus-hand proximity. This raises the question of the extent to which stimulus-hand proximity in previous demonstrations of reduced visual Stroop effects impacted semantic or rather visual-spatial processing. Finally, introducing a task-irrelevant spatial stimulus attribute and transforming the auditory Stroop task into an auditory Simon task increased interference in the proximal compared to the distal stimulus-hand condition. These findings suggest that response hands near visual and auditory stimuli seem to facilitate spatial feature processing.