Abstract
Objectives. Previous studies found that auditory aftereffects were affected by accompanying visual stimuli (near the fovea), but not vice versa [Kitagawa & Ichihara, 2002]. We tested whether attending to an auditory signal affects the processing of a simultaneous peripheral visual stimulus. We also studied differences in performance with congruent and incongruent intermodal stimuli, and the effect of space-based attention.
Methods and Results. To quantify the visual processing, we tested the motion aftereffect (MAE) of an expanding disk. We used a double-staircase procedure to find the speed of expansion that annulled the MAE. In Experiment 1, during adaptation, we used co-located sounds that were either congruent (increasing intensity) or incongruent (decreasing intensity). Subjects had to perform an easy luminance-change discrimination task on the fixation mark, as well as an attentional task on the congruent and incongruent auditory stimuli. In a control condition, subjects had no auditory attentional task for the incongruent case. We found no effect of attention on MAE, and no differences between the congruent and incongruent conditions. In Experiment 2, during adaptation, we used short sound beeps that were not co-located with the visual stimulus, and subjects attended to the sound. In a control condition, there was no accompanying sound. The MAE was significantly reduced after attending to the sound, as compared to the no-sound control condition.
Conclusions. The results of Experiment 1 indicate that attending to co-located auditory stimuli cannot affect the processing of simultaneous visual stimuli. These results complement earlier findings by Duncan, Martens & Ward [1997] and Rees, Frith & Lavie [2001] for separate attentional resources for audition and vision. The results of Experiment 2 confirm that auditory-based spatial attention can affect the processing of simultaneously presented visual stimuli [e.g., Hikosaka, Miyauchi & Shimojo, 1996].