Attentional resource allocation across vision and audition depends on stimulus attributes rather than task type

When we pay attention to two concurrent tasks, our performance is often deteriorated due to shortage of attentional resources. It has been controversial whether the attentional resources are shared by vision and audition, where continuous updating of attention can be an important factor. The present study investigated the effect of the continuous updating of attention on the interference between vision and audition. In Experiment 1, participants engaged in one-shot and continuous object-based attention tasks of luminance-change (vision) and pitch-change (audition) detection. The results showed better performance under the cross-modal condition, suggesting separate attentional resources for vision and audition at least partially. In Experiment 2, the second task was replaced with the vowel-detection task(visual or spoken) that is different from the first visual task (luminance change) but similar across modalities. The results showed no difference in interference by vision and audition, suggesting shared attentional resources for vision and audition. These result simply that the attributes of the stimuli used in the concurrent tasks is more important than continuous updating of attended information for attentional resource allocation across vision and audition.