The effect of attentional loads on audiovisual integration: When spatial coincidence matters.

Although prior studies have stated that the cross-modal interaction between simple and arbitrarily paired audiovisual (AV) stimuli can also be observed even when a person is instructed to ignore a particular modality, this may indicate that cross-modal integration takes place automatically, regardless of attentional control. Nevertheless, it is not clear whether attentional resources are actually required for cross-modal interactions between simple and meaningless AV stimuli to occur when the subject is instructed to ignore the auditory modality and whether attentional loads would have different influences on the cross-modal interactions between simple AV stimuli presented at the same position or at different spatial positions. In the present study, we adopted a rapid serial visual presentation (RSVP) stream as the distractor task to manipulate different attentional loads: no attentional load, a low attentional load, and a high attentional load. Additionally, spatial coincidence was controlled by presenting visual and auditory stimuli at the same or different locations. The results revealed that spatially congruent auditory stimuli can provide a particularly effective means of improving the ability to identify visual targets even when they occur in high-load conditions, whereas spatially incongruent auditory stimuli cannot enhance the ability to identify visual targets under high-load conditions.