Deploying attention to the target location of a pointing action modulates audiovisual processes at nontarget locations

The current study examined how the deployment of spatial attention at the onset of a pointing movement influenced audiovisual crossmodal interactions at the target of the pointing action and at nontarget locations. These interactions were quantified by measuring the susceptibility to the fission (i.e., reporting two visual flashes under one flash and two auditory beep pairings) and fusion (i.e., reporting one flash under two flashes and one beep pairing) audiovisual illusions. At movement onset, unimodal, or auditory and visual bimodal stimuli were either presented at the target of the pointing action or in an adjacent, nontarget location. In Experiment 1, perceptual accuracy within the unimodal and bimodal conditions was lower in the nontarget relative to the target condition. The fission illusion was uninfluenced by target condition. However, the fusion illusion was more likely to be reported at the target relative to the nontarget location. In Experiment 2, the stimuli from Experiment 1 were further presented at a location near where the eyes were fixated (i.e., congruent condition), where the hand was aiming (i.e., target), or in a location where neither the eyes were fixated nor the hand was aiming. The results yielded the greatest susceptibility to the fusion illusion when the visual location and movement end points were congruent relative to when either movement or fixation was incongruent. Although attention may facilitate the processing of unisensory and multisensory cues in general, attention might have the strongest influence on the audiovisual integration mechanisms that underlie the sound-induced fusion illusion.