| Description: |
We inhabit a world that offers a multitude of sensory cues that need to be disambiguated in order to perceive and interact with our surrounding environment. However, it is not clear how goal-directed actions reciprocally influence multisensory integration processes. The current dissertation examined how directing attention through visual gaze and to-be-reached locations influenced multisensory perception of visual and auditory cues. Participants performed pointing movements towards one of three potential targets, while looking above or beside that target. At the onset of the movement, multisensory stimuli (i.e., one or two flashes combined with one or two beeps) could be presented at the target of the reaching action, or in one of the non-target locations. Audiovisual perception was quantified by examining the influence of the auditory beeps on the number of perceived flashes (i.e., audio-visual illusion). It was hypothesized that looking at and/ or reaching to a target would modulate audiovisual perception. The results revealed audiovisual perception (specifically the fusion illusion, though not the fission illusion) was enhanced at the target relative to the non-target locations. Audiovisual integration associated with the fusion illusion was further reduced with increasing eccentricity of non-target locations. As well, when decoupling gaze locations from the target locations, audiovisual perception was additively driven by gaze and reaching locations. Moreover, this modulation of audiovisual perception at target vs. non-target locations was only observed in the presence, but not the absence, of a goal-directed movement. Overall, the results indicated that deploying attention by looking and reaching to a target location may enhance audiovisual perception at that location, emphasizing the critical importance of voluntary movements to the perception of our surrounding environment. The data also suggest that the fusion and fission illusions may arise from distinct integration mechanisms. ; Ph.D. |