title: Investigating the in-between: multisensory integration of auditory and visual motion streams.
abstract: We investigated audiovisual interactions in motion perception by behavioral experiments testing both, the influence of visual stimuli on auditory apparent motion and the influence of auditory stimuli on visual apparent motion perception. A set of loudspeakers with an LED mounted in  the middle of each speaker cone was arranged in a semicircle. Apparent motion streams were presented for each modality alone in the unimodal conditions. In the bimodal conditions, stimuli of the second modality were added to fill the temporal and spatial gaps of the sampled trajectory of the  reference stream. The participants' task was to observe the quasi-naturalistic stimulus sequences and to perform a standard classification. The addition of stimuli of the second modality indeed facilitated apparent motion perception. Bimodal presentation increased the upper temporal interval  up to which the stimuli could be separated in time while still being perceived as continuous motion. We interpret these results as evidence for an ecologically advantageous audiovisual motion integration mechanism which operates beyond the constraints of strict spatiotemporal coincidence.  Functional considerations suggest that this mechanism may represent an amodal stage suited for the processing of both unimodal and bimodal signals.
authors.affiliation: Bremen University, Hochschulring 18, Bremen, Germany. tox@uni-bremen.de
authors.forename: Thorsten
authors.initials: T
authors.lastname: Kluss
authors.forename: Niclas
authors.initials: N
authors.lastname: Schult
authors.forename: Kerstin
authors.initials: K
authors.lastname: Schill
authors.forename: Manfred
authors.initials: M
authors.lastname: Fahle
authors.forename: Christoph
authors.initials: C
authors.lastname: Zetzsche
mesh_terms: D000328:Adult; D001307:Auditory Perception / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009039:Motion Perception / Q000502:physiology*; D011434:Proprioception / Q000502:physiology; D014796:Visual Perception / Q000502:physiology; D055815:Young Adult