title: The ventriloquist in periphery: impact of eccentricity-related reliability on audio-visual localization.
abstract: The relative reliability of separate sensory estimates influences the way they are merged into a unified percept. We investigated how eccentricity-related changes in reliability of auditory and visual stimuli influence their integration across the entire frontal space. First, we surprisingly found that despite a strong decrease in auditory and visual unisensory localization abilities in periphery, the redundancy gain resulting from the congruent presentation of audio-visual targets was not affected by stimuli eccentricity. This result therefore contrasts with the common prediction that a reduction in sensory reliability necessarily induces an enhanced integrative gain. Second, we demonstrate that the visual capture of sounds observed with spatially incongruent audio-visual targets (ventriloquist effect) steadily decreases with eccentricity, paralleling a lowering of the relative reliability of unimodal visual over unimodal auditory stimuli in periphery. Moreover, at all eccentricities, the ventriloquist effect positively correlated with a weighted combination of the spatial resolution obtained in unisensory conditions. These findings support and extend the view that the localization of audio-visual stimuli relies on an optimal combination of auditory and visual information according to their respective spatial reliability. All together, these results evidence that the external spatial coordinates of multisensory events relative to an observer's body (e.g., eyes' or head's position) influence how this information is merged, and therefore determine the perceptual outcome.
authors.affiliation: Centre de Recherche en Neuropsychologie et Cognition (CERNEC), Département de Psychologie, Université de Montréal, Montréal, Canada.
authors.forename: Geneviève
authors.initials: G
authors.lastname: Charbonneau
authors.forename: Marie
authors.initials: M
authors.lastname: Véronneau
authors.forename: Colin
authors.initials: C
authors.lastname: Boudrias-Fournier
authors.forename: Franco
authors.initials: F
authors.lastname: Lepore
authors.forename: Olivier
authors.initials: O
authors.lastname: Collignon
mesh_terms: D000328:Adult; D001307:Auditory Perception / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009949:Orientation; D010775:Photic Stimulation / Q000379:methods; D011597:Psychomotor Performance / Q000502:physiology*; D015203:Reproducibility of Results; D013017:Sound Localization; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult
keywords: eccentricity; multisensory integration; reliability; spatial localization; ventriloquist effect