Ordering cross-modal events in time: When illusory and veridical perceptions coexist
Poster Presentation

Salvador Soto-Faraco
ICREA & Parc Cientific de Barcelona, Universitat de Barcelona

Agnes Alsius
Dept. Psicologia Basica & Parc Cientific de Barcelona, , Universitat de Barcelona

     Abstract ID Number: 40
     Full text: Not available
     Last modified: March 13, 2006
     Presentation date: 06/18/2006 4:00 PM in Hamilton Building, Foyer
     (View Schedule)

Abstract
A prevalent view in multi-sensory integration literature is that cross-modal binding results in a coherent and unitary perceptual experience. This is used to explain the dramatic illusions that are often experienced as a consequence of exposure to inter-sensory conflict such as the McGurk illusion. Looking at lip movements that mismatch an acoustically presented syllable (i.e., the lip movements of [ga] with the sound /ba/) leads to an alteration of what is heard (often /da/, in the example). However, in stark contrast with the assumption of unity, here we report that observers can access veridical information regarding the true temporal order of unisensory component signals of an audiovisual syllable, while at the same time they experience an acoustic illusion that results in a reversal of the time order of the information specified in each sensory modality. This result raises the possibility that our brain can gain access to some unimodal component information as well as to the result of the integrated percept, suggesting the separability between the processing level at which sensory judgments can be made and the processing level at which multisensory binding occurs.