Multisensory enhancement of localization with synergetic visual-auditory cues

Enhanced behavioral performance mediated by multisensory stimuli has been shown using a variety of measures, including response times, orientation behavior and even simple stimulus detection. In the particular case of the study of saccadic response to unimodal or bimodal stimuli, Corneil et al. (2002) were able to show that the bimodal visual-auditory saccades benefited from the accuracy of visual saccades at saccadic response time (SRTs) typical of auditory saccades. However, there has been little evidence of multisensory mediated improvement in stimulus localization. Recently, Hairston et al. (2003) shows improvement in visual-auditory localization performance (variability) for induced myopia while no benefit was reported for normal vision. Using a similar experimental design, taking into account two space dimensions, azimuth vs. elevation, we examined the ability of human subjects to localize visual, auditory and combined visual-auditory targets for stimuli considered optimal for the given task. The results showed significant improvement in bimodal localization when compared with the more accurate modality, visual, as measured with multi criterion data (precision, dispersion and orientation of the response patterns). Furthermore, the 2D analysis of combined visualauditory target localization performance, for azimuth and elevation response components, underlines the role of the auditory system in the determination of the response characteristics. The data suggested that visual-auditory localization performance benefited from the “best of the two worlds” (Corneil et al., 2002), in that it was improved only in the horizontal plane, and restricted to the response criterion where audition is more reliable than vision.