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Ayla Barutchu, Glyn Humphreys; Multisensory Enhancements with Unconscious Visual Stimuli in Posterior Cortical Atrophy. Journal of Vision 2016;16(12):138. doi: https://doi.org/10.1167/16.12.138.
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© ARVO (1962-2015); The Authors (2016-present)
Multisensory signals can enhance information processing even with task irrelevant sensory signals and cues, suggesting that some aspects of multisensory processing may be automatic. Nevertheless, the role of awareness in multisensory processing remains elusive. We aimed to investigate multisensory processing in a patient with posterior cortical atrophy (65 years at the time of testing) who presented with severe visuospatial problems and strong aspects of simultanagnosia. We also tested 12 age-matched controls using a simple audiovisual detection task. Participants responded to auditory, visual and semantically congruent and incongruent audiovisual presentations of a 'bird' and a 'dog' with varying stimulus onset asynchronies (SOAs): ranging between -300 - 300 ms. Healthy control participants responded to all signals with very high accuracy (M accuracy for all stimuli). Surprisingly, they also showed large multisensory gains for both congruent and incongruent presentations of multisensory stimuli in close temporal proximity (i.e., SOA less than 200 ms). The participant with PCA failed to respond to over of visual only stimuli, and the hit rate when visual signals were present did not differ from the false alarm rate when signals were absent. Nevertheless he showed multisensory enhancements in reaction time when the auditory signal was presented first, and, overall, the reliability of motor responses also improved. The data show for the first time that awareness of visual signals is not a pre-requisite for multisensory enhancements. Patients with severe visual perceptual deficits can benefit from multisensory signals even at an unconscious level. This finding broadens the possibility of new multisensory-based intervention strategies for patients with severe perceptual deficits.
Meeting abstract presented at VSS 2016
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