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Michael Richards, Herbert Goltz, Agnes Wong; Audiovisual integration in amblyopia. Journal of Vision 2015;15(12):127. doi: https://doi.org/10.1167/15.12.127.
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© ARVO (1962-2015); The Authors (2016-present)
Introduction: Amblyopia is a developmental visual impairment resulting from abnormal visual experience in childhood. While it used to be thought of as a low-level sensory disorder, recent studies have shown higher-level perceptual deficits. This study will define the temporal and spatial characteristics of audiovisual sensory binding, and will employ the Ventriloquism Effect to determine the relative weighting of audition and vision in spatial localization in amblyopia compared to visually normal controls. Methods: Participants with amblyopia (n=4) and normal controls (n=12) judged simultaneity of acoustic and visual signals at 13 levels of onset asynchrony, and judged co-localization of acoustic and visual signals at 9 levels of horizontal spatial separation. Point of subjective equality and precision for unimodal (auditory or visual) and bimodal (audiovisual) spatial localization was determined using a 2-AFC task. Auditory stimuli were click trains with perceived position controlled by interaural level difference. Visual stimuli were Gaussian blobs flashed on a large LED screen. Spatial reliability of the visual signal was manipulated by changing the Gaussian blob size. All experiments were carried out in a dark acoustic chamber under binocular viewing conditions. Results: Participants with amblyopia perceived audiovisual simultaneity over a significantly broader range of signal onset asynchrony than normal controls, particularly when the visual signal occurred first. Unimodal and bimodal spatial localization precision was lower in participants with amblyopia than in controls at every Gaussian blob size. Both participant groups demonstrated superior spatial localization precision for bimodal stimuli than for either of the component unimodal stimuli. Conclusion: Participants with amblyopia appear to have diminished ability to detect audiovisual asynchrony and reduced precision in visual spatial localization, even when viewing binocularly. Similar to visually normal controls, however, they appear to integrate visual and auditory spatial signals to achieve a ‘bimodal advantage’ to enhance localization precision of bimodal stimuli.
Meeting abstract presented at VSS 2015
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