Abstract
Introduction: Constructing an internal representation of the external world involves continuous integration of multiple sensory streams. In the audiovisual realm, sensory signals with high temporal correspondence are likely to be bound into a single perceptual event. The range of signal onset asynchrony (SOA) over which paired audiovisual stimuli are perceived as simultaneous is known as the audiovisual temporal binding window, and normally narrows from childhood to adolescence. Amblyopia is a developmental visual impairment that is increasingly recognized to involve deficits in audiovisual integration, even when viewing with the fellow eye. We characterized the audiovisual temporal binding window in adults with unilateral amblyopia to further our understanding of the impact of developmental sensory disturbance on multisensory perception. Methods: All experiments were conducted in a dark acoustic chamber. Visual stimuli were presented on an LED screen, and auditory stimuli were presented via stereo speakers. Each trial consisted of a brief flash (32 ms) accompanied by an auditory click of equal duration. The SOA between the flash and click varied from 0 ms to 450 ms for both visual-lead and auditory-lead conditions. Participants with unilateral amblyopia (n = 12) and normal control participants (n = 22) judged simultaneity in a 2-AFC task under binocular conditions. A subset was tested under monocular conditions. Results: Adults with unilateral amblyopia had a broadened audiovisual temporal binding window compared to control participants in both the visual-lead and auditory-lead conditions (p < 0.01). There was no effect of viewing eye among participants tested monocularly. Conclusions: The temporal binding window is broadened in adults with unilateral amblyopia under both binocular and monocular viewing conditions. The associated audiovisual temporal binding window is similar to that observed in normal children, suggesting that unilateral amblyopia disrupts the normal process of developmental tuning.
Meeting abstract presented at VSS 2016