Abstract
In everyday life, localising a sound source is often necessary for our survival. It is now well known that when visual localisation is good and informative, vision dominates and captures sound (e.g. Alais and Burr, 2004). What is still unclear is whether an uninformative visual signal can bias sound localisation. Optimal use of sensory signals for localisation predicts that an uninformative signal should be ignored. To test this we used an apparatus including 9 speakers positioned at the right side of a computer screen in a semicircle and asked participants to judge which one of two beeps (a standard and a comparison) was closer to the monitor in either a noiseless environment or one with added auditory noise. The comparison beep could be presented either with or without a synchronous flash positioned at the centre of the screen, while the standard beep was always presented alone. We analysed the number of times that the comparison stimulus was perceived as closer to the monitor as a function of beeps’ spatial displacement. For adults, points of subjective equality (PSEs) shifted significantly when the flash was presented, showing that the flash pulled the perceived position of beeps towards the monitor. The addition of auditory noise slightly increased this effect. Preliminary results also indicate that 8-year-old children may be similarly influenced by the flash presentation, but only in the noiseless condition. In the noisy condition, in contrast, their performance is completely disrupted by the flash. These results indicate that uninformative visual information can affect sound localization, resulting in percepts that are not optimal for localising the sound. Auditory noise may differently affect audiovisual integration in 8-year-old children and adults, consistent with recent reports (Barutchu et al, 2010).
Meeting abstract presented at VSS 2012