Abstract
Previous studies have shown that auditory information can facilitate visual processing by improving visual sensitivity (for example, Caclin, et al., 2011; Gleiss & Kayser, 2014, Lippert et al., 2007, McDonald et al.,2000; Strömer et al., 2009). We tested the role of auditory salience in modulating crossmodal influences on visual detectability. We used a two-alternative forced choice procedure to obtain visual detection thresholds. The visual stimulus, an 11x110 square, centered 150 left or right of monitor center, fluctuated in luminance at 1 Hz, under two auditory conditions: (1) a high salience auditory stimulus (60 dB): a white noise modulated in loudness at 1 Hz and fluctuated in-phase (IP) or out-of-phase (OP) with the visual stimulus or (2) a low salience auditory stimulus (35 dB): a white noise modulated in loudness at 1 Hz and fluctuated IP or OP with the visual stimulus. Visual stimuli were presented at one of five luminances, randomized across trials. Auditory stimuli were task-irrelevant, containing no lateralized spatial information. Observers indicated their judgment via an eye movement, first look within a region of interest left or right of center. For each observer, percent correct data across visual luminance were fit with a Weibull function to determine visual threshold (75% correct performance). We found improved visual thresholds in IP, relative to OP, for the low salience auditory stimulus. However, in the same observers, same paradigm, we found improved thresholds in OP, relative to IP, for the high salience auditory stimulus. The out-of-phase benefit reported here in adults replicates our results in 3-month-old infants run in a similar paradigm, using forced-choice preferential looking. Our new results extend this work and show that auditory salience can reverse the in-phase benefit we find in the same subjects, the effect expected of in-phase, synchronous crossmodal interactions.
Meeting abstract presented at VSS 2015