Abstract
Previous studies in adults suggest that auditory information can influence the detectability of visual information (for example, Stein et al., 1996; Lovelace et al., 2003; Oodgard et al., 2003; 3004). Little is known regarding the development of such influences. Here we investigate whether auditory cues can alter visual detectability in 3- and 6-month old infants. We used forced choice-preferential looking (FPL) to obtain contrast detection thresholds for a visual stimulus, a square (11x11[sup]0[/sup], centered 15[sup]0[/sup] left or right of monitor center. The visual stimulus fluctuated in luminance at 1 Hz, under four different auditory conditions: (1) IP: an auditory stimulus, white noise modulating in loudness at 1 Hz, fluctuated in-phase with the visual stimulus, (2) OP: the auditory stimulus fluctuated out-of-phase with the same visual stimulus, (3) NS: no auditory stimulus was presented, or (4) CS: a constant auditory stimulus was presented. The visual stimulus was presented at one of five contrasts, randomized across trials. Threshold was defined as the contrast yielding 75% correct performance in the FPL task. For each subject, visual thresholds were obtained for two of the four possible conditions, over the course of 2-3 days. If synchronized auditory information enhances visual detection, we expect lower contrast thresholds for the IP condition relative to the other conditions. Our data in 3- and 6-month-olds show that synchronized auditory information can worsen the detectability of visual stimuli near threshold. Such a counter-intuitive finding can be explained by the reallocation of cross-modal attention. If attention is a limited resource across modalities, a highly salient auditory stimulus can redirect attention away from a near-threshold visual stimulus, worsening visual detectability the most when visual and auditory information are changing in the same way over time (IP).
Meeting abstract presented at VSS 2013