Abstract
Prior research has shown that auditory pitch can influence spatial and motion estimates of visual stimuli. Cross-modal correspondence between pitch and space show high-pitched sounds are associated with upper space and low-pitched sounds with lower space (Evans & Treisman, 2010). Ambiguous motion stimuli are perceived as moving upward when paired with ascending pitch sounds and downward with descending pitch sounds (Maeda, Kanai, & Shimojo, 2004). However, the extent to which pitch sounds influence visual motion remains unclear. Also, how manipulating both a sound's pitch and location might influence visual motion perception has not been explored before. Therefore, we investigated how changes in pitch tones affect visual motion direction judgments while varying visual motion saliency and the pitch-spatial location relationship relative to the direction of a visual motion stimulus. Participants were presented with high or low pitch tones with a random dot kinematogram (RDK) stimulus displaying either upward or downward motion. Saliency of visual motion was manipulated by systematically varying the degree of coherent motion. In Experiment 1, the auditory stimuli were presented from two speakers placed left and right of the RDK display. In Experiment 2, the auditory stimuli were presented from either a speaker above or below the RDK display. Subjects had to judge the direction of the coherent motion dots by a 2AFC response. Experiment 1 showed subjects were more likely to judge the direction of visual motion as going up with high-pitched tones and down with low-pitched tones. In Experiment 2, we found an interaction of sound location and pitch (low-pitch tones from the bottom speaker yielded greater judgment bias than low-pitch tones from the top speaker). These findings show the extent to which pitch affects visual motion perception as the strength of the visual signal is varied and how this pitch effect is sensitive to the pitch-space correspondence.
Meeting abstract presented at VSS 2018