Four Trials Is Not Enough: The Amount of Prior Audio-Visual Exposure Determines the Strength of Audio-Tactile Crossmodal Correspondence Early in Development.

Successfully navigating the world involves integrating sensory inputs and selecting appropriate motor actions. Yet, what information belongs together? In addition to spatial and temporal factors, correspondence across sensory features also matters. In the Bouba-Kiki (BK) effect, spiky shapes are associated with sounds like "kiki", and round shapes are associated with "bouba". Such associations exist between auditory and visual (AV) and auditory and tactile (AT) stimuli, where objects are only explored via touch. Visual experience influences AT associations, which are weak in early blind adults and in fully sighted 6- to 8-year-olds, who have a more naïve visual experience. It has been found that prior AV exposure in children enhances AT associations. Here, we consider how the amount of prior AV exposure strengthens AT associations. Sixty-one 6- to 8-year-olds completed four or eight AV trials, which involved seeing a round and spiky shape and indicating which shape best matched a sound. Then, children completed 16 AT trials: feeling a round and spiky shape. Shapes were hidden from view, and children had to indicate which of the two shapes best matched a sound. We found that eight, but not four, trials of enhanced AT associations. Our findings suggest that the amount, not just the type, of prior exposure is important in the development of audio-tactile associations.