The feeling of "kiki": Comparing developmental changes in sound-shape correspondence for audio-visual and audio-tactile stimuli

Sound-shape crossmodal correspondence, the naturally occurring associations between abstract visual shapes and nonsense sounds, is one aspect of multisensory processing that strengthens across early childhood. Little is known regarding whether school-aged children exhibit other variants of sound-shape correspondences such as audio-tactile (AT) associations between tactile shapes and nonsense sounds. Based on previous research in blind individuals suggesting the role of visual experience in establishing sound-shape correspondence, we hypothesized that children would show weaker AT association than adults and that children's AT association would be enhanced with visual experience of the shapes. In Experiment 1, we showed that, when asked to match shapes explored haptically via touch to nonsense words, 6- to 8-year-olds exhibited inconsistent AT associations, whereas older children and adults exhibited the expected AT associations, despite robust audio-visual (AV) associations found across all age groups in a related study. In Experiment 2, we confirmed the role of visual experience in enhancing AT association; here, 6- to 8-year-olds could exhibit the expected AT association if first exposed to the AV condition, whereas adults showed the expected AT association irrespective of whether the AV condition was tested first or second. Our finding suggests that AT sound-shape correspondence is weak early in development relative to AV sound-shape correspondence, paralleling previous findings on the development of other types of multisensory associations. The potential role of visual experience in the development of sound-shape correspondences in other senses is discussed.