Early blindness modulates haptic object recognition

Prior visual experience increases children's use of effective haptic exploration strategies in audio-tactile sound-shape correspondences

Sound-shape correspondence refers to the preferential mapping of information across the senses, such as associating a nonsense word like bouba with rounded abstract shapes and kiki with spiky abstract shapes. Here we focused on audio-tactile (AT) sound-shape correspondences between nonsense words and abstract shapes that are felt but not seen. Despite previous research indicating a role for visual experience in establishing AT associations, it remains unclear how visual experience facilitates AT correspondences. Here we investigated one hypothesis: seeing the abstract shapes improve haptic exploration by (a) increasing effective haptic strategies and/or (b) decreasing ineffective haptic strategies. We analyzed five haptic strategies in video-recordings of 6- to 8-year-old children obtained in a previous study. We found the dominant strategy used to explore shapes differed based on visual experience. Effective strategies, which provide information about shape, were dominant in participants with prior visual experience, whereas ineffective strategies, which do not provide information about shape, were dominant in participants without prior visual experience. With prior visual experience, poking-an effective and efficient strategy-was dominant, whereas without prior visual experience, uncategorizable and ineffective strategies were dominant. These findings suggest that prior visual experience of abstract shapes in 6- to 8-year-olds can increase the effectiveness and efficiency of haptic exploration, potentially explaining why prior visual experience can increase the strength of AT sound-shape correspondences.