The role of visual experience in the emergence of cross-modal correspondences.

Cross-modal correspondences describe the widespread tendency for attributes in one sensory modality to be consistently matched to those in another modality. For example, high pitched sounds tend to be matched to spiky shapes, small sizes, and high elevations. However, the extent to which these correspondences depend on sensory experience (e.g. regularities in the perceived environment) remains controversial. Two recent studies involving blind participants have argued that visual experience is necessary for the emergence of correspondences, wherein such correspondences were present (although attenuated) in late blind individuals but absent in the early blind. Here, using a similar approach and a large sample of early and late blind participants (N = 59) and sighted controls (N = 63), we challenge this view. Examining five auditory-tactile correspondences, we show that only one requires visual experience to emerge (pitch-shape), two are independent of visual experience (pitch-size, pitch-weight), and two appear to emerge in response to blindness (pitch-texture, pitch-softness). These effects tended to be more pronounced in the early blind than late blind group, and the duration of vision loss among the late blind did not mediate the strength of these correspondences. Our results suggest that altered sensory input can affect cross-modal correspondences in a more complex manner than previously thought and cannot solely be explained by a reduction in visually-mediated environmental correlations. We propose roles of visual calibration, neuroplasticity and structurally-innate associations in accounting for our findings.