Synaesthesia

These are sensory perceptions experienced as accompanying sensations of another modality. The senses are transposed, stimulation appropriate to one sense organ being sensed by another, for example: different colours associated with musical notes or with words; or different tastes or smells, etc, associated with other senses. In some cases the stimulus for one sense elicits vivid perceptions in several senses. There are well-attested cases of people "seeing" with their fingers. This may be due to vestigial photosensitive cells on the skin surface or to nerve damage. Certainly, the connecting of a nerve fibre from the tongue to one from the ear to the brain allows taste to be sensed as noise.