Synaesthesia is a condition in which a stimulus in one sensory modality automatically triggers a perceptual experience in another sensory modality. For example, on hearing a sound, the person immediately sees a colour. This volume brings together what is known about this fascinating neurological condition. The above questions, and new issues arising from the recent wave of cognitive neuroscientific research into synaesthesia, are debated in a series of chapters by leading authorities in the field.