Synesthesia is a condition in which the stimulation of one sense prompts a reaction in another sense. Luria, a neuropsychologist, diagnosed an especially strong form of synaesthesia (five-fold synesthesia) in a Russian mnemonist named Solomon Veniaminovich Shereshevsky. Reportedly, the stimulation of one sense resulted in a reaction in every other sense. For example, if Solomon heard a musical tone played he would immediately see a color, touch would trigger a taste sensation, and so on. (Luria, Aleksandr Romanovich. 1987. The mind of a mnemonist: a little book about a vast memory. Cambridge: Harvard University Press. pp. 31. ISBN0-674-57622-5)