What term describes a perceptual experience where stimulation of one sense produces unusual experiences in another?

The term that describes a perceptual experience where stimulation of one sense produces unusual experiences in another is synæsthesia. This phenomenon occurs when the stimulation of one sensory pathway leads to automatic, involuntary experiences in a second sensory pathway. For example, a person might associate certain sounds with specific colors or taste flavors when they see certain numbers. This blending of the senses can create rich and unique sensory experiences, making synæsthesia a fascinating subject in both literature and psychology.

In the context of the other options, synecdoche refers to a figure of speech where a part is used to represent the whole or vice versa, rather than a sensory crossover. Tautology involves the unnecessary repetition of the same idea in different words, which does not relate to sensory experience. Finally, theme pertains to the central topic or message of a literary work, which is distinct from the sensory experiences described by synæsthesia.