Biases and regularities of grapheme-colour associations in Japanese nonsynaesthetic population.
Synaesthesia has been described as a perceptual phenomenon that creates a 'merging of senses'. Therefore, academic treatments have focused primarily on its sensory characteristics and similarities with veridical perception. This approach has dominated, despite parallel work that has suggested conceptual influences are involved, including data that show a large number of synaesthetic variants are triggered by linguistic symbols (e.g. words). These variants are the focus of a novel subfield that applies psycholinguistic methodology to the study of linguistic synaesthesias. This approach is redefining notions of synaesthesia and of the interplay between perceptual and non-perceptual systems, in addition to informing general theories of language. This review examines the emergent field of linguistic synaesthesia research and the broad range of linguistic mechanisms that are implicated.