The Meanings of Synesthetic Metaphors Closely Align With Crossmodal Correspondences

Synesthetic metaphors are expressions in which the meaning of a word is transferred from one sense to another (e.g., a bright sound). They have often been discussed in relation to crossmodal correspondences, psychological phenomena where systematic associations are perceived between different senses (e.g., brightness and pitch). However, the relationship between these two phenomena has largely been treated as an assumption, with limited empirical examination. The present study investigated the extent to which synesthetic metaphors and crossmodal correspondences are related to each other. Specifically, through experiments using the semantic differential technique, it examined whether, for example, the sound represented by a sweet sound corresponds to the sound crossmodally associated with a sweet taste. It was found that the meanings of synesthetic metaphors were generally consistent with crossmodal correspondences; however, those of synesthetic metaphors that were acceptable or conventional (e.g., a sour smell) diverged from crossmodal correspondences (e.g., a smell associated with a sour taste). Furthermore, they were found to agree more closely with crossmodal correspondences on emotionally loaded scales, such as bad-good and dirty-clean, than on relatively emotion-neutral scales, such as low-pitched-high-pitched. These findings indicate that the meanings of synesthetic metaphors, which generally align closely with crossmodal correspondences, may diverge from them when conventionalized and suggest that the two phenomena are emotionally mediated.