Categorical tonality perception modulates crossmodal correspondences between musical chords and colors

We investigated the influence of categorical perception on crossmodal correspondence by examining whether the chord-color crossmodal mapping differs depending on the degree of categorical perception of musical chords within individuals rather than on their physical properties. The experiment used morphed chords of pure tones graded from minor to major. Participants, who were classified as either categorizers or non-categorizers using chord tonality identification and discrimination tasks, selected a color that they thought matched each chord. The results showed that only categorizers selected similar colors for within-category chord pairs and dissimilar colors for between-category chord pairs. The findings of this study suggest that in crossmodal correspondences, categorizers may organize the relationship between features in a sensory space, and this relationship is isomorphically projected onto the relationship of other associated sensory features.