The Falling Tone That Rolls Down the Hill and Gets Slumped: Vertical Mapping of Lexical Tones with Motion and Valence.

While a growing body of research has identified the crossmodal correspondences between nonlinguistic pitch and vertical space, little is known about the non-arbitrariness of linguistic tones within the language domain. This study investigates the vertical mappings of Cantonese lexical tones (high rising vs. low falling) in two crossmodal domains: (1) spatial motions (upward vs. downward) and (2) emotional valence (positive vs. negative). Results showed that Cantonese speakers could reliably map tones based on pitch and motion trajectories (i.e., rising contour is upward, and falling contour is downward), but the vertical mapping between tones and valence (i.e., rising contour is positive, and falling contour is negative) was much weaker and modulated by vowels. In general, these findings suggest that lexical tones can be conceptualized and understood in the vertical dimension, even in the language where speakers do not talk about tones using spatially relevant terms. In addition, tonal iconicity, and sound symbolism in general, is differentiated according to the mechanisms in which they are grounded. Specifically, sound symbolism that relies on a direct structural parallel produces a more consistent mapping, whereas correspondence grounded in metaphorical mediation is more easily influenced by other linguistic factors. Thus, this research provides evidence for the sound symbolic nature of lexical tones, suggesting their conceptual mapping in tonal languages.