Iconicity in vocalization, comparisons with gesture, and implications for theories on the evolution of language

Scholars have often reasoned that vocalizations are extremely limited in their potential for iconic expression, especially in comparison to manual gestures (e.g., Armstrong & Wilcox, 2007; Tomasello, 2008). As evidence for an alternative view, we first review the growing body of research related to iconicity in vocalizations, including experimental work on sound symbolism, cross-linguistic studies documenting iconicity in the grammars and lexicons of languages, and experimental studies that examine iconicity in the production of speech and vocalizations. We then report an experiment in which participants created vocalizations to communicate 60 different meanings, including 30 antonymic pairs. The vocalizations were measured along several acoustic properties, and these properties were compared between antonyms. Participants were highly consistent in the kinds of sounds they produced for the majority of meanings, supporting the hypothesis that vocalization has considerable potential for iconicity. In light of these findings, we present a comparison between vocalization and manual gesture, and examine the detailed ways in which each modality can function in the iconic expression of particular kinds of meanings. We further discuss the role of iconic vocalizations and gesture in the evolution of language since our divergence from the great apes. In conclusion, we suggest that human communication is best understood as an ensemble of kinesis and vocalization, not just speech, in which expression in both modalities spans the range from arbitrary to iconic.