Peirce separated signs into symbols, icons, and indices. Clark and Gerrig placed these three modes into dialogue and proposed that one can describe (using words in their arbitrary conventional meanings), demonstrate (using actions that resemble their meaning), or indicate (e.g., pointing) to another person. Demonstrations include hand gestures, facial displays, direct quotations, and figurative language or metaphors.

In the article below and in our ongoing work, we have found that dialogue favours the use of all four kinds of demonstrations, while monologue suppresses it. That is, the rates of hand gestures, facial displays, direct quotations, and metaphors are all significantly lower in a pure monologue than in dialogues. Our current focus is on understanding how, when, and why this “dialogue effect” occurs.

*Bavelas, J. B., Gerwing, J., Sutton, C., & Prevost, D. (2008). Gesturing on the telephone: Independent effects of dialogue and visibility.