The effect of gesture on speech production and comprehension.

Hand gestures are ubiquitous in communication. However, there is considerable debate regarding the fundamental role that gesture plays in communication and, subsequently, regarding the value of gesture for telecommunications. Controversy exists regarding whether gesture has a primarily communicative function (enhancing listener comprehension) or a primarily noncommunicative function (enhancing speech production). Moreover, some have argued that gesture seems to enhance listener comprehension only because of the effect gesture has on speech production. The purpose of this study was to examine the extent to which gesture enhances listener comprehension and the extent to which the effect of gesture on listener comprehension is mediated by the effects of gesture on speech production. Results indicated that gesture enhanced both listener comprehension and speech production. When the effects of gesture on speech production were controlled, the relationship between gesture and listener comprehension was reduced but still remained significant. These results suggest that gesture aids the listener as well as the speaker and that gesture has a direct effect on listener comprehension, independent of the effects gesture has on speech production. Implications for understanding the value of gestural information in telecommunications are discussed. Potential applications of this research include the design of computer-mediated communication systems and displays in which the visibility of gestures may be beneficial.