"The more you gestured, the less I gesture": Co-speech gestures as a measure of mental model quality.

Studies in the literature have revealed that a speaker’s co-speech gestures favor the construction of a complete and articulated mental model of the discourse by the listener; moreover, from the literature on co-speech gestures we know that they help the speaker to organize the stream of thought. Given these data, we hypothesized that a person who listens to a discourse accompanied by gestures would produce fewer co-speech gestures in recollecting the discourse compared to a person who listens to a discourse not accompanied by gestures. The analysis of the co-speech gestures produced by the participants in two experiments while recollecting the content of a discourse confirmed our predictions.