Why people gesture when they speak

It is shown that congenitally blind speakers gesture despite their lack of a visual model, even when they speak to a blind listener, because gestures require neither a model nor an observant partner.

Abstract

People use gestures when they talk, but is this behaviour learned from watching others move their hands when talking? Individuals who are blind from birth never see such gestures and so have no model for gesturing. But here we show that congenitally blind speakers gesture despite their lack of a visual model, even when they speak to a blind listener. Gestures therefore require neither a model nor an observant partner.