The Silent Grammar of Gesture

A For as long as people have spoken to one another, they have also moved their hands. Gesture is not an ornament added to language but a companion that appears wherever speech is found, in every documented society and at every age. Blind children, who have never seen anyone gesture, still move their hands as they talk, and speakers on the telephone gesture busily to listeners who cannot possibly see them. This stubborn universality has convinced many researchers that gesturing and speaking are not two separate skills but two branches of a single system, produced together by the same mind and unfolding in the very same moment. Cultures that prize complete stillness in a speaker are very much the exception, and even people who are convinced that they never gesture can be filmed moving their hands freely the instant they warm to a subject.

B The most common gestures are the small, rhythmic flicks of the hand that researchers call beats. Beats carry no picture and no dictionary meaning; instead they fall on the words a speaker wishes to stress, rising and dropping in time with the voice like the movements of a conductor keeping an orchestra together. Because they are bound so tightly to the music of speech, beats vanish the moment a person stops talking and return the instant they resume. Their task is not to describe the world but to mark its most important points, steering a listener's attention towards whatever the speaker judges to matter most.

C A very different class of gesture is the emblem, a movement with a fixed meaning that can stand on its own without any accompanying words. The thumbs-up, the beckoning finger and the ring made of thumb and forefinger are all emblems, and it is precisely because their meanings are agreed by a community rather than given by nature that they refuse to travel. A gesture that signals warm approval in one country may be a grave insult a few hundred kilometres away. Travellers who assume that their hands will be understood everywhere are frequently caught out, for emblems must be learned deliberately, exactly as the words of a foreign language are learned. Because emblems are agreed upon rather than natural, a community can coin new ones whenever it pleases, and a movement that is fashionable in one generation may look quaint or baffling to the next. It is for this reason that a dictionary of gestures, like an ordinary dictionary, has to be compiled afresh for each culture.

D Long before they can say anything at all, infants reach out and point. Pointing appears at around the end of the first year, weeks or months ahead of a child's first spoken word, and it is one of the surest early signs that a baby has begun to share attention with the people around it. By directing an adult's gaze towards a distant object, the infant is already doing what language will later do more precisely: drawing another mind towards a chosen part of the world. Children who point early tend, on average, to start speaking sooner, as though the hand were quietly preparing the ground for the voice that follows.

E Gesture does not only assist the listener; it also assists the very person producing it. When speakers are told to keep their hands still, they become noticeably less fluent, pause more often and struggle to retrieve the words they are hunting for. Experiments in which people describe how they solved a puzzle show that moving the hands lightens the mental effort of talking, freeing memory for other work and making it easier to hold an idea steady while a sentence is assembled. On this view the hands are not merely broadcasting a thought that is already finished; they are part of the machinery that helps to build it in the first place. The effect seems to grow stronger as a task becomes harder: the more demanding the idea a person is struggling to put into words, the more the hands come to the rescue, sketching shapes and directions in the air that the mouth has not yet found.

F Perhaps the most surprising discovery concerns moments when the hands and the voice disagree. A child asked why two rows of coins contain the same number may insist in words that one row has more, while the hands quietly say something else, matching the coins one to one. Researchers call this a gesture-speech mismatch, and far from being mere muddle it is a dependable signal that the child is standing on the threshold of a new understanding. Learners who produce such mismatches are the ones most likely to profit from teaching, and skilful teachers, whether or not they realise they are doing it, read these silent clues and adjust their explanations to suit. Some researchers have gone further still, deliberately teaching children to make particular gestures as they work through a problem, and have found that the right movement of the hands can nudge a wavering learner towards the correct answer. Thought and gesture, it seems, are woven together far more tightly than we usually notice.