Why do all of us, regardless of our race, culture or language, wave our hands about when we speak? Why is it, for example, that when we are telling someone about pouring liquid, for example, we actually hold up a hand crooked into a ?C? shape and rock it back and forth a bit? Are we just following some sort of cultural convention and copying what, as children we saw others do to communicate similar concepts? Are we, for the benefit of the listener, visually illustrating the point that we are trying to get across verbally? Or does waving our hands about help us to think?

Frankly, no-one really knows. So to begin to answer some of these questions Jana Iverson and Susan Goldin-Meadow of Indiana University, Bloomington, Indiana have carried out an intriguing series of observational experiments on congenitally blind children and adolescents, that they now report in Nature. The team compared the amount, rate and type of gestures used by two groups of 9-19 year olds while they carried out reasoning tests known to elicit easily recognisable and comparable gestures. One group contained subjects who had been blind from birth and the other comprised age-, gender- and ethnically- matched, sighted, children.

Iverson and Goldin-Meadow found that blind participants, even when speaking to blind listeners, used gestures of more or less the same shape and rate as those employed by their sighted counterparts when conveying the same concepts. Indeed, all the youngsters, sighted or not, used their arms and hands while speaking, whatever the visual status of their listeners.

?Although our sample-size was quite small, this indicates very strongly that gesture goes hand in hand with speech - if you?ll excuse the pun,? explains Iverson. ?Our research was partly inspired by the observation that people waggle their hands about while talking on the phone, but we deliberately chose to investigate the use of gesture in young, congenitally blind people,? she continues, ?because they are a group who will have had little opportunity to learn or copy gesture from others.? Hence, because of their visual naïveté, the blind subjects? use of gesture to complement speech, hints that it cannot be wholly a product of culture or necessity, but may also, the team concludes, ?reflect or even facilitate the thinking that underlies speaking.?

Iverson and Goldin-Meadow now plan to look further into the cultural determinants of gesture. ?Sighted speakers of different languages are known to gesture at different rates - take for example the Japanese and the Italians,? says Iverson, ?so what we need to investigate next is whether or not gesturing differs in the congenitally blind from cultures such as these. Given our findings we would expect not, unless there are cultural and linguistic influences on gesturing that are transmitted via some route other than the eye.?