The origin of pointing

If you stopped someone in the street - or even in the most remote place on Earth - and started to try and communicate with them, the interaction would probably involve a lot of pointing and gesticulating as you both attempt to get your points across. Surprisingly, we’ve probably got our baby selves to thank for the fact that we can all do this, as Ankita Anirban heard from Cathal O’Madagain from CNRS in Paris...

Ankita - Pointing is the universal language. If we're on holiday somewhere and we don't speak the language most of us will resort to pointing and smiling to try and communicate with other people. In fact, pointing is one of the first things that babies learn to do.

Cathal - What's remarkable about pointing gestures is that we use them to coordinate attention. So when you point something out to somebody you are looking at the object, typically, and you get them to look at it and then you look at each other and you acknowledge “Hey look at that, isn't that interesting?” This is crucial for all sorts of human cooperative interaction. Infants all over the world develop pointing gestures in exactly the same way at around the same age.

Ankita - So is pointing a special human trait or do other animals also point?

Cathal - Other animals don't point spontaneously. Apes, our closest genetic cousins, or chimpanzees, they can be trained to point and to understand imperative pointing. This is where you point in order to get something handed to you, for example. But they don't do this spontaneously and in fact they have a very hard time understanding informative pointing. And this is remarkable because adult apes are so much smarter than nine month old infants, but nine month old infants understand this immediately.

Ankita - So when we point at something, what is it that we're doing?

Cathal - What we found was that, rather than pointing gestures working like arrows, people produce pointing gestures as if they're reaching their hands out to, quote-unquote, virtually touch an object in their field of view. So we tested this by looking at the angle of the index finger in a pointing gesture. Most people intuitively think that when you produce a pointing gesture you stretch your index finger out as an arrow that's directed at the object that you're pointing at. But we found that in fact, often the angle or the arrow that stretches out from your index finger leads nowhere near the object that you're referring to, but instead if you photograph somebody from the side while they're pointing at something and you draw a line from their eye through their fingertip this line will very accurately pick out the thing that they are referring to. And this suggests that there's some fundamental connection between pointing and touch and, of course, for us it suggests that pointing may originate in touch. In addition to producing pointing gestures at this funny angle, we also rotate our wrists when we're pointing at things that are out around a corner, for example.

So you imagine if there's a label on a bottle of wine oriented to the right, if you're asked to point at it you might find yourself rotating your wrist clockwise, so that the touch-pad of your finger is oriented to match the surface of the thing that you're pointing at, just as you would if you were reaching out to touch the label. And if you rotate the bottle around in the other direction, so that the label is facing to the left, you might find, if you're pointing with your right hand, that you'll rotate your hand, in a quite awkward movement, anti-clockwise. But again, just in the way that you would if you were trying to reach out to touch that label.

Ankita - But why would pointing be related to touch? Surely when we point at the moon we're not trying to touch it.

Cathal - So what we think is happening is that infants are exploring their environment by touching objects that they're paying visual attention to. They're looking at let's say an interesting toy and they're poking it with their index finger to see what it feels like. Parents then pay visual attention to what the infants are touching, so they discover that they can get their parents to pay attention to things by touching them. They then extend to objects further away from them, so they make as if to touch things in the distance and their parents then look at the object in the distance, looking for the thing that the infant is trying to touch and this is the origin of the pointing gesture.

Ankita - Well it makes sense that babies are always trying to get our attention and it seems to work. So not only do we all know how to point. We can also all interpret other people pointing very effectively. So what's the takeaway message of all of this?

Cathal - The pointing gesture originates in the coordination of visual attention with touch based exploration and this tells us something about the development of the pointing gesture within our lifetime in early infancy. But you can imagine that it also suggests a story about the evolution of this gesture and of human coordination that humans, as a species, seem to take real advantage of.