So, what are we doing with these hand movements? Like so many aspects of behavior, there isn't just one use of hand gestures in communication. Some of these uses of gestures are quite subtle. Over the next few posts, we'll look at some of the roles of hand gestures in communication. For now, we'll focus on verbal communication. Obviously, sign languages use the hands for much more detailed forms of communication.

Some hand gestures are communicative by convention. These gestures allow people to communicate at long distances where voices might not carry. A wave of greeting, a thumbs-up sign indicating approval, or an index finger pointing that we're number 1 are all examples of conventions that have been established to communicate whole phrases in a gesture.

There are other gestures that communicate within a sentence being spoken. A good example of these are pointing gestures in which the speaker identifies an object in by pointing at it. For example, at the store, you might indicate which item you want to buy by pointing and saying, "I want that one."

Still other gestures help us to keep the beat of our speech. People who are lecturing or giving a formal speech will often move their hands in time with what they are saying. These hand gestures play a role in coordinating the timing and pacing of what is being said.

One interesting role of gestures is that they can help people to find a word. We all have had the experience of knowing what we want to say, but not being able to find the word. This kind of tip-of-the-tongue phenomenon can be quite frustrating at times. Gestures can sometimes help you out with that.

For example, Frances Rauscher, Bob Krauss, and Yihsiu Chen did a clever study reported in a 1996 issue of Psychological Science. They had people watch a cartoon of a chase between Wile E. Coyote and the Road Runner. Afterward, they had to describe the cartoons to someone else. In some cases, they were able to gesture normally. In other cases, their arms were strapped to the arms of a chair. (Participants were told that their arms were strapped down so that physiological measurements could be taken, although no actual measurements were taken.)

What is going on here? When people are speaking, they must translate their thoughts into the particular words they are going to use to talk about them. At times, they may have a mental image of something (like Wile E Coyote running toward a cliff), but they may not be able to think of the words right away. The mental image is one cue to that might help retrieve the word. Gestures that relate to the word can form another cue to help retrieve it. For example, when thinking about Wile E. Coyote running, a gesture that captures that movement serves as a retrieval cue for words about space and movement.

One important aspect of these gestures is that they do not seem to be primarily for communicating. For example, people still make these gestures even when they know nobody can see them. In addition, people listening to what is being said are equally good at understanding the speaker whether they can see the gestures or not. So, these gestures seem to be more useful for the speaker than the hearer.

Findings like this are relevant to the idea of embodied . That is, our ability to move and act on the world plays an important role in thinking. We might think of having a conversation as being about transmitting information from one person to another. However, in order to make that happen, we involve our entire body in the process.

In the next post, I'll talk more about how gestures may help us to learn things that we don't yet have a vocabulary for.