Pure Pedantry

"We've known for a while that we use gestures to add information to a conversation even when we're not entirely clear how that information relates to what we're saying," says Susan Wagner Cook, lead author and postdoctoral fellow at the University. "We asked if the reverse could be true; if actively employing gestures when learning helps retain new information."

It turned out to have a more dramatic effect than Cook expected. In her study, 90 percent of students who had learned algebraic concepts using gestures remembered them three weeks later. Only 33 percent of speech-only students who had learned the concept during instruction later retained the lesson. And perhaps most astonishing of all, 90 percent of students who had learned by gesture alone -- no speech at all -- recalled what they'd been taught.

Cook used a variation on a classic gesturing experiment. When third graders approach a two-sided algebra equation, such as "9+3+6=__+6" on a blackboard, they will likely try to solve it in the simple way they have always approached math problems. They tend to think in terms of "the equal sign means put the answer here,: rather than thinking that the equal sign divides the problem into two halves. As a result, children often completely ignore the final "+6."

However, even when children discard that final integer, they will often point to it momentarily as they explain how they attacked the problem. Those children who gestured to the number, even though they may seem to ignore it, are demonstrating that they have a piece of information they can't reconcile. Previous work has shown that the children with that extra bit of disconnected knowledge are the ones ready to learn, which suggests that perhaps giving children extra information in their gesture could lead to their learning.

Cook divided 84 third and fourth graders into three groups. One group expressed the concept verbally without being allowed to use gestures. The second group was allowed to use only gestures and no speech, and the third group employed both. Teachers gave all the children the same instruction, which used both speech and gesture.

After three weeks, the children were given regular in-school math tests. Of those children who had learned to solve the problem correctly, only a third of the speech-only students remembered the principles involved, but that figure rose dramatically for the speech-and-gesture, and the gesture-only group, to 90-percent retention.

What I take away articles like this is two things.

1) Cognitive psychology is genius. If half of teachers listened to what cognitive psychologists said, the number of untaught children in this country would plummet. Just look at how the ratio changed from 33% to 90% with just a tiny, tiny change.

2) Movement is a cognitive as well as a physical act. Because it is a cognitive act, it can modify other cognitive acts in the same system. We tend not to think of moving that way, but anomalous experiments like this make it clear.

For those of you who would like to read more, here is the current paper and an earlier paper Cook published on the same subject.

UPDATE: Language Log takes issue with some of the statistics in this paper:

OK, fair enough. I'm convinced that the use of hand gestures in this experiment improved the correlation between post-test performance and follow-up test performance. (Weiss's "three times" appears actually to refer to this difference in test-performance correlation, not to any difference in performance.)

The fact that use of hand gestures increased the correlation between post-test scores and follow-up test scores is interesting and meaningful. But I'd rather know how much the use of hand gestures actually improved follow-up test performance, and I'm puzzled that the authors didn't tell us that. Could it be because their experimental manipulation didn't produce a statistically significant difference in the follow-up scores either?

Read the whole thing. Susan Wagner Cook responds at the end of the post to clarify the issue.