In Brief

Quick, count how many blue books are on your shelf. If you're like most people, you probably pointed as you counted. At the very least, you mouthed the numbers to yourself.

These gestures are more than just habits left over from childhood, they actually enhance the cognitive processes that underlie counting, according to a new study in the July Journal of Experimental Psychology: Learning, Memory & Cognition (Vol. 33, No. 4).

Pennsylvania State University cognitive psychologist Richard Carlson, PhD, and his colleagues recruited college students to count scattered dots on a computer screen. Half of the students pointed to the dots as they counted, and the other half were told not to. The pointing students counted more quickly and accurately than the non-pointers, but researchers noticed something they hadn't expected: Many of the non-pointing students nodded their heads while counting. Were they replacing one gesture with another?

Carlson ran the experiment again, except this time he videotaped it, picked out the nodders, and found that they out-counted those who didn't.

In a third experiment, Carlson asked students to add up digits on a series of dice-like cubes. The digits differed between cubes, but each individual cube displayed the same number on all sides. One group of students could pick up and move the cubes as they added; the others could only look at the cubes on a table. When working with only a few cubes, the groups didn't show much disparity, but as researchers added more and more cubes, the participants who touched them significantly out-performed those who didn't.

For most adults, counting is second nature, so why does pointing or nodding help? Carlson thinks a few things may be responsible. For one, gestures set a rhythm- point, point, point- which previous studies have shown dramatically speeds up counting. At the same time, gesturing might help the mind keep track of things such as which dots have been counted or what number to add next tasks known as mental representations.

"Maintaining mental representations is pretty costly," Carlson says. "The gesture is a way to offload some of that burden."

-M. Price