Nodding or shaking the head not only signals how you're feeling about something, but also can influence how you feel about a subject, researchers have found.

"We think of nodding or shaking our head as something that communicates to other people, but it turns out that it is also communicating to ourselves," said Richard Petty, a professor of psychology at Ohio State University and co-author of the study.

It appears in the current issue of the Journal of Personality and Social Psychology.

To some extent, nodding or shaking your head can serve as a kind of "self-validation" that confirms to us how we feel about our own thoughts, he explained.

"If we are nodding our heads up and down, we gain confidence in what we are thinking, but when we shake our heads from side to side, we lose confidence in our own thoughts."

Petty and doctoral candidate Pablo Brinol, now teaching in Spain, did experiments with college-student volunteers.

In the first experiment, the students were told they were testing the sound quality of stereo headphones, particularly their performance while the subjects were jogging or dancing.

Then, half the students were told to move their heads up and down about once per second, the other half from side to side, while listening to a tape.

All heard a supposed campus radio broadcast that included music and different versions of an editorial advocating that students be required to carry personal identification cards at all times. One version of the editorial presented well-reasoned arguments; the other laid out poor arguments.

Then, along with checking sound quality, the students were asked about their agreement with the editorial.

Those who heard the strong editorial agreed more with the message when they had been nodding "yes" than those told to shake "no" while listening.

But those who heard the poorly reasoned editorial had a reverse pattern: those who nodded "yes" said they agreed less with the message than those who were shaking their heads "no."

That's because their nodding movements increased their confidence that they were right about their negative thoughts toward the argument, Petty said.

"Nodding your head doesn't mean you'll agree with everything you hear," he said. "If you're thinking negative thoughts while you're nodding, this actually strengthens your disapproval."

In another test, students were asked to write down three good or bad qualities about themselves with respect to their planned careers. However, some were told to write left-handed and the rest right-handed -- although all were right-handed.

When asked to rate how confident they were about what they'd written, those using their dominant hand were more confident than those forced to write lefty. "Just having to write with the non-dominant hand shook confidence in what they put down," Petty said.

Petty said it's significant that body movement could affect confidence even in matters that are important to us and that we have considered closely, like career choices.

"That movement can influence us on our most important decisions, unconsciously, when we are being very thoughtful, that makes this dangerous in some sense.

-- Lee Bowman's e-mail address is BowmanL@shns.com.

On the Net: www.osu.edu

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Last updated: 07/20/2003 - 07:56 AM