Think of the way hands form a fist for emphasis; spread out, palms up, in confusion; point out a direction to take or the size of a fish.

Everyone talks with their hands. But few realize how much they are saying.

"(Gestures) participate in communication, yet they are not part of a codified system," writes Susan Goldin-Meadow, author of "Hearing Gesture: How Our Hands Help Us Think" (Harvard University Press, $29.95). "As such, they are free to take on forms that speech cannot assume and are consequently free to reveal meanings that speech cannot accommodate."

So there. And gestures are important to the listener as well.

"We respond to (gestures)," says Goldin-Meadow. "We get visual input that adds to what is being said."

COURTESY OF QUIRK BOOKS

Pat Leo, a sign-language interpreter and actor who considers hand movements when developing a character, says gesture is part of human exchange. "It helps with emphasis, with clarification," he says. "It seems to keep the conversation going."

Emblems versus gestures

Universally known hand movements, such as the thumbs-up or the OK sign, are something different, says Goldin-Meadow. These are emblems, not gestures.

"(They) differ from gesture in that they don't depend on speech," she says. "Their meaning is well understood without a word being uttered." Body language might be more implicit, revealing emotions at times, but it, too, does not communicate the substance of a speaker's thoughts, says Goldin-Meadow, who is professor of psychology at the University of Chicago and has studied gesturing for about 30 years.

COURTESY OF QUIRK BOOKS

Gesture is a natural response. Attempts to think about gesturing risk the spontaneity that makes gesture honest and natural for the speaker.

"It should appear as natural as possible," says Leo, who adds that his interpreting work makes him more conscientious about what his hands convey. "It gives an extra dimension of reality. Seeing an actor that doesn't gesture at all is unnatural."

Its instinctive nature, adds Goldin-Meadow, makes gesture easily recognizable but not something that can be learned.

The same goes for a listener, who regularly understands the context presented by spontaneous gesture but is rarely aware of understanding the same gesture. To become entangled in what the hands are doing risks tuning out what is said out loud.

COURTESY OF QUIRK BOOKS

Plays role in education

Gesture also plays an important role in education, says Debbie Weaton, a third-grade teacher in Stamford, Conn. "On a subconscious level, I read what (my students) are telling me with their hands," she says. "And gesture doubles what you're saying."

Weaton also grasps her students' understanding of a particular point or lesson. "Some children are visual learners and gesturing helps them," she says.

"I do it naturally," says Weaton. "I want to make sure they are paying attention to me."

COURTESY OF QUIRK BOOKS

Cultures vary in use

Everybody gestures, but not everybody does it as often.

"The evidence is up in the air about whether a culture gestures more or less," says Goldin-Meadow.

"Spanish and Italian are cultures that seem to gesture big, away from their body. But the rate of gesturing may not diverge so much. The Italian culture has more emblems. Chinese culture has more emblems, too. Whether there are more spontaneous gestures is an open question."

Goldin-Meadow also studies whether native languages influence gesture. "To gesture like a native speaker you might need to see (gestures) or maybe the music of the language teaches gesture," she says.