How long do you have to prove yourself in an interview? Half an hour? Fifteen minutes? University of Toledo researchers found that job seekers have under 30 seconds to make their mark on interviewers.

Since first impressions are sometimes made before job seekers even open their mouths, nonverbal communication -- or, body language -- is an essential part of any interview.

Seeing Eye-to-Eye

Some people make too little eye contact. Others make too much. The right amount, according to experts, lies somewhere in between.

"Make eye contact and periodically break away," says David Givens, Director of the Center for Nonverbal Studies in Spokane, Washington.

"The one caution I would give," he adds, "is that when you break away, do not look down. It gives connotations of submissiveness."

Be Forward Thinking

The interviewer offers you a chair. You sit down and lean back. You've already made your first mistake.

Always lean forward during a job interview.

"Leaning back shows an attitude of being too relaxed," says Givens. "Leaning to the side can connote that you don't like the interviewer."

Givens suggests leaning about 10 degrees forward.

Avoid Strong Expressions

Interviews are not personality parades. Nonverbal communication experts warn against showing too much expression during interviews.

"You want to show some positive emotion, but it has to be understated and conservative," says Givens.

The one exception is the handshake. For that, Givens suggests a "toothy smile."

Negative Signs

The successful candidate should also know what signs to avoid. These include:

• Hand behind the head: This is a universal sign that people are uncertain or annoyed, according to Givens.



• Palm-down gestures: Avoid these signs as they are generally reserved for authority figures. Flashing power signs in an interview might hint at a power struggle.



• Tilting heads: While Givens acknowledges that this is a "great courtship signal," he advises against it for the job interview.



• Laughter: Feel free to laugh along with the interviewer, but don't erupt into laughter on your own.