Remember the middle-school taunt: “Is that a threat … or a promise?” If you want to get the most out of a threat in the adult world, don’t let there be any question about it: Look the part, suggests a new study.

In two experiments, people were more willing to give into demands for a larger share of $1 when the person asking for more money looked angry.

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“If you come in with a scowl on your face, they’re going to take your threat more seriously,” study co-author Lawrence Ian Reed, a researcher at Harvard University, told Today. “You might think a poker face would be better in a negotiation. But in a bargaining situation when you make threats, your facial expression could add credibility to what you are saying.”

During one of the experiments, 870 participants were given the task of splitting up $1 with someone else. If they couldn’t agree, neither would get anything. When an actress demanded 70 cents on the dollar with an angry expression, more people agreed than when she used a neutral expression.

So far, the researchers have only done the experiment with women making the demands; reactions to a threatening male could be different. And, threatening looks only apply in face-to-face interactions, obviously.

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“Until we see someone, we don’t know what makes them sweat, or what makes them angry or happy,” Reed told Today. “You can do a lot of things over the Internet now, but people still choose to have face-to-face meetings.”

One caveat: It won’t work if people can tell you’re faking. If you’ve got a serious negotiation coming up, dredge up some real emotion or take an acting class.

Photo: Thinkstock