Decades ago, Richard Nixon popularized the “madman theory” of negotiations. It suggested that demonstrating a willingness to consider “madness”in action would provide you with negotiating leverage. If your adversary believed that you really might do something extreme or even self-destructive, then you held more of the negotiating power, even if you were too rational ever to actually carry out the threat.

Consider tryingthis madman approach when you negotiate your next business deal: start by being nice and cheerful, then flash some anger. Repeat as often as necessary, but always in that order. Never start with anger. It will throw your opponents off balance, making them think you’re unpredictable, if not a bit unbalanced, and they may be more willing to make concessions because of the uncertainty that a deal will get done.

According to research published in the Journal of Experimental Social Psychology by Marwan Sinaceur, an assistant professor of organizational behavior at INSEAD, “usually people don’t like uncertainty, so when the recipient sees that you are behaving in an unpredictable way, they feel that they’re not in control of what is happening in the negotiation.” Being “unpredictable” or “emotionally inconsistent” in business negotiations can give you an edge. But it’s all in how you begin.

It’s important that you don’t start with anger, Sinaceur’s research discovered. “There is a difference between expressing anger, then happiness then anger then happiness versus expressing happiness then anger, then happiness then anger,” writes Sinaceur in an article on the INSEAD website. “We found that the latter strategy is more effective in making others comply. Clearly, if you express happiness and positiveness at the beginning of a negotiation people are going to feel less threatened and, eventually, they’ll disclose more information to you. Start nice, make people trust you first, make people talk and confide in you before you get tougher.”

What should you do when you’re facing a “madman” across the table? Sinaceur offers three tips to protect yourself from the advances of a “madman.” The first tip is to take a break from the negotiation so you’re not facing or talking with your partner. This will help you literally cool down and step back from the situation. Second, he advises you think back to your original objectives and targets of the negotiation. Finally, always keep in mind that your opponent could be putting on a show with his or her emotions to leverage concessions.

But distinguishing between real and phony anger can be tough, so Sinaceur advises defusing the situation by “non-verbally acting in a way that shows (e.g., keeping silent, smiling) that you’re not impressed.” Of course, your opponent may just think you’re crazy.