Researchers discovered a psychological trick that will make you a better negotiator

You've likely had some experience being the less powerful party in a negotiation. Maybe you tried to negotiate the terms of a job offer or petition your boss for a raise.

And you likely tried to make your case using numbers and facts that would appeal to the other party's rational side: "I can help the team double its output," or "I have been responsible for closing some of our biggest deals this year."

Yet new research suggests that one key strategy for winning a negotiation involves bringing some emotion to the table. Specifically, disclosing some personal information can elicit sympathy from the other party and help persuade them to see things from your perspective.

For the study, researchers at the University of California-Berkeley's Haas School of Business and New York University conducted a series of experiments comparing rational and emotional negotiation strategies.

In one experiment, nearly 100 undergrads were paired off and assigned the role of either "candidate" or "recruiter" before they simulated a job-offer negotiation. Specifically, the students had to negotiate the terms of issues including salary, health benefits, and job location.

All candidates received some background information about their situation: They recently graduated from a top university; they have had internship experience; this job would be a good fit.

They also learned that they had significant student loans to pay off and their mother was recently diagnosed with a life-threatening illness and their family is struggling to pay the hospital bills. They worried this might be their only chance at a job.

Half the candidates were told that gaining the other person's sympathy is a good way to succeed in a negotiation; the other half were told that it's wise to remain professional and make rational arguments.

Results showed that candidates told to elicit the recruiter's sympathy scored the better deal. In fact, when candidates appealed to recruiters' emotions, both parties walked away with a better deal.

Here's how Laura Kray, a professor at the University of California-Berkeley's Haas School of Business and one of the study's authors, explained the findings to Business Insider:

"Feeling the emotion of sympathy also helped information and communication between the parties so that they could come up with really out-of-the-box, creative solutions that they wouldn't have otherwise. So sympathy was sort of a social lubricant."

At the same time, Kray advised negotiators to use this strategy very carefully. Simply revealing a cascade of details about your personal life isn't necessarily a good idea.

But if you're the more vulnerable party in a negotiation, you could see how opening up a little bit and revealing a single point of weakness affects your rapport with your negotiating partner. You might find that it builds, rather than undermines, their trust.

Ultimately, this study reminds us that, even in professional contexts, we're all human.

"We often hold this idea of the workplace in some idealized sense as emotionless," Kray said. "We go in and we make decisions in a rational sort of calculating way, and we check our emotions at the door."

Yet Kray said this study "is part of a large recognition that emotions are central to our lives wherever we are, and that's true as well even at the bargaining table."