When my 1998 Volvo finally broke down last year, my first worry was not about being carless, but about my impending trip to a car repair shop. It’s a common stereotype that women don’t know much about cars, and while there are plenty of car-savvy women, I’m not one of them. I knew that when the shop told me about all the costly new parts I needed, I’d have no way of evaluating whether they were being straight with me or taking me for a ride. And new research supports my fear: The stereotype that women are incompetent makes people more likely to lie to them during negotiations.

Researchers at the University of California–Berkeley and the University of Pennsylvania asked MBA students to participate in role-plays of face-to-face negotiations. The faux negotiation took the form of a real estate deal, where one student played the role of the buyer’s agent and the other the seller’s agent. The seller’s agent was directed to sell to someone who wanted to keep the property for residential purposes, but the buyer’s agent knew that the client planned to turn the seller’s property into a tourist hotel and had been explicitly instructed not to tell the seller this information. Thus, the student playing the role of buyer’s agent had to decide whether to tell the truth, or to lie.

“We found that in the role-play, people were significantly more likely to blatantly lie to women,” says Laura Kray, the lead author of the study. “To women, for instance, the buyer’s agents would say, ‘They will be luxury condos,’ but to men, they would say, ‘I can’t tell you.’ ” After the negotiation, students were asked to disclose whether they lied. Both men and women reported lying to women more often. Twenty-four percent of men said they lied to a female partner, while only 3 percent of men said they lied to a male partner. Women also lied to other women (17 percent), but they lied to men as well (11 percent). Perhaps even more telling: People were more likely to let men in on secrets. “Men were more likely to be given preferential treatment,” says Kray. In several instances, buyer’s agents revealed their client’s true intentions to men saying, “I’m not supposed to tell you this, but … ” This sort of privileged information was never offered to women.

Kray and her colleagues also asked students to rate the hypothetical buyers’ characteristics and found that participants perceived women as less competent than men (or a hypothetical person whose gender was not revealed). “When people perceive someone as low in competence and easily misled, they assume the person will not scrutinize lies, and that you can get away with [lying],” says Kray. Participants were asked to report how likely they thought other people would be to take advantage of a male or female buyer, and the participants correctly reported that people would lower their ethical standards when dealing with women. “People are aware of stereotypes, and use them to their advantage when they’re motivated to do so,” Kray says.

This set of experiments can’t tell us everything about how men and women fare in negotiations in the real world. Maybe these MBA students were more cutthroat than the average person, given that they were being graded on their negotiation skills. (There’s research suggesting that— surprise, surprise—business school students cheat more often than their nonbusiness peers.) Also, real estate transactions may not be the most realistic proxy for other real-life scenarios involving negotiations. Still, these studies show how women may be generally perceived in business transactions, where many of the players will be similar to the business student sample.

Kray suggests that it may help women in negotiations to signal their competence and confidence. She recommends showing up prepared, asking questions, and scrutinizing terms throughout the process. Her advice fits in with feminist campaigns that aim to empower women to take control of their careers: Facebook COO Sheryl Sandberg recommends leaning in to opportunities for success; media veterans Katty Kay and Claire Shipman instruct women to get ahead by being more confident.

But for all our leaning in and confidence-building, women’s attempts to reach the top can be stalled by factors we can’t control, like the gendered evaluations Kray and her colleagues uncovered in their study. Another study published last week echoes this finding: While white men are lauded for promoting diversity, women who do the same receive lower performance ratings and are perceived as less warm. Ultimately, encouraging women to act like men is a losing battle; the assertive moves that make men appear competent in the workplace backfire for women, who are perceived as cold and bossy instead. The problem doesn’t lie in women’s actual skills—it lies in stereotypes about what we’re capable of. And until we chip away at those, telling women to try harder won’t get us fair treatment.