It pains me to say this, but men and women are different—very different—in how they approach negotiation.

And guess what? Men are winning, winning, winning.

That's the distressing conclusion of a recent study reported in the Harvard Business Review by Leigh Thompson, a professor at the Kellogg School of Management at Northwestern University.

Thompson writes: “Our findings suggest that under normal conditions, men engage in unethical negotiation tactics more than women do, largely because males tend to be more competitive. Women tend to act more empathically, leading to less deceitful behavior on their part.”

Exactly how “unethical” and “deceitful” are men in negotiations? Thompson cites “substantial research” that shows men tend to lie more easily than women, and that they believe lying is acceptable. Moreover, men will use underhanded techniques to gain advantage, “such as looking at confidential reports not intended for them.”

Let's take a pause here. It's not that men have a more aggressive style. They cheat!

What's worse, women keep getting outsmarted by the brutes. “Even the most qualified, elite professional women—including those with MBAs from top programs and decades of experience—fared worse than their male counterparts at the bargaining table,” writes Thompson.

The upshot is that men are outgunning women at the negotiation game. And that negative repercussion carries over to what women earn, contributing to that gender gap in pay.

So what's the fix? To me, it's quite obvious that men should stop their lying and cheating and get in touch with their inner Boy Scout.

According to Thompson, both sexes need readjustment. Women need to see negotiation as a high-stakes competition in order to “unleash the inner tiger,” she writes. And men need to lower the temperature on competition and use more empathy to understand that “any ill-gotten win may come at some real cost for others.”

In one experiment, Thompson found that the gap between how men and women approach negotiation narrowed when participants were told how families would be affected by their actions. In that “high-empathy” scenario, only 22 percent of men acted unethically versus 16 percent of women.

Not to be a downer, but I'm not holding my breath that men will take a more nuanced approach to negotiation. Seriously, who's going to propose an empathy break during a high-stakes negotiation?

The sad truth is that it's probably up to women to wise up to the darker art of negotiation. And that's something businesses seem increasingly aware of.

In fact, Thompson tells me that corporations and law firms have hired her to work with women to help them be more effective at the negotiation game. So I was curious: Does that mean firms want Thompson to teach women to be more aggressive in their advocacy on all fronts, including their own careers and compensation?

Well, not quite.

“Some of the law firms I spoke to wanted me to address the salary issue head-on,” says Thompson. “But other firms wanted me to avoid that issue, and get the focus on how female partners could be more effective in terms of negotiating on behalf of their clients.”

In other words, firm management wants women to be tigers at the negotiation table for the greater good of the firm's business. But forceful advocates for themselves? Oh, let's not go there.

You got to hand it to them. Those boys in management are clever.

Contact Vivia Chen at [email protected]. On Twitter: @lawcareerist.