Kindness doesn't pay—at least not between the hours of 9 and 5, a new study shows. The aptly-named "Do Nice Guys—and Gals—Really Finish Last?" study found that "agreeable" workers earn less than those who aren't as agreeable, with an especially wide gap for male employees. Men with below average agreeableness earned around 18% more per year than their more agreeable colleagues; less agreeable women earned about 5% more.
Researchers drew their findings from data gathered by three different surveys from the past 20 years. "Nice guys are getting the shaft," says a study co-author. "The problem is, many managers often don't realize they reward disagreeableness." Researchers suggested that, for men, being agreeable might not conform "to expectations of 'masculine behavior.'" Agreeable people may also be less assertive when negotiating salary, the Wall Street Journal notes. (Click for another trait that can impact your salary.)