Introverted employees may have it out for their more outgoing peers, according to researchers at Oregon State University, the University of Florida, and University of Notre Dame. Not only are introverts more likely to rate extroverted colleagues as worse performers at work, they're less likely to give them credit.

"The magnitude with which introverts underrated performance of extroverts was surprising," said Dr. Keith Leavitt, an assistant professor at OSU's College of Business and study co-author, in a release. "The results were very consistent across both studies." 

This notion that introverts' personalities could have such an impact at work spurred the researchers to investigate further. They decided to hold two studies. 

In the first, 178 students were each assigned to a four- or five-person project team for the semester, then asked to complete questionnaires about their team members midway through the term. Additionally, they were asked to share thoughts on how they got along as a team, as well as their own personalities. 

To the researchers' surprise, introverted team members rated other introverts higher than extroverts, while the extroverts didn't seem to be influenced by the personalities of their teammates at all. Could it be that introverts are more sensitive? 

The second study tested the theory further. Now 143 students in a management program were asked to participate in a 10-minute long online game with three teammates. And without the students' knowledge, one team member's profile was manipulated at random to highlight high introversion or extroversion--though their performance in the game remained constant, the researchers noted. 

After evaluating their team and making recommendations for promotions and bonuses, the researchers found that introverts gave poorer evaluations--and lower bonuses--to extroverted team members, though they performed just as well as their teammates. Again, the extroverted participants made their evaluations based on merit. 

According to Leavitt, the issue might be that extroverts just need to hit a "dimmer switch" when interacting with their taciturn peers. Employers should consider the personality traits of evaluators, which could bring a degree of bias into bonuses or other decisions. And they may also want to reconsider sticking that introvert in a team of extroverts since they do make better bosses, after all.