Picture this: John is a dedicated employee. He comes in early, stays late, and always goes above and beyond. His bosses love him, and he's well-liked by his colleagues. John is loyal, and that's a great thing, right?

Well, according to a new study, company loyalty might have its downside. Researchers found that managers tend to eye their most loyal workers over less committed ones when it comes to handing down unpaid or additional assignments.

In other words, if you're a loyal worker, you might be more likely to get stuck with the grunt work.

Matthew Stanley, Ph.D., lead researcher on the study and a postdoctoral researcher at Duke University's Fuqua School of Business, explained: “Companies want loyal workers, and there is a ton of research showing that loyal workers provide all sorts of positive benefits to companies. But it seems like managers are apt to target them for exploitative practices.”

Stanley and his colleagues conducted a series of experiments, enlisting some 1,400 managers online to examine a fictional employee named John.

The managers all learned that John's company had budget constraints and needed to decide how willing they would be to give John extra hours and responsibilities but without any extra remuneration. Managers were often more willing to assign "loyal John" the unpaid tasks.

When a separate group of study subjects assessed recommendations about John, the letters commending John for being "loyal" appeared more ideal to managers who wanted to enlist him for unpaid tasks, than versions of John who was lauded for honesty or fairness.

Stanley noted: “Loyal workers tend to get picked out for exploitation. And then when they do something that's exploitative, they end up getting a boost in their reputation as a loyal worker, making them more likely to get picked out in the future.

“Most people want to be good. Yet, they transgress with surprising frequency in their everyday lives. A lot of it is due to ethical blindness, where people don’t see how what they're doing is inconsistent with whatever principles or values they tend to profess.”

Should you therefore avoid helping out? Stanley believes being loyal and generous with your time just has a few downsides. But it remains a positive trait.

“I don't want to suggest that the take-away of the paper is to not be loyal to anybody because it just leads to disaster,” Stanley said. “We value people who are loyal. We think about them in positive terms. They get awarded often. It's not just the negative side. It's really tricky and complex.”