The world of sports has seen its fair share of wrongdoers during the past few years. From cheaters to liars to dirty players, we've had it all.

And while some of these athletes seem genuinely remorseful for their misdeeds, others have remained aloof. It appears to be pretty clear that baseball's all-time home run leader, Barry Bonds, used steroids at some point in his career, so why won't he apologize?

Even when athletes do fess up, they don't always seem sorry (looking at you, Lance Armstrong).

This non-apology has become a frustrating phenomenon, and some Australian researchers recently sought to uncover its psychological origins. The study, led by Dr. Tyler Okimoto, of the University of Queensland Business School, found that not apologizing for a wrongdoing can actually boost a person's self-esteem.

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As part of his research, Okimoto conducted two experiments. In the first, he divided 228 adults (aged 18 to 77) into three groups. He asked the first group to think about a time when they had done wrong by someone and apologized, the second group to remember an instance when they wronged someone and refused to apologize and the third to think about a time when they wronged someone and neither apologized nor refused to say sorry.

According to a report of the findings in the Daily Mail, those who refused to say sorry experiencing a higher boost in self-esteem and felt greater levels of power than either of the other two groups.

In the second experiment, Okimoto actually had some of his subjects apologize for something they had done. One group wrote emails apologizing to someone they had wronged, another group wrote emails refusing to say sorry while a third thought of a time they had hurt someone but did not write an email.

Once again, those who refused to apologize reported higher levels of self-esteem than the other two groups.

"Taken together," the researchers wrote, "the results of these two studies provide converging evidence that there can be beneficial psychological consequences for individuals who refuse to provide an apology to the victims of their harmful actions."

So as disappointing as it may be to see a high-profile and extremely successful athlete like Armstrong or Ray Lewis refuse to show remorse for previous wrongdoings, at least we now know why they're not sorry.