Science reveals what it may say about your personality if you're still friends with your ex

If you recently noticed that your ex unfriended you on Facebook (go ahead and check -- we'll wait), it could be because the person caught wind of new and somewhat disturbing psychological research.

A study published by researchers at Oakland University found that people with "dark" personality traits -- i.e., those who are generally disagreeable, manipulative, and exploitative -- were more likely to be friends with former flames for practical and sexual reasons.

Here's how the researchers arrived at those findings. First, they asked about 350 people to come up with a bunch of reasons for staying friends with an ex. They boiled those reasons down to about 150 factors and divided them into categories including reliability/sentimentality, pragmatism, and sexual access.

For example, "They were a great listener" would fall under reliability/sentimentality; "I wanted money from them" would fall under pragmatism; and "We still had sex from time to time" would fall under sexual access.

Then researchers asked another group of about 500 people to rate how important each of those approximately 150 reasons were in staying friends with a hypothetical ex.

Finally, the group of 500 took personality tests that measured dark personality traits as well as honesty.

Dark personality types generally value sex and short-term relationships, value money and power, and can be more manipulative.

Results showed that participants who scored high on measures of dark personality -- in particular the "antagonism" dimension -- were more likely to cite pragmatic reasons for staying friends with an ex. Meanwhile, participants who scored low on honesty and humility were more likely to cite reasons related to sexual access.

These results make sense, given that previous research has found that dark personality types value sex and short-term relationships over longer relationships, value money and power, and can be more manipulative.

Other interesting findings: In general, people rated reliability/sentimentality as the most important reason for staying friends with an ex. Pragmatism and sexual access were rated as the least important.

As for gender differences, men were more likely than women to say pragmatic factors and sexual access were important reasons for staying friends with an ex.

The takeaway here is not that if you're friends with someone you used to date, you should check them or yourself into a hospital. In fact, if your postrelationship friendship works fine and makes you happy, then you probably don't need to do anything.

But if you notice that your ex comes around only when he or she is in the mood, or broke, or when the person finds out you have a hot friend, beware. It could be a sign the person is not the most stable or benevolent person in your life -- and that you'd do well to spend less time with that ex.

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