The Disturbing Reason 'Once A Cheater, Always A Cheater' Holds True

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man cheating at a bar while his phone shows a missed message from home

If you’re currently in a relationship with someone who cheated on you, I’m sorry that you have come to this article. But hey, the truth hurts, so why not face it head on, right?

The phrase "once a cheater, always a cheater" has been floating around the relationship space for decades, and whether you believe it’s validity or not, results of at least one study seem to back it up.

Is "Once a cheater, always a cheater" true?

While this statement certainly is not true 100% of the time, and while reliable statistics on cheating are notoriously hard to come by because they rely on self-reporting, data suggests that, at the very least, people who do cheat are likely to become increasingly comfortable with doing so over time.

In 2016, researchers from University College London and Duke University found a link between the brain and dishonesty they believe confirms the validity of this logic, offering an explanation for the reasons cheaters continue with their shady ways.

In their paper, entitled "The Brain Adapts to Dishonesty," states that the more people lie for self-serving purposes, the more comfortable their brains become with them doing so as time goes on.

Using functional MRIs, they found that the region of the brain called the amygdala shows a decreased sensitivity to one's own dishonesty the more you lie.

The study's authors explain: “We speculate that the blunted response to repeated acts of dishonesty may reflect a reduction in the emotional response to these decisions or to their affective assessment and saliency.”

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That said, Neil Garrett, co-author of the paper notes that these findings need to be tested more specifically in the context of romantic relationships.

“The idea would be the first time we commit adultery we feel bad about it. But the next time we feel less bad and so on, with the result that we can commit adultery to a greater extent,” Garrett said.

In the study, participants were set up in pairs to test their capacity to lie. One was given a jar full of coins while the other was given a blurry image of the same jar.

The one with the clear view of the jar had to help the other with the blurry view. However, they were then told that they would receive a financial reward if their partner overestimated the number. This caused them to be more likely to lie.

Garrett added, “What our study and others suggest is a powerful factor that prevents us from cheating is our emotional reaction to it, how bad we feel, essentially, and the process of adaptation reduces this reaction, thereby allowing us to cheat more. With serial cheaters, it could be the case that they initially felt bad about cheating, but have cheated so much they’ve adapted to their ways and simply don’t feel bad about cheating anymore."

"Another possibility," he says, "is that they never felt bad about cheating to begin with, so they didn’t need adaptation to occur; they were comfortable with it from the get-go.”

According to these findings, the little lies we tell here and there can add up, causing us to become more comfortable with larger lies than we may have been in the past.

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Garrett also says that the study would need to be altered in order to assess what kind of impact cheating has on the amygdala.

“I think one of the key differences would be that cheating in relationships often takes place over shorter timescales than in my study. So whether adaptation takes place at slower time scales and whether it generalizes to other types of behavior we find aversive like adultery, violence, etc. are the key two things we’d need to test to start to answer this,” he said.

So, if you are dating a known cheater, it might be time to cut ties. And if you are the cheater, you may want to practice weaning yourself before it gets even worse.

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Shannon Ullman is a writer and editor at Healthline. She focuses on relationship, wellness, and lifestyle topics, and has bylines on Huffington Post, Elite Daily, PopSugar, and MSN.