Study co-author Neil Garrett, a psychologist at University College London, told Elite Daily: "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 any more."
How the research was carried out
When we deceive someone, the part of the brain that regulates emotion - called the amygdala - is activated, and we can feel shame or guilt.
Dr Garret's team asked participants to play a game where they would sometimes get more money for lying to their partner.
They were shown a jar full of coins and asked to help a partner guess how many were in the jar.
The partner was only shown a blurry image of the jar.
But when they were told they would be rewarded if their partner over-estimated the amount of coins in the jar they were more likely to lie.
Brain scans of the volunteers confirmed that lying can be a slippery slope: people did lie more over time.
Their brains got desensitised to deceiving, and how much they were desensitised could predict how much more someone would lie the next time.
Their past does matter
Another recent study found similar results.
Researchers discovered those whose previous partners had been unfaithful before are twice as likely to be cheated on again, according to a paper published in the journal Archives of Sexual Behaviour.
That research looked at 484 participants of mixed-gender relationships and their sexual relations with someone other than their partner.
The results showed that people who had cheated in their first relationship were three times more likely to cheat in their next relationship compared to those who had stayed faithful.
And it also discovered that suspicion of cheating worsens over time.
Those who have suspected being cheated on in the past were four times more likely to accuse future partners of cheating, regardless of whether they had cheated or not.
- Daily