You may think true love is stopping you from cheating on your partner but a group of scientists have argued there's a far less romantic explanation.
"People in monogamous relationships can experience a conflict when they interact with an attractive individual," scientists from Rutgers University and New York University explain in a new study.
"They may have a desire to reomantically pursue the new person, while wanting to be faithful to their partner.
"We suggest that one way people defend their relationships against attractive individuals is by perceiving the individual as less attractive."
The scientists have coined this phenomenon "perceptual downgrading".
The scientists conducted a three-part study in order to test the theory of perceptual downgrading.
In the first, they showed a group of 54 heterosexual volunteers two male and two female arrays of faces.
Each array consisted of 11 images – one original image and 10 images of the same face thay had digitally edited to make the face more or less attractive.
The faces varied on things like symmetry and evenness of skin tone, which are qualities previous research has shown to be associated with attractiveness.
When the researchers asked participants to pick a face they liked, they consistently picked the faces morphed toward attractiveness. This part of the experiment purely showed the researchers they were on track with their digital editing.
Next, the researchers set to answer two related questions: Do people in relationships perceptually downgrade attractive people who are potential threats to their relationships? And are they more likely to do that if they are highly satisfied with their current partners?
In the next phase of the study, the researchers told participants that they would be working with a very attractive – but, unknown to the participants, entirely imaginary – person.
Sometimes the researchers let the participants know this person was in a relationship and, thus, romantically unavailable; sometimes, they let them know he or she was single.
The researchers asked the participants some questions about themselves, including questions about their own romantic status. Eventually, they were shown the imaginary person’s face with its 10 morphed images and asked to pick the image that matched the original.
They consistently picked images morphed toward unattractiveness.
In the final phase of study, the participants provided more information about their own romantic situations. The researchers always described the imaginary person as single and therefore available.
They also told participants whether the person was interested in finding a partner.
Participants in relationships who thought the person was interested in dating found that person less attractive than single people with the same information.
People who were in relationships and who were happy in those relationships, perceived the imaginary person as less attractive than any other participants.
"We often hear about the reasons why people cheat or divorce and we spend less time exploring the factors that help people stay together," lead author Shana Cole said.
"This study suggests that there are processes that may occur outside of conscious awareness to make it easier to stay committed to one's partner."
The study is published in the Personality and Social Psychology Bulletin.