White lies may not be so innocent after all – study reveals selfish motives behind white lies using functional MRI brain scans

By Benedette Cuffari, M.Sc.Reviewed by Emily Henderson, B.Sc.May 28 2021

The term white lie itself suggests that the person telling the lie has good intentions; however, a recent study published in The Journal of Neuroscience found that people who told a white lie actually had selfish motives for telling that lie.

Truth/Lie Concept. Image Credit: OneSideProFoto/Shutterstock.com

What are white lies?

Although some people might have a tendency to lie on a consistent basis, several studies have found that about 95% of people, who are otherwise generally honest, will tell at least one falsehood each week. This statistic may appear shocking; however, a majority of the lies that most people tell on a weekly basis are small, white lies.

By definition, a white lie is an often trivial, diplomatic, or well-intentioned lie. More often than not, a white lie, which is a term that has been used since at least the 14^th century, is often used to protect someone’s feelings.

Selfish motives behind white lies

In addition to several other parts of the brain that are involved in human behavior, the medial prefrontal cortex (MPFC) is particularly important for human social cognition and behavior. Some of the specific social cognitive abilities that the MPFC has been shown to play an important role in includes self-reflection, the ability for humans to understand themselves and others, as well as the theory of mind/mentalizing.

In their recent paper titled ‘Neural Representation in MPFC Reveals Hidden Selfish Motivation in White Lies,' the researchers predicted that activity patterns within some subregions of the MPFC could provide information on the true motive behind white lies. To test this theory, study participants were provided a reward for themselves, for an unknown person, or for both themselves and the other person, after telling a white lie.

In order to determine the MPFC activity of the participants while they were telling these lies, a functional magnetic resonance imaging (fMRI) scan of the brain was obtained. Participants who told white lies with selfish motives were found to exhibit a greater level of activity in both the ventral and rostral regions of the MPFC as compared to those who told lies for altruistic purposes.