Brain Bias May Make Lies from Friends Feel More Believable, Especially with Potential Gains
Spotting dishonesty is not just about catching inconsistencies. People must read social cues, infer intentions, and decide whether someone’s words deserve trust. Scientists have long tried to understand how the brain performs this kind of social evaluation—and whether we judge information differently when it comes from a close friend rather than a stranger.
To examine that question, researcher Yingjie Liu of North China University of Science and Technology and colleagues studied how relationship closeness changes the way people assess potentially deceptive messages.
How the Study Tested Deception in the Brain
In research published in JNeurosci, the team used neuroimaging to measure brain activity in 66 healthy adults. Participants were paired and seated facing each other, but they interacted through computer screens so the researchers could tightly control what information was exchanged and when.
Each message carried a consequence framed as either a potential “gain” or “loss.” A gain meant the outcome would benefit both members of the pair, while a loss meant the outcome would be negative. Co-author Rui Huang said the gain-and-loss setup was chosen because it shows how people adjust decisions when rewards or punishments are at stake.
The results suggested that, in gain situations, people were more likely to accept false information as true. This increased susceptibility was linked to activity in brain regions involved in reward processing, risk evaluation, and interpreting other people’s intentions—indicating that the promise of a positive outcome can make a lie feel more believable, even when there are reasons to be skeptical.
Why Friends Can Be Especially Persuasive
One of the most notable findings involved friendship. When the communicator was a friend, the two participants showed synchronized brain activity. This “coupling” changed depending on whether the situation involved gains or losses.
During gain scenarios, areas related to reward tended to align more strongly between friends. During loss scenarios, regions tied to risk assessment showed stronger alignment. Using these patterns, the researchers could predict when a participant was likely to be misled by a friend.
The Bias That Makes Rewarding Lies Harder to Spot
Overall, the study points to a specific vulnerability: people may be more likely to believe falsehoods when the information suggests a shared benefit. At the same time, friendship appears to shape how the brain processes and synchronizes social information, which may make accurate truth-checking more difficult.
In combination, reward-driven thinking and interpersonal closeness can tilt judgment toward trust—making certain lies, especially those that promise something good, feel more convincing than they should.
