A circuit in the brain that functions like a lie detector, has been discovered by Scientists from Oxford University.
Humans have the ability to imagine what others are thinking and learn from their social habits - giving them clues as to when something is incorrect.
The findings could also help explain why some people become paranoid, reports the Daily Mail.
Lead author Matthew Rushworth, of Oxford University, and colleagues scanned volunteers' brains while they chose one to two boxes to win points.
The participants were sent advice on which box to choose from a second player who was sometimes dishonest.
When the volunteers suspected they were being lied to, activity levels in the dorsomedial prefrontal cortex (DPFC), an area near the front of the brain, rose dramatically.
If a volunteer thought the player was telling the truth the brain activity remained low.
If their suspicions were proved wrong, the brain activity changed, suggesting the volunteers needed to rethink their opinion of the second player.
The activity was predicting how trustworthy the advice would be, then reacting to the results of that prediction.
Failures of this system could explain why those with schizophrenia are often paranoid.
The work was presented at a Cell Press Lablinks conference in London earlier this month.