Vital to everyday social and economic interactions is the ability to accurately discern whether other individuals are being honest or deceitful. While recognizing dishonesty is no easy matter, it is nonetheless possible even in the absence of signals from facial expression, through careful attention to nonverbal cues. Researcher Julie Grèzes and her colleagues have identified the brain mechanisms that underlie detection of deceptive intent through the use of fMRI technology.
The study involved imaging 11 participants as they viewed videos of actors with blurred faces lifting boxes, and evaluated whether the actors were attempting to deceive them regarding the weight of the box. The results from this experiment were compared to the results from a previous study in which participants were asked to judge whether actors' expectations of a box's weight were false. The key contrasting variable was the judgment of of deceptive intent in the current study, versus the judgment of a false belief resulting in accidental deception in the previous study.
Their research concluded that the amygdala and rostral anterior cingulate cortex were both significantly activated when the participants judged the actors as being intentionally deceptive, yet not when the actors were judged to have unknowingly erroneous beliefs that led to accidental deception.
The amygdala is known to be a critical aspect of the neural circuitry concerning emotion and value appraisal. Additionally, the anterior cingulate cortex is activated when there is intent to directly communicate with the participant, indicated by eye contact and use of the participant's name. Based on such, the researchers speculate that activation of the amygdala and anterior cingulate cortex may be suggestive of the observers' valuation of social intentions towards themselves, and could thereby reflect an emotional response to being misled.
Whether activated by an internal sense of fairness or rather an assessment of social intention, the amygdala and rostral anterior cingulate cortex are working together to help catch liars everywhere, red handed.
The original paper can be viewed at: http://www.jneurosci.org/content/24/24/5500.full?sid=4dc151cf-6709-4dae-b031-69ba24dc61c4