Cerebral Cortex Advance Access published online on May 14, 2009
Cerebral Cortex, doi:10.1093/cercor/bhp090
The Truth about Lying: Inhibition of the Anterior Prefrontal Cortex Improves Deceptive Behavior
1 Institute of Medical Psychology and Behavioral Neurobiology, University of Tuebingen, 72074 Tuebingen, Germany, 2 International Max Planck Research School of Neural and Behavioral Sciences, 72074 Tübingen, Germany, 3 Department of Functional Imaging, Center for Diagnostic Radiology and Neuroradiology, University of Greifswald, 17489 Greifswald, Germany, 4 Department of Physiological Psychology, University of Salzburg, 5020 Salzburg, Austria, 5 Ospedale San Camillo, IRCCS, Istituto di Ricovero e Cura a Carattere Scientifico, 30126 Venezia, Italy
Address correspondence to Ahmed A. Karim, Institute of Medical Psychology and Behavioral Neurobiology, University of Tuebingen, Gartenstrasse 29, 72074 Tuebingen, Germany. Email: ahmed.karim{at}uni-tuebingen.de.
Recent neuroimaging studies have indicated a predominant role of the anterior prefrontal cortex (aPFC) in deception and moral cognition, yet the functional contribution of the aPFC to deceptive behavior remains unknown. We hypothesized that modulating the excitability of the aPFC by transcranial direct current stimulation (tDCS) could reveal its functional contribution in generating deceitful responses. Forty-four healthy volunteers participated in a thief role-play in which they were supposed to steal money and then to attend an interrogation with the Guilty Knowledge Test. During the interrogation, participants received cathodal, anodal, or sham tDCS. Remarkably, inhibition of the aPFC by cathodal tDCS did not lead to an impairment of deceptive behavior but rather to a significant improvement. This effect manifested in faster reaction times in telling lies, but not in telling the truth, a decrease in sympathetic skin-conductance response and feelings of guilt while deceiving the interrogator and a significantly higher lying quotient reflecting skillful lying. Increasing the excitability of the aPFC by anodal tDCS did not affect deceptive behavior, confirming the specificity of the stimulation polarity. These findings give causal support to recent correlative data obtained by functional magnetic resonance imaging studies indicating a pivotal role of the aPFC in deception.
Key Words: frontal cortex • lie detection • moral cognition • neuroethics • skin-conductance response (SCR) • transcranial direct current stimulation (tDCS)