The Truth about Lying: Inhibition of the Anterior Prefrontal Cortex Improves Deceptive Behavior

Institute of Medical Psychology and Behavioral Neurobiology, University of Tuebingen, Gartenstrasse 29, Tuebingen, Germany.
Cerebral Cortex (Impact Factor: 8.67). 06/2009; 20(1):205-13. DOI: 10.1093/cercor/bhp090
Source: PubMed


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.

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Available from: Ahmed A Karim
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    • "We did not choose a more posterior electrode as in previous studies (e.g. occipital cortex, Karim et al. (2010) and Bellaı¨che et al. (2013)), because of potential phosphene induction which could have interfered with stimulus processing in our experiment (Antal et al., 2003a, b). We used electrodes of two different sizes: 35 cm 2 for the active electrode, and 100 cm 2 for the return electrode. "
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    • "It is somewhat plausible that an intervention of the kind described here would increase Andrew’s moral conformity, and it is not fantastic to suppose that such an intervention might be developed in the future. After all, transcranial electrical brain modulation can already be used to alter rather specific mental abilities such as numerical competence [15] and the ability to deceive others [16]. "
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    • "However, null effects of cathodal stimulation have also been reported on complex verbal associative thought [11], associative verbal learning [5], verbal fluency [19], picture naming [6], working memory [20], contrast sensitivity in the visual cortex [21], and probabilistic classification learning [22]. Moreover, some have reported cathodal stimulation to cause facilitation in picture naming in aphasic patients [23], in comprehension in subacute stroke patients [24], and in deception in an interrogation following a thief role-play [25]. Although the facilitatory effect of cathodal stimulation in individuals with brain damage is often ascribed to successful suppression of abnormal cortical activity [24], this interpretation, even if correct, does not explain the variety of results obtained with cathodal stimulation. "
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