Let the man choose what to do: Neural correlates of spontaneous lying and truth-telling

Many previous functional magnetic resonance imaging (fMRI) studies on deception used a paradigm of "instructed lies", which is different than other, more spontaneous forms of lying behavior. The present study aimed to investigate the neural processes underlying spontaneous and instructed lying and truth-telling, and to investigate the different mechanisms involved. This study used a modified sic bo gambling game with real payoffs in order to induce lying. In the spontaneous sessions, the participants themselves decided whether or not to lie, whereas in the instructed sessions they were explicitly told to respond either honestly or dishonestly. In the spontaneous lying (vs. truth-telling) condition, the subgenual anterior cingulate cortex (sACC) showed significantly higher activity, whereas the right dorsolateral prefrontal cortex (DLPFC), ventrolateral prefrontal cortex (VLPFC) and inferior parietal lobule (IPL) were more strongly activated when participants spontaneously told the truth (vs. lied). Our results suggest that the extra cognitive control required for suppressing the self-interest motives in spontaneous truth-telling is associated with higher activity in the fronto-parietal network, while the process of negative emotion in spontaneous lying induced greater involvement of the sACC. Although similar to spontaneous deception, instructed deception engenders greater involvement of the right inferior frontal gyrus (IFG), left supplementary motor area (SMA), anterior cingulate cortex (ACC), IPL and superior frontal gyrus (SFG) compared to baseline, instructed decisions did not elicit similar activation patterns in the regions of sACC, DLPFC, VLPFC and IPL which were sensitive to either spontaneous truth-telling or lying.