Deception detection can be of great value during the juristic investigation. Although the neural signatures of deception have been widely documented, most prior studies were biased by difficulty levels. That is, deceptive behavior typically required more effort, making deception detection possibly effort detection. Furthermore, no study has examined the generalizability across instructed and spontaneous responses and across participants. To explore these issues, we used a dual-task paradigm, where the difficulty level was balanced between truth-telling and lying, and the instructed and spontaneous truth-telling and lying were collected independently. Using Multivoxel pattern analysis, we were able to decode truth-telling versus lying with a balanced difficulty level. Results showed that the angular gyrus (AG), inferior frontal gyrus (IFG), and postcentral gyrus could differentiate lying from truth-telling. Critically, linear classifiers trained to distinguish instructed truthful and deceptive responses could correctly differentiate spontaneous truthful and deceptive responses in AG and IFG with above-chance accuracy. In addition, with a leave-one-participant-out analysis, multivoxel neural patterns from AG could classify if the left-out participant was lying or not in a trial. These results indicate the commonality of neural responses subserved instructed and spontaneous deceptive behavior as well as the feasibility of cross-participant deception validation.
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