P300 amplitude at Pz and N200/N300 latency at F3 differ between participants simulating suspect versus witness roles in a mock crime

Based on the autonomic nervous system (ANS) study by klein Selle, Verschuere, Kindt, Meijer, & Ben Shakhar (2016), 15 participants pretended to perform a crime shown on a video, which 16 other participants pretended to witness. Both groups then experienced a P300-based Concealed Information Test (CIT) protocol called the complex trial protocol. Both groups showed CIT effects, with a larger probe than irrelevant P300s at Pz. However, this effect was significantly larger in the suspect group. In contrast, only the suspect group showed delayed N200/N300 responses at F3—putative inhibitory signs. This supports the klein Selle et al. (2016) ANS study in that the suspect versus witness role-playing manipulation differentially affected inhibitory (vs. orienting) aspects of the CIT situation. Our results are also consistent with Ambach, Stark, Peper, & Vaitl (2008), who saw the same autonomic response fractionation as klein Selle et al., but using Furedy's differentiation of deception method (Furedy, Davis, & Gurevich, 1988). These similarities are discussed.