Effectiveness of Mental Countermeasures in Psychophysiological Detection of Deception

Background: This study examined the impact of mental countermeasures on the accuracy of the comparison question test (CQT) in psychophysiological detection of deception.Methods: Forty-five participants were randomly assigned to three groups: innocent, guilty, and guilty with mental countermeasures. A mock crime scenario was used, and the Utah Zone Comparison Test was conducted. Scoring was performed using the Empirical Scoring System–Multinomial.Results: The CQT accurately identified all guilty participants (100%) and 91.7% of the innocent participants. However, only 25% of the guilty with mental countermeasures participants were correctly classified, indicating a substantial reduction in detection accuracy due to the use of mental countermeasures.Conclusions: Mental countermeasures can significantly distort physiological responses, undermining the core assumption of the CQT. These findings emphasize the need for advanced detection techniques that integrate neurophysiological measures such as functional near-infrared spectroscopy (fNIRS) and machine learning approaches.