Deception detection accuracy: the role of personally vs. ideologically justified opinions

Introduction: Several factors modulate accuracy in detecting deception (Vrij, 2008). For instance, Sowden et al. (2015) showed that inconsistency, between detectors and deceivers, in ideological opinion on controversial topics impairs lie detection, while neurostimulation of the right Temporoparietal Junction (TPJ) removes the impairment. In the forensic field, however, deceptions refer more to personal experience, rather than ideological opinions. This is the first study aimed at (1) comparing consistency between personally justified vs. ideologically justified opinions as modulator of deception detection, and (2) providing causal data (via TMS stimulation) on the role of the right TPJ in this modulation. Methods: Initially, 150 healthy (age 18-65) participants completed a questionnaire about 10 controversial topics (e.g., abortion), asking for ideological opinion (for vs. against), and presence (vs. absence) of related personal memories. Forty-eight statements (half true) were recorded in videos. Each statement reported an opinion and its justification (personal vs. ideological). In Experiment 1, videos were randomly administered to 62 participants (half females). Participants judged veracity of each statement, and provided confidence ratings in their judgments. In Experiment 2, the same procedure was replicated with 40 participants, while, at the beginning of each video, triple-pulse 10 Hz TMS was administered on right TPJ vs. Vertex. Data collection is not completed yet. Results: Data analysis will be performed when datasets are complete. Compared to inconsistency in opinions, we expect detectors to be more accurate when the opinion expressed by the deceiver is consistent with their own, and is ideologically justified. Contrarily, when personally justified, we expect detectors to be less accurate when opinions are consistent in deceivers and detectors. In line with Pfundmair et al.(2017), we also expect an overall effect of consistency of judge-actor sex. In Experiment 2, TMS administration over TPJ compared to Vertex (Sham) is expected to selectively impair self representation, reducing the advantage for opinion consistent trials ideologically justified, while neuromodulation of TPJ should increase the accurate deception of personally justified consistent opinions Discussion:Self-representation can interfere with the detection of deception (Sowden et al. 2015). While the involvement of self-representation was previously examined as agreement on ideological opinions between deceivers and detectors, we hypothesize that equally important is the agreement based on personal experience. We expect an opposite effect of ideologically-based vs experience-based agreement, which would show that self-referencing does not have an univocal role in detecting deception. Greater accuracy is expected in deception detection when the agreement is ideologically justified, and lower accuracy when the agreement is personally justified. By inhibiting TPJ activity via TMS, we will understand if with stimulation personally justified lies are more likely to be accepted as truth.