Lying Under Pressure: Examining the Impact of Stress and Veracity on Verbal and Nonverbal Behaviors in Credibility Judgments

In four experiments, we investigated how stress influenced the perceived verbal and nonverbal behaviors of honest and deceptive senders and how it affected credibility judgments made by independent observers. We used the Maastricht Acute Stress Test to induce stress in senders. Independent observers evaluated videos (Experiments 1 and 3) or transcripts (Experiments 2 and 4) of these senders reporting honestly or deceptively. Our results showed that stress significantly influenced observers' judgments of nonverbal behaviors but had a limited effect on content evaluations (plausibility, believability, and accuracy). Instead, veracity predominantly shaped credibility assessments, with plausibility and believability emerging as indicators of truthfulness. The findings challenge the reliance on nonverbal cues in detecting deception and emphasize the need of considering situational factors. Furthermore, they underscore the importance of prioritizing verbal content in professional lie-detection practices.