Non-verbal cues in eyewitness testimonies do not predict accuracy or credibility assessments

Non-verbal behaviour, such as facial expressions and body language, plays a critical role in assessments of witnesses' credibility that inform legal decisions in cases involving crime. While prior research has primarily focused on associations between non-verbal cues and deception, this study investigates the relation between non-verbal cues and recall memory accuracy in honestly reported mock eyewitness testimonies. Using a sample of 36 video-recorded eyewitness testimonies about a violent crime (n = 680 statements), we examined whether non-verbal cues were associated with statement accuracy (correct vs. incorrect), witness credibility as rated by independent observers, and witnesses' self-reported confidence. Additionally, we explored whether these associations differed for native vs. non-native speaking witnesses. Results revealed no associations between non-verbal cues and statement accuracy or perceived credibility. Furthermore, while non-native speakers were perceived as less credible, these perceptions were not related to non-verbal cues. Our findings contradict common beliefs by showing that non-verbal behaviour is not reliably related to accuracy or perceived credibility in eyewitness testimonies, highlighting the need for caution in their use in high-stakes legal contexts.