Can misleading hand gestures influence eyewitness testimony?

Abstract

A wealth of research has highlighted the susceptibility of eyewitnesses to misleading verbal questions. However, the role of nonverbal influence when questioning witnesses has been overlooked, even though substantive information can be conveyed in gesture. We report the first study to examine whether subtle hand gestures, conveying misleading information, can affect witnesses' reports of a crime event. Seventy-two adults (M = 30.031, SD = 17.93) watched mock-up CCTV footage of a theft and were questioned afterwards by an on-screen 'police' questioner. Across conditions, the 'police' questioner asked the same question, but varied the hand gesture performed alongside it. For each question (e.g. 'did you notice any jewellery?'), the accompanying gestures conveyed information that was absent from speech (e.g. gesturing a 'ring' or 'watch'). The data confirmed that participants' responses were more likely to concur with information conveyed in gesture. This study shows that misleading information can be conveyed to witnesses non-verbally and have a significant impact on the accuracy of testimony. The implications for police and courtroom practices are discussed.