What’s Left Unsaid : How Nonverbal Influence Compares with Verbal Influence

Eyewitnesses' memory reports can be altered when ambiguous post-event information is presented verbally during interviews. While recent research has identified that gestures can also act a source of influence in eyewitness interviews, it is unknown whether nonverbal suggestions can exert an influence to the same magnitude as those made verbally. To investigate this, 92 adults were interviewed about a crime video and provided with either verbal (speech) or nonverbal (gesture) suggestions during questioning that provided either factual or misleading information about the scene. The results revealed that both differed from controls, and that gestures exerted a similar level of influence as speech: As with speech, gestures led participants to giving both correct and incorrect responses. These results highlight that misinformation conveyed covertly through gestures as a form of suggestion that is comparable to overt verbal influence despite differences in the way in which they convey information.