The impact of deception and suspicion on different hand movements

The present experiment examined the relationship between different types of discourse linked hand movements and deception. Hand gestures were experimentally studied during truth telling and deception, and in situations with either weak or strong suspicion. Participants (128 Italian psychology students) were interviewed twice about the possession of an object. In one interview they were asked to lie and in the other asked to tell the truth (veracity factor). In both conditions, suspicion was raised after the interview: Participants were accused of lying by the interviewer and asked to repeat their account a second time (suspicion factor). Results indicate that lying was associated with a decrease in deictic gestures, and an increase in metaphoric gestures (main effect of veracity). Also a decrease in self-adaptor gestures was found. Strong suspicion was associated with an increase in metaphoric, rhythmic, and deictic gestures and a decrease in self-adaptor, emblematic, and cohesive gestures (main effect of suspicion). No interaction effect was found.