Are Agatha, Dashiell, and Arthur alive? Assessing the link between hand movements and false intentions

Background: With the ever-increasing political, ideological and social tension which followed 9/11, crime prevention stands as an issue of major relevance. The development of the ability to accurately detect statements of false intent is of great societal and legal value. It could aid intelligence services in preventing crimes (e.g., terrorist threats) and security services in reinforcing their protocols (e.g., airport security checks, parole hearings, and border control).Goals: To examine the associations between hand movements and false intentions in adults.Methods: Using a laboratory-based variation of the ‘Portsmouth design’, 23 students completed a questionnaire about their intentions to travel in the near future. Participants with a planned trip were placed in the truth tellers’ condition (n = 12). Those who did not have a planned trip were placed in the liars’ condition (n = 11). Based on the main theoretical approaches, three hypotheses were proposed. Hypothesis 1 advocated a decrease in the three categories of illustrators (movements interconnected to speech that serve to illustrate what is being verbally said) in liars, as compared to the truth tellers. Hypothesis 2 also suggested a decrease in the category of subtle hand and finger movements in the lying condition, comparatively with the truth condition. Finally, hypothesis 3 proposed a lack of significant differences between liars and truth-tellers in the five categories of self-adaptors (movements in which one part of the body does something to another body part, such as scratching the ear or squeezing the hands).Results: Hypothesis 1 was partially supported. The general and the unilateral categories of illustrators decreased in the case of the liars, as compared to the truth tellers; however, the bilateral category of illustrators slightly increased in the lying condition, in comparison with truth telling. Hypotheses 2 and 3 were fully supported. Discussion: Apart from the slight increase of bilateral illustrators in the case of the liars, all the results are in accordance with the empirical findings on deception research about past events. This similarity is noteworthy, considering the cognitive differences between lies about past events and lies about future events.