From the Human Factors and Ergonomics Society (HFES) press release:
Recent world tragedies have led to an increased emphasis on the importance of deception training – especially at security checkpoints in airports, bus terminals, and train stations – that is designed to avert potential terrorist attacks. Past research on deception has identified the physiological and behavioral cues that can expose the individual liar, but most major terrorist acts involve two or more coconspirators. In their upcoming Human Factors article, “Social Indicators of Deception,” authors James E. Driskell, Eduardo Salas, and Tripp Driskell took a unique approach to examining “deception at the social level—cues to deception that arise out of the interaction between two people conspiring to lie . . . based on a transactional memory theoretical approach.”
To determine if the speech and behavior patterns between two suspects during an interrogative interview indicated whether or not they were telling the truth, the authors conducted a study in which an interviewer spoke to pairs of police officers and firefighters who were assigned either to describe a recent event in which they both took part (the truth) or to fabricate a story on the spot (deception). The results showed that truth-telling pairs exchanged glances, followed up on each other’s comments, asked questions of each other, and used assent words (“yes,” “agree”) more often than did those in the deceptive pairs.
“Deception has been studied as an almost exclusively individual-level phenomenon,” said Tripp Driskell. “You have a hard-nosed detective on one side of a desk and a suspect on the other. But there are many situations today, especially in security settings, in which the opportunity exists to question two or more suspects. The bottom line is that there are many occasions in which people conspire to lie or to deceive. In fact, many terrorist acts are carried out jointly by multiple participants or conspirators, and initial encounters with these suspects are likely to be in a group setting.”
“We believe that the key to distinguishing truthful dyads from deceptive dyads is the concept of transactive memory,” he continued. “Two people describe an event differently if they had actually performed that event together versus if they did not but are fabricating a story about an event that did not take place. When we are questioned about the event, we recall it also in a joint manner – you recall some information and I recall some information. This is not as evident when two people recall a story that is fabricated or that did not take place.”
This first-of-its-kind study could lead to a closer examination of the interview tactics of military and law enforcement personnel, and perhaps even a change in interview training and protocol. The authors plan to investigate how the presence of a second interviewer changes the dynamic of the interview and whether this prompts any additional social cues between the suspects.