From The Ergoweb® Learning Center

Can You Tell When You’re Being Lied To?

In this study, researchers Driskell, Salas, and Driskell attempt to identify social cues that may indicate deception. That is, can we tell, especially in a field situation such as airport security, if two individuals are being deceptive? This research is quite different than many of the studies we review in The Ergonomics Report, yet it is a great example of the cognitive side of ergonomics (often referred to as human factors). We tend to cover topics that fall under the physical or organizational ergonomics domains, but today, we’ll discuss an example of the equally important cognitive ergonomics domain.

In their introduction, the authors note that there’s a long and sometimes “colorful” history to deception detection. They point to the polygraph testing (“lie detectors”), through which analysts attempt to measure and interpret physiological changes that cannot be detected by human observers, as one line of research. The other line of research, which is the path they use in this study, focuses on verbal and non-verbal behavioral indicators of deception that can be detected by trained human observers. The goal of this research study is practical: is there a way that human observers, such as military or transportation security personnel, can recognize the difference between truth and deception when two or more individuals are concurrently interviewed in a social setting, like a roadside checkpoint or airport security station. Previous research in this area tends to focus on a one-on-one interview situation, not a multiple person scenario.

Reviewing past research, the authors describe verbal behaviors of liars as:

  • fewer first-person-singular references;
  • fewer cognitive complexity words;
  • more negative emotion words.

Liars tended to exhibit non-verbal behavior such as:

  • more tense and inhibited
  • display fewer gestures
  • press their lips more
  • exhibit greater pupil dilation and voice pitch; and in certain conditions,
  • show less eye contact and more feigned smiling than those telling the truth.

Although the evidence suggests that these types of individual cues can be predictive of deception, the associations are generally weak, and they cite researchers DePaulo et al. as concluding, “the looks and sounds of deceit are faint”.

The previous one-on-one deception research tends to be laboratory based, under tightly controlled experimental protocols, whereas this research is field based, and includes a social interaction component. This appears to be the first research “that examines indicators of deception among pairs of persons who conspire to deceive and are interviewed at the same time.” The authors also describe law enforcement techniques as strongly favoring the immediate separation of suspects for individual interrogation, where the purpose is to extract a confession. The context of this research is field intelligence gathering, and those that might apply these outcomes would not be seeking a confession, but rather seeking to identify deceptive behavior. They describe application scenarios such as a military checkpoint at which a car with two or more people are briefly interviewed, and travel companions that might be briefly interviewed in the social context of an airport security station.

The authors describe the theory of transactive memory systems and the concept of synchrony or congruence as central to their study. Interested readers are directed to the complete article, cited below, for a detailed description of this research and its underlying theory. In short, transactive memory systems theory refers to the way a group stores and retrieves memories, and synchrony refers to how synchronous the group members recall and present those memories (they describe this as “co-occurance of behavior” between the members of the group). In a transactive memory situation, individual group members tend to remember or recall certain things about an event, while others recall other things about that same event.


Fifty-two police and firefighters (50 males; 2 females; between 1 and 26 years of experience) were recruited and randomly assigned in pairs to either “truth” or “deception” experimental conditions. Each pair were partners in their real-world jobs. For the truth experimental condition, the pairs were asked to describe a In the truth condition, they were asked to simply describe an actual situation that they had jointly participated in during the recent past. In the deception condition, they were asked to fabricate a story, as realistically and believable as possible, on the spot, that did not take place. The pairs were given some time to prepare, then stood side-by-side to be interviewed by the experimenter, who was blind to which condition, truth or deception, the pair represented. the interactions were videotaped for future review by two independent analysts, and the pairs were thanked and dismissed.

The experimenters sought to measure synchrony using three variables:

  1. mutual gaze (the number of times a pair looked at each other);
  2. speech transitions (the number of times a person provided an elaboration or response that immediately followed the preceding person’s turn) ; and
  3. word usage (using the Linguistic Inquiry and Word Count (LIWC) language analysis program). Specifically
    • use of first-person-plural pronouns (i.e., we, us, our);
    • words related to tentativeness (e.g., maybe, perhaps);
    • words related to certainty (e.g., always, never);
    • negations (e.g.,  no, not); and
    • inhibition (e.g., stop, refrain, wait)
The key findings include:
  • truth-tellers gazed more at their partner than co-conspiring deceptive pairs, by nearly a 3-to-1 margin;
  • truth-tellers followed up their partner’s responses more often than co-conspiring deceptive pairs, with truth tellers averaging approximately seven transitions during a 5-min interview, compared to less than one transition for deceptive co-conspirators;
  • there was no evidence that first-person-plural usage differed between the groups;
  • there was a marginal difference between truth-tellers and co-conspiring liars in the use of words related to
    social processes:
    • truth-tellers used more assent words, such as “yes”
      or “agree” than deceptive pairs; and
    • truth-tellers asked more questions of one another than did
      co-conspiring liars.
As with all studies, particularly an exploratory study like this one, readers must exercise caution in interpreting and applying these results to real-world situations. The authors also point to these limitations:
  • the researchers don’t know whether the “truthful” scenarios described by the participants in the “truthful” pairs were in fact true;
  • previous research indicates that even “true” stories may have fabricated content, and vice-versa;
  • the co-conspirator participants in this study were given only a few minutes to construct a deceitful story, while real co-conspiritors will likely have more elaborate preparation for deceit should they be questioned, and it’s unknown whether such preparation could change the results of this study;
  • even with this evidence that co-conspiring liars may exhibit behavioral cues, it remains to be seen whether interviewers, even with training, would be able to effectively recognize those cues.
How This Applies To Ergonomists
The field of ergonomics is much larger and more diverse than the health, safety and wellness topics that often dominate these pages and the marketplace for physical ergonomics services. This example from the cognitive ergonomics domain demonstrates one type of significant value our science and practice brings to society. Given the security concerns that have arisen world-wide in the face of what is commonly referred to as terrorism, research like this can play an immediate and effective role. However, this type of research can also be misapplied, and as the authors caution, great care should be taken when extrapolating this type of information to real-world applications. Echoing the previous quote from DePaulo et al., “the looks and sounds of deceit are faint,” and a society that values its freedom must balance potentially intrusive surveillance techniques with the principles of human rights and individual liberty. In essence, as research like this moves into the realm of practice, it’s important that security personnel are able to accurately assess deceptive behavior without incorrectly identifying truthful behavior as deceptive (that is, in terms of human error, that they don’t commit errors of commission, and in terms of statistical error, that they don’t make Type I and type II errors — false positives and false negatives, respectively). The consequences of security errors are very real, and can be quite severe, and therefore must be tempered in recognition of the limitations inherent to these findings. As the only field dedicated entirely to the interactions of humans with systems, we have a central role to play in many arenas, including security.
And don’t be surprised if you begin to recognize these and other ergonomics/human factors derived techniques appearing at an airport security checkpoint near you. Some of our field’s contributions are already well established in these environments, and more are sure to come. For examples, see the “Possibly related articles” section, below.


James E. Driskell, Eduardo Salas and Tripp Driskell, Social Indicators of Deception, Human Factors, published online 11 May 2012, available to Human Factors subscribers at

This article originally appeared in The Ergonomics Report™ on 2012-05-15.