Research suggests that most people cannot tell from demeanor when others are lying. Such poor performance is typical not only of laypeople but also of most professionals concerned with lying. In this study, three professional groups with special interest or skill in deception, two law-enforcement groups and a select group of clinical psychologists, obtained high accuracy in judging videotapes of people who were lying or telling the truth about their opinions. These findings strengthen earlier evidence that some professional lie catchers are highly accurate, and that behavioral clues to lying are detectable in real time. This study also provides the first evidence that some psychologists can achieve high accuracy in catching lies.
Ekman, P., O’Sullivan, M., & Frank, M. G. (1999). A few can catch a liar. Psychological science, 10(3), 263-266.
https://doi.org/10.1111/1467-9280.00147