Most detective procedures center around hard physical facts and evidence, but what is the role of detecting nonverbal behavior?
A new study in the Journal of Nonverbal Behavior sought to challenge conventional wisdom that emphasized physical facts over nonverbal behavior. By replicating a previous study with slightly different variants, Dr. Eric Novotny and his team sought to fold in the role of nonverbal behavior detection in developing suspicions and driving along initial investigations into criminal wrongdoing.
The paper points out that much previous research actually casts doubt on the use of nonverbal detection in investigations. While there is a great deal of research finding that nonverbal detection can be effective, such research casts doubt on the claim that this is actually relied on by police investigators or even laypeople.
However, they contend that a distinction must be made between “discovering” and “suspecting” a lie. When we discover a lie, we have finished an investigation and concluded that a lie has taken place, but what causes us to initially suspect a lie?
The central contention is that suspicion does not depend on hard evidence because it is inherently the act of intuiting or suspecting that hard evidence would exist. Thus, suspicion has a critical role in leading to the investigation in the first place.
This is where behavioral cues and nonverbal detection come into the picture. It is in noting deviations from a behavioral baseline that individuals often come to conclude that something is being hidden or that deception is taking place.
In replicating previous work that emphasized the role of hard evidence, the current study asked not just what factors led participants to “discover” a lie but, in the treatment group participants were instead asked what led them to “suspect” a lie.
Each participant was asked to recall a previous time where they had caught somebody in a lie and to explain exactly what factors led to that conclusion. They did in fact find that most participants relied on hard evidence in order to discover lies, but the story for suspicion was very different.
Over forty percent of respondents pointed to nonverbal behavior as the stimulus for them beginning to suspect a lie, with only nineteen percent pointing to physical evidence.
This presented compelling evidence for the role of nonverbal behavior in beginning to suspect deception. To further drive home these points, the paper continued by conducting an additional study, this time asking more explicitly whether lies were discovered/suspected via hard evidence/behavioral evidence, dividing participants into a total of groups.
Again, their results confirmed the main hypothesis. People cited behavioral evidence much more often for determining suspicion, while they prefer non-behavioral evidence for discovering the truth.
This research helps contribute to the very important role of non-verbal assessments in deception detection. As has often been discussed, this is hard to do, so if you want to act on these conclusions, come check out Humintell’s own training programs on deception detection.