lie detection


Friends of the Nonverbal Communication Blog, this week we present the paper “A liar and a copycat: nonverbal coordination increases with lie difficulty” by Van Der Zee, S.; Taylor, P.; Wong, R.; Dixon, J. and Menacere, T. (2020) in which authors investigate whether interpersonal coordination increases or decreases when somebody is lying.

We have talked about deception, how to recognize it and the observable effects it has on people, several times so far.

For this reason, we already know that most studies on deception and nonverbal behavior focus on the behavior of the interviewees, who have the task of lying or telling the truth, and on the behavior of the interviewers, who have the task of determining the veracity of the story.

However, few consider the whole interaction.

This surprises authors, because the impact that the interlocutor has on the interviewee is part of the explanations of why behavior changes when we lie.

For example, it is believed that the increasement of cognitive effort associated with the lying process is due, in large part, to the need to create and maintain a coherent story while paying attention to the interviewer’s reactions.

That is, most of the literature suggests that behavioral signals of the cognitive and social processes of lying are probably best observed in a dynamic of interpersonal behavior.

One of these behavioral signals that seem fundamental, both for interpersonal interaction and for lying, is nonverbal coordination, the synchronous movements that occur between two or more people when they are sharing an interaction.

It is believed that this type of coordination may have evolved to allow individuals to maintain harmonious relationships with members of a group, facilitating social behavior.

However, in the animal kingdom, mimicking the behaviors of the preys is a deceptive technique that allows many predators to survive.

We can extrapolate it to human relationships if we think that, as described in an article mentioned in this work, there would be a greater coordination of head movement in deceptive conversations compared to honest conversations.

Authors believe that lying could affect interpersonal nonverbal coordination in two radically opposite ways.

On the one hand, lying could increase coordination following the idea that the cognitive demands of deception would leave the liar with fewer resources to control her/his social behavior.

Why? There are studies that suggest that leading one’s own rhythmic behavior, rather than following the behavior of the interlocutor, would require inhibiting the interlocutor’s actions, or at least improving the representation of one’s own actions. And this is a behavior that demands a great cognitive effort.

Therefore, if liars have fewer cognitive resources to manage their social cues, they could be expected to demonstrate greater coordination.

On the other hand, the other option is related to the tendency of people to paralyze in response to stressors or social threats. This “freezing” could lead to decreased coordination.

Signs of deception, such as pupil dilation or increased tension, could indicate that lying is indeed stressful. Thus, liars who “freeze” might be expected to show reduced coordination compared to people who tell the truth.

To verify this, authors carried out two experiments in which, basically, participants were explained that they should lie at different levels (simple, complex or very complex lies), infiltrate in a group, among other activities. What is interesting is that their nonverbal behavior was monitored while the participants carried out these tasks.

Among the results obtained are the following ideas.

The main and most interesting thing is that there seems to be evidence that nonverbal coordination increases along with the difficulty of lying.

This would be consistent with the first hypothesis, which maintains that mimicry would increase when the cognitive effort appears, due to a greater dependence on the automatic processes of interpersonal behavior.

Furthermore, this finding is consistent with the idea that automated processes can become more frequent when people are cognitively loaded.

Having obtained these results makes automatic mimicry a hitherto unexplored clue to deception.

When trying to appear credible, liars may implement countermeasures such as avoiding behaviors associated with lying or deliberately displaying behaviors associated with honesty. It could also be possible that the consequence of these effects may be reciprocal coordination, which has the effect of diminishing the interviewer’s ability to identify deception.

This would suggest that lying is not always more difficult than telling the truth, especially when it comes to simple lies.

In future investigations, the authors would like to investigate who is leading the change in the degree of coordination, whether the interviewee or the interviewer, since they consider it a very interesting point.

Friends of the Nonverbal Communication Blog, this week we present the paper “Pupil dilation reflects the authenticity of received nonverbal vocalizations” by Cosme, G.; Rosa, P. J.; Lima, C. F.; Tavares, V.; Scott, S.; Chen, S.; Wilcockson, T. D.; Crawford, T. and Prata, D. (2021), in which authors wonder whether a reaction by the autonomic nervous system exists when we listen nonverbal vocalizations and we judge if they are genuine or not.

Lie detection is one of the more controversial areas of study in nonverbal communication.

Not only body movements are studied when it comes about discover lies, but also the authenticity of the emotions showed.

This process is something we do voluntarily and involuntarily too, because the emotions we express and receive in social interactions are extremely important to stablish bonds. From a biological and evolutive point of view, they mark the difference between surviving or not.

Emotions can be expressed with nonverbal vocalizations and yet they can provide valuable information.

Crying, for example, is an intense emotional expression of a negative state often accompanied by lacrimation. In a social context, is assumed to have the purpose of eliciting help from listeners, or, in an interpersonal context, is understood to function as relief and improve mood after shed tears.

On the contrary, laughter is an emotional expression of a positive state and has the role of promoting and maintaining social bonding.

Authors say that previous studies have shown that some differences exist between real and faked laughter and cries. Authentic ones are often more highly pitched and longer in duration. Moreover, they have more variable pitch, lower harmonicity and less regular temporal structure.

On one hand, whereas genuine laughter is a reaction to a positive and surprising stimulus, acted laughter is associated with polite agreement and fake appreciation in formal contexts.

On the other hand, authentic crying is a genuine reaction to a negative stimulus, while acted crying is associated with manipulative social deception.

Authors explain that, according to previous works, interpreting non-authentic stimuli, and solving its ambiguity, is cognitively demanding. This is when pupil dilation comes into play.

Pupil size is used as proxy of arousal and cognitive effort in emotion research, and it depends on autonomic nervous system activity.

The pupil dilates with higher arousal elicited by a stimulus, thus, emotionally charged vocalizations evoke higher pupil dilation compared to the others. In addition, the pupil also dilates with cognitive effort, which is something we have already mentioned.

Considering what has been explained, authors wonder, for the first time, if the process of authenticity recognition in nonverbal emotional cues indues an autonomic nervous system response in the listener. The response would be the pupil dilation or contraction.

To carry out their study, authors have two hypotheses. The first prediction is that authentic vocalizations would elicit higher pupil dilation compared to acted, because they have been found to be more arousing in general, and pupil dilation increases with arousal.

Secondly, they ask themselves if authentic vocalizations would elicit lower pupil dilation, because authenticity discrimination, at least in laughter, has been found to decrease the cognitive effort.

A total of 28 people participated in the study. They were filmed while they listened to cries and laughter that were genuine or fake.

Results were interesting, because has been proved for the first time that authenticity recognition in human vocalizations has effects on pupil dilation.

Authors observed that fake laughter elicit higher pupil dilation than authentic ones. The opposite was observed with cries, genuine ones provoke higher pupil dilation that fake cries.

These consequences are explained by authors in the following way.

We must bear in mind that they work with the ideas that cognitive effort is related to pupil dilation and that is possible that the same happens if we talk about intensity in the listened emotions.

Authors comment that is possible that the reason why obtained results are like this, is that the discriminating authenticity in laughs depends more on cognitive effort than on emotional arousal, whilst in cries, the discrimination of authenticity may depend more on the level of emotional arousal they elicit.

Besides, there are more things that may influence these results. For instance, the fact that a fake laugh is considered a more recent cultural tool from an evolutive point of view, whereas fake cries are thought to have a manipulative role. Plus, genuine crying has a biological function of alarm and provokes an intense emotional response when it is heard.

One of the limitations of this study is that information about pupil dilation may be lost with the blinks. Authors say they will try to improve this in future research.

The most important thing in this experiment, it is that it is confirmed that a pupilar response exists, and thus, a response from the autonomic nervous system, when it comes about distinguish which nonverbal vocalizations are true or faked.

Nevertheless, as this is a novel study, authors point out the need of delve into this topic.

Friends of the Nonverbal Communication Club, this week we present the paper “Sitting in judgment: How Body Posture Influences Deception Detection and Gazing Behavior”, by Zloteanu, M.; Krumhuber, E. G. and Richardson, D. C. (2021), in which authors study whether changing our body posture affects to people’s ability of perceiving and read other one’s behavior.

A very popular field of study within nonverbal communication is deception detection.

Reality is, that even though we think we are good at it, we are pretty clumsy. Our percentage of correct answers in deception detection is only slightly better than predicted by chance. Moreover, we tend to assume most statements people make are honest.

Prior research have demonstrated that changes in posture appear to have systematic and causal effects on how we see the world and how we see ourselves. An example of this would be the “power-posing”, which is worldwide known thanks to some recent studies.

Thus, if there are studies that confirm that maintaining a specific posture can make us feel more self-confident and powerful, is the posture also able of making us better or worse deception detectors?

This is the question that authors want to make clear, and the reason why they think this study is so important.

Postures can transmit lots of information in nonverbal communication, for instance, they can reflect friendliness or unfriendliness. They affect how we are perceived, how we perceive others and how we interpret information. Even effects on cognition and memory have been found in some investigations.

Authors wonder which are the differences that would appear in our deception detection capacity whether if we adopt an open posture or a closed posture when we observe the objective we have to analyze.

But what is an open posture and what is a closed posture?

Traditionally, an open posture has individual sitting with their arms uncrossed and legs uncrossed, in a relaxed recline. Basically, they are expansive physical displays adopted by individuals when feeling relaxed and willing to engage social interaction.

On the other hand, a closed posture typically has individuals sitting with their arms and legs crossed, in a rigid position. It is adopted when feeling threatened, uncomfortable, and, to sum up, signaling a lack of desire to interact.

The hypothesis authors try to confirm with their studies is: if posture influences social acuity, “judges” (these would be the people that have to discover if the other is lying or not) adopting an open posture should attend more to nonverbal information and integrate it more optimally in their veracity judgements compared to the closed posture judges.

Will it happen as authors expect?

In order to answer this question, two studies were carried out. The first of them had the objective of knowing if adopting one or another type of posture affects deception detection judgements. The second one considers the effect of posture on gazing behavior.

Participants of both studies had to watch a total of 12 videos. In 6 of them, a person saying the truth appeared. The opposite happened with the other 6.

Individuals were trained in order to know what microexpressions are, and how to identify and link each one of the basic emotions with some typical microexpressions. Besides, they answered a questionnaire to test their levels of empathy, because as we know, empathy is a very important element if we want to infer emotions.

In the first study, it was found that adopting an open posture resulted in higher discriminability in deception detection, compared to adopting a closed posture. An effect that was more visible with higher levels of empathy.

In the second study, when people adopted open postures, it seems they focused less on the hands of the people. They actually payed less attention to the nonverbal behavior of senders than it was expected.

To explain this last information, authors say that, perhaps, if people adopt an open posture, they are primed to dedicate more resources to processing social information. In this way, posture may be affecting how the judges process information, and not their tendency to inspect their targets more thoroughly.

As is usually happens, there are some limitations in this study. For instance, the inability to measure emotion-specific recognition rates. On the other hand, gender biases were not studied either.

Authors recommend to other researchers that further investigations should correct these mistakes in order to obtain more accurate results. Besides, they point out the need of continuing studying this field of nonverbal behavior.

Because we all want to know when somebody is lying to us, right?

NonVerbal Communication Blog