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Expert: There are no behaviours that clearly point to a lie

29.07.2017 Society

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There is no such thing as "Pinocchio's nose", a hint that only appears when someone is lying. We can detect lies by means of technologies such as traditional variographer, EEG or... thermal imaging cameras. Dr. Karolina Dukała from the Institute of Psychology at the Jagiellonian University spoke with PAP about the detection of lies and interrogation methods.

PAP: Is it possible to recognize someone that is lying from a distance, based on that person's behaviour?


Karolina Dukała: After the fact - of course! Once we know that someone was lying, it is easy to read signs of lying from that person's behaviour. The basic problem with behaviour-based lie detection methods, however, is that they work post factum. On the other hand, when the thing is happening - for example, when we see a political giving a statement on TV - it is difficult to determine whether he is lying or not.


There is no such thing as "Pinocchio's nose", there is no hint that only appears when someone is lying. The only thing that we can talk about is a degree of these hints. If someone has a very stiff posture - there is a certain probability that the person is lying. If that person also does not make any hand movements - the probability is even greater. If on top of that the person has a fake smile - we are probably on the right track. But this is still only a probability, because people are different. Some, for example, do not move at all when speaking - which in their case does not mean they are lying. And that's exactly why behavioural cues can be misleading.


PAP: And which of the popular "signs of lies" really do not make sense?


K.D.: Probably the most popular myth about the "signs" of lies is looking one way. Meanwhile, there were numerous studies - dozens really - which checked whether liars really looked one way. These studies have proven that it was not true. The assumption that our brain is structured in such a way that we look in one particular direction when we lie, is wrong. The second common myth is touching the nose. On the internet you can find information that when someone touches his or her nose, he or she probably lies - the is definitely false.


Recently there is also a lot of talk about illustrative gestures. This means gesticulation that emphasises the statement. For example, if someone tells you that they saw something big - they automatically make a gesture to show how big that thing was. It was thought for a long time that these gestures are correlated with the truth: if someone uses them, that person probably tells the truth. However, recent research, especially the 2016 meta-analysis of the issue, shows that we attached too much importance to these gestures - they are not such a good indicator of lies.


PAP: Does that mean that we are seeing the departure from lie detection methods based on observation?


K.D.: It is not that observation-based methods are disappearing! For prosecutors and policemen, they are still everyday tools. We should remember that in Poland the Code of Criminal Procedure prohibits the use of evidence obtained through methods that "exclude consciousness" and do not give the person concerned the possibility of defence - so it is controversial to use a polygraph, a "lie detector", called a variograph in Poland. As a result, investigators continue to rely on the observation of verbal and nonverbal behaviour of the interrogation person. They pay attention to the intensity of the cues that have already been mentioned: the suspect's gestures, the pace at which they speak, pauses in speech, the choice of words.


At the same time, however, these methods are least effective: according to research, their accuracy varies between 60 and 65 percent. Their popularity is primarily due to accessibility - although training in these methods is often based on outdated knowledge.


PAP: Well, but since it is difficult to detect lies "on sight" - what other methods are available nowadays?


K.D.: Of course we have the polygraph, one of the oldest devices for detecting lies. Recently, the idea to use... thermal imaging cameras for this purpose was patented in the US. There is also an EEG test - although it is quite cumbersome during an interrogation, because the suspect has to have a lot of electrodes attached to the head and only strictly defined questions can be asked. In countries where this method can be used for interrogation, it is solved in such a way that the EEG expert enters only after completing the main part of the interrogation and asks specific sets of questions, among which key are, for example, "Was the victim killed with a knife?".


I would also like to mention my favourite, the AVATAR - the American idea for low cost screening and detection of, for example, terrorists at airports. It has the shape of a standalone booth, which a person enters and then the booth asks question that the suspected person must answer. The booth is equipped with a thermal imaging camera, voice analyser, eyetracker, pulse measuring device - all sorts of lie detectors. This is a comprehensive package of everything that has been developed in this area so far.


PAP: In you research work, including the National Science Centre Prelude grant, for a long time you have been dealing with a very specific subject: the methods of interrogating older people. I am curious - should seniors really be interrogated differently than younger people?


K.D.: The elderly not only think differently but also have different cognitive processes. They have problems with attention, they stay focused for much shorter periods than younger people, they are less patient, and their memory functions differently. Seniors need a lot more guidance from the interrogator - that's why it is important to use alternate methods of interrogation.


For example, it is not that seniors remember much less. Yes, their attention is not as good as the attention of young people, they notice less, so they also recall less. But what they do remember - they are able to recall really well and accurately. You just have to have the right tactics to conduct the interview properly.


There are many ideas how to interrogate seniors. It seems to me that the best method, most thoroughly tested in practice, is the so-called cognitive interview. This is a special type of questioning in which questions are asked in such a way as to entice the interrogated person to recall details that may appear irrelevant. It makes it easier for the interviewee to think, to remember things. When a person is stressed out or upset, he or she is more focused on emotions than on thinking. The cognitive interview is designed to suppress such emotions. Cognitive interview also includes various specific techniques, such as "Tell everything again but from the end" or "Tell everything again but from a different perspective". Although they seem naive, scientific research has shown that such techniques greatly increase the amount of detail that a witness of a crime can give.


PAP - Science and Scholarship in Poland, Katarzyna Florencka


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