People are extremely bad at spotting lies. According to Sophie Van der Zee, associate professor at Erasmus School of Economics, you can just as easily take a gamble. It's almost the same. Scientific lie detection is much more successful in this, but many people still remain sceptical. In an interview by VPRO programme Argos, Van der Zee explains how scientific research enables you to detect lies better than people do.
Motion-capture
Van der Zee developed an experimental method with which she could measure non-verbal behaviour, also known as motion-capture. ‘There was this common idea that non-verbal behaviour was not a good indication of lying,' says Van der Zee. ‘I thought: wait a minute, you have never investigated this properly! Because how do you determine non-verbal behaviour? By recording a video and then manually counting it behind a computer? That way you can never include all kinds of information.
To test this theory, her team attached sensors to the bodies of test subjects that registered how many millimetres or centimetres they moved per second. Ninety test subjects were then divided into two groups: liars and truth-tellers. The results showed that you move more when you lie than when you tell the truth. ‘We also saw that you can increase this effect by applying certain interview techniques, such as asking someone to tell their story in reverse order,' says Van der Zee.
Ethical issues
‘Every experiment I have ever done has shown that technology performs better at lie detection than people.’ However, Van der Zee is aware of the complicated, ethical aspects of lie detection. Moreover, the technology is not perfect. ‘The moment you are caught, there are all kinds of alternative possibilities. Maybe you have a fever, you have just been running or you are standing next to your boss with whom you are in love. There are millions of reasons for giving signals that will be picked up as lies by such a robot. But then comes the next step: a person who asks good questions to find out exactly what is going on.
Nevertheless, Van der Zee thinks the scientific results are promising enough to carry out field experiments. It is ultimately up to politicians to weigh up the ethical objections against the social usefulness of lie detection technology.
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The full article from VPRO Argos, 17 September 2021, can be found here (in Dutch).