Our unconscious instinct for lies
When we are lied to, we usually don't realise it. However, the body often reacts differently to lies than to the truth. So does it help if you recognise your own body signals particularly well?
Distinguishing between lies and truth is difficult: the judgements of laypeople are generally no better than if you were to flip a coin. But subconsciously, we can obviously guess what is going on. This is because the physical reactions to lies and true statements differ, as a study in the journal "Personality and Individual Differences" shows - we just don't know how to read these subconscious signs.
The well-known lie researcher Leanne ten Brinke from the University of Columbia in Canada was among those involved in the study. She has been searching for several years for evidence that people can unconsciously distinguish between lies and truth. As early as 2019, she reported success and also discovered that people who learn to listen to their own body signals also learn to recognise lies better. Now, together with other colleagues, she wanted to find out whether some people naturally have a keen sense of their body - and therefore also of lies and truth.
A test with real lies and high stakes
To this end, the team first asked around 80 students to repeatedly assess whether a tone sequence followed the same beat as their own heartbeat. How well they succeeded in doing this served as a measure of the accuracy with which they perceived the signals from their own bodies - their interoception. They were then shown a total of 32 videos in which people lied or told the truth. These included contestants on a game show with prize money of 20,000 dollars who claimed that they did not want to cheat on their game partner. On the other hand, they were people who appealed to the public in search of missing relatives, half of whom were later found guilty of killing the missing person. While the test subjects watched the videos, their skin conductance and vascularisation were measured.
They were then asked to make a judgement: Who had lied, who had told the truth? If they had simply guessed, they would have been 50 per cent right. On average, however, the test subjects were around 55 per cent correct, a success rate that corresponds pretty closely to that of older studies. Although there was no evidence of increased skin conductivity in the face of lies, the blood vessels constricted more with lies than with true statements. If they had noticed this reaction and based their judgement on it, the test subjects would have recognised around 68 per cent of the cases correctly.
But this was obviously not the case. Even the test subjects with good interoception were not correct more often. And this was despite the fact that their blood vessel width differed even more in the face of lies and truth: people who react physiologically more strongly to emotional stimuli feel their bodies more accurately. The group suspects that other influences are involved in the judgement because they still do not consciously recognise lies better.
The unconscious perception can manifest itself in other ways, however, as reported by a team led by ten Brinke 2021. According to the study, test subjects reacted with more compassion to the sight of real grief than to feigned grief. The group identified characteristics of grief in facial expressions that were difficult to fake.
The findings of ten Brinke and her colleagues contradict other findings from lie research. They believe it is a misconception that lies are noticeably and systematically reflected in non-verbal behaviour - such evidence is usually only very weak and unreliable.
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Cover image: © Motortion / Getty Images / iStock (detail). Sometimes your gut feeling tells you that the person you're talking to has something to hide. (symbolic image)
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