Scientists have told how to recognize a lie

New study by British scientists from the University of Portsmouth revealedThe effects of a secondary task on true and false opinion statements / International Journal of Psychology & Behavior Analysis an effective method to find out that you are lying. It is enough to give a potential liar an additional task, and it will become much easier to split him.

Thanks to earlier researchThe language of lies: Behavioral and autonomic costs of lying in a native compared to a foreign language / American Psychological Association we know that the brain of a person who lies is loaded more than those who tell the truth. The need to take extra steps hinders the cognitive processes that a person needs to maintain in order to lie convincingly. As a result, the lie is less coherent, and inconsistencies are easy to spot from the outside.

Scientists conducted experiments on 164 volunteers. They were invited to discuss controversial topics like COVID-passports, Brexit and attitudes towards Boris Johnson's politics. At the same time, the participants were randomly divided into those who should tell the truth and lie. The researchers were also divided: one part controlled the conditions of the experiment and distributed volunteers, while the second was required to identify liars, having no supporting information.

So the researchers made it harder for some would-be liars: some were told they'd get a cash prize if they convinced the scientists they weren't lying, others were asked to remember and mention a specific car number during a conversation, and half of them were also told that this task was especially important.

The experiment showed that the lie became less coherent and convincing when the liar had an additional task that he considered especially important. By trying to focus on two things at once, a person cannot lie as plausibly as when given the opportunity to carefully consider the lie. The scientists noted that the additional task should be introduced with caution: if the participant did not consider it important and did not strive to complete it, there was no effect.

A warning that a task is especially important, or the choice of tasks that helped to increase the chances of success, helped could not be ignored (e.g. holding a specific object or using a driving simulator).

In practice, this can be useful for recruiters who will be able to interviews find out if the candidate really fits the position.