Scientists say there is evidence that lying is more cognitively demanding than telling the truth.
Detecting lies might seem tough, but often, we catch them almost instinctively. Often, it's the liar's mannerisms—like a shaky voice or an implausible story—that give them away. However, some skilled liars can easily deceive others without detection. Scientists have now discovered a simple yet effective way to detect lies, according to a report from Indy100.
A recent study found that asking someone to perform an additional task during questioning significantly increases the chances of detecting lies. Scientists explain that deceit requires significant mental effort and energy. Experts found that multitasking while lying makes it harder to concoct and sustain a convincing lie, thus aiding in lie detection.
This research was conducted by experts at the University of Portsmouth and was published in the International Journal of Psychology & Behavior Analysis. The experiment consisted of participants telling the truth or lying about some societal issues. A total of 164 people were taken into account and were asked about their level of support for controversial topics in the news at the time, such as immigration, Brexit, and the UK's former Prime Minister Boris Johnson.
The results of the experiment found that the stories of the liars were deemed less plausible than the truth-tellers, and this was mostly visible when the liars were given a secondary task to focus on. Two-thirds of the participants were asked to remember and recall a car registration number during the interview. Half of these participants were told that the secondary task was important, as per IFL Science.
The pre-registered hypothesis test results indicated that there were major differences between truth-tellers and lie-tellers in the condition where they were performing a secondary task with incentives. The experiment was also conducted in a controlled condition, where no secondary task was given, and then in a condition where they performed the secondary task without any incentives.
One of the study’s authors, Professor Aldert Vrij, commented on the result: "The pattern of results suggests that the introduction of secondary tasks in an interview could facilitate lie detection, but such tasks need to be introduced carefully."
Vrij, however, gave a conclusive statement on the experiment as he said, "It seems that a secondary task will only be effective if lie tellers do not neglect it. This can be achieved by either telling interviewees that the secondary task is important, as demonstrated in this experiment, or by introducing a secondary task that cannot be neglected (such as gripping an object, holding an object in the air, or driving a car simulator). Secondary tasks that do not fulfill these criteria are unlikely to facilitate lie detection."