There have been a few posts on the forum about lying and deception, and new research adds a new weapon to the arsenal to catch liars in deception.
There is perhaps nothing more that grips the public mind than the allure of possible signs to catch out a liar. But there is now a new tool in the arsenal to detect liars, and it relies upon the difficulty to maintain the ability to deceive and completion of a secondary task.
One of my favourite authors Aldert Vrij from the University of Portsmouth devised an experiment that exploits this difficulty.
It is well known that lying utilises a heavier cognitive load than truth-telling.
How the experiment was done:
164 participants were asked to assess various topics of society in the news and give their personal levels of support or opposition to these. They were then randomly assigned to either a truth group or a lie group. In the truth group, they were told to actually express the truth of their opinions and the opposite in the lying condition.
There was some incentivisation and a prize draw that provided a possible reward to come over as convincing as possible. The groups were given a seven-digit car registration plate to remember and provide as they discussed their opinions.
The liars were much less convincing when attempting to do both tasks, the recall of the license plate and the discussion of their opinions. However, this was only effective if the individuals were told that the secondary task was important.
As Professor Vrij summarised:
“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 into the air, or driving a car simulator). Secondary tasks that do not fulfill these criteria are unlikely to facilitate lie detection."
The University of Portsmouth. "Exposing liars by distraction: A new method of lie detection shows those lie tellers who are made to multi-task while being interviewed are easier to spot." ScienceDaily. ScienceDaily, 10 May 2022. <www.sciencedaily.com/releases/2022/05/220510151446.htm>.