How do you catch a liar?


  • In order for the respondent to take the additional instruction or task seriously, they must be told it is important or given a task they cannot neglect, e.g. B. grab an object, hold an object in the air or drive a car simulator.

“There is evidence that lying is more cognitively demanding than telling the truth.” said scientists from the University of Portsmouth in the UK and Florida in the US. In a recent study, they showed that recruiters who used this insight to their advantage by asking the candidate to do an extra task during the interview were more likely to catch liars.

An experiment conducted with 164 people

Published in the journal as part of her work International Journal of Psychology and Behavior Analysisthe authors wanted to examine how performing a side quest affects the arguments of people who tell the truth and those who lie. To do this, they recruited 164 people who asked them to put themselves in the conditions of an interview. Some had to tell the truth and others had to lie when answering questions about social issues.

Two-thirds of the participants were also asked to recall and retrieve a car’s license plate number during the interview. For a third of the participants this additional instruction was made important. “The variables considered were the number of words spoken and the number of arguments presented, as well as the plausibility, directness and clarity of the statement”, we can read in the study.

“The introduction of an additional task has made lie detection easier”

According to the results, recruiters who asked a candidate for an additional task during the interview were more likely to detect liars. According to the researchers, the extra brain power required to focus on a secondary instruction or task (other than lying) was particularly difficult for people who lied.

“Introducing an additional task or instruction during the interview made it easier to detect lies. It seems that a secondary task is effective only if the liars do not neglect it,” said the scientists.

Leave a Comment