The New Mental Trick That Could Reliably Help You Spot Liars

Liars were identified 81 percent of the time.

Posted Dec 05, 2020

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The emerging field of "load-inducing" lie detection is referred to by some experts (Walczyk et al., 2013) as "lie detection by inducing cognitive load selectively on liars."

Accumulating evidence suggests that giving someone a simple set of instructions that increase cognitive load before conducting a lie-detecting interview can alter the narrative strategy of both truth-tellers and liars.

A new cognitive load lie-detection method making headlines this month is called the "asymmetric information management" (AIM) technique. A recent Journal of Applied Research in Memory and Cognition paper (Porter et al., 2020) puts AIM in the spotlight. Cody Porter of the University of Portsmouth's Institute of Criminal Justice Studies is the paper's first author.

In a December 3 article for The Conversation, Porter describes her motivations for developing the AIM technique. "Unfortunately, it is difficult to detect lies accurately. Lie detectors, such as polygraphs, which work by measuring the level of anxiety in a subject while they answer questions, are considered 'theoretically weak' and of dubious reliability," she writes.

"Our technique is part of a new generation of cognitive-based lie-detection methods that are being increasingly researched and developed," Porter explains. "These approaches postulate that the mental and strategic processes adopted by truth-tellers during interviews differ significantly from those of liars. By using specific techniques, these differences can be amplified and detected."

AIM increases a subject's cognitive load by informing potential truth-tellers or liars at the beginning of an interview that "more detailed statements are easier to accurately classify as genuine or fabricated" and encouraging people to be verbally forthcoming with small details. These instructions tend to trigger a knee-jerk reaction in liars that makes them want to withhold information and keep their answers short.

"Specifically, interviewers make it clear to interviewees that if they provide longer, more detailed statements about the event of interest, then the investigator will be better able to detect if they are telling the truth or lying," Porters said. "For truth-tellers, this is good news. For liars, this is less good news."

To test the AIM technique's effectiveness, Porter and colleagues recruited 104 study participants at a university and sent them on a "covert mission" that involved retrieving and/or depositing intelligence material somewhere on campus.

After the mission was completed, participants were randomly assigned to one of two different groups: "truth-tellers" (n = 52) or "liars" (n = 52). Then, as part of a preplanned script, each person was fictitiously told that there'd been a data breach, which required them to sit for a fact-gathering interview.

Those assigned to be "truth-tellers" were instructed, "to tell the truth about their mission to convince the interviewer of their innocence." Conversely, those in the "liars" group were instructed, "not to disclose any information about their mission and to come up with a cover story about where they had been at the time and place of the breach to convince the analyst of their innocence."

During their lie-detection interviews, the AIM technique was used with half (26) participants in each 52-person group. Porter and colleagues found that the AIM technique made it significantly easier to spot liars. When using AIM, lie-detection accuracy rates were 81 percent compared to 48 percent when AIM wasn't used.

"Truth-tellers provided (and liars withheld) more information in the AIM condition (compared to the control condition), and thus, discriminant analysis classificatory performance was improved," Porter concludes. 

The latest (2020) lie-detection research suggests that simple AIM-based instructions can simultaneously modify the interview strategy of both liars and truth-tellers in ways that reveal who's telling the truth and who's not.


Cody Normitt Porter, Ed Morrison, Ryan J. Fitzgerald, Rachel Taylor, Adam Charles Harvey. "Lie-detection by Strategy Manipulation: Developing an Asymmetric Information Management (AIM) Technique." Journal of Applied Research in Memory and Cognition (First available online: March 20, 2020) DOI: 10.1016/j.jarmac.2020.01.004