Spotting liars is hard – but our new method is effective and ethical

Most people lie occasionally. The lies are often trivial and essentially inconsequential – such as pretending to like a tasteless gift. But in other contexts, deception is more serious and can have harmful effects on criminal justice. From a societal perspective, such lying is better detected than ignored and tolerated.

 

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. This is because, as any traveller who has been questioned by customs officials knows, it’s possible to be anxious without being guilty.

 

We have developed a new approach to spot liars based on interviewing technique and psychological manipulation, with results just published in the Journal of Applied Research in Memory and Cognition.

 

Our technique is part of a new generation of cognitive-based lie-detection methods that are being increasingly researched and developed. 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.

 

One such approach is the Asymmetric Information Management (AIM) technique. At its core, it is designed to provide suspects with a clear means to demonstrate their innocence or guilt to investigators by providing detailed information. Small details are the lifeblood of forensic investigations and can provide investigators with facts to check and witnesses to question. Importantly, longer, more detailed statements typically contain more clues to a deception than short statements.

 

Essentially, the AIM method involves informing suspects of these facts. 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. For truth-tellers, this is good news. For liars, this is less good news.

 

Indeed, research shows that when suspects are provided with these instructions, they behave differently depending on whether they are telling the truth or not. Truth-tellers typically seek to demonstrate their innocence and commonly provide more detailed information in response to such instructions.

 

In contrast, liars wish to conceal their guilt. This means they are more likely to strategically withhold information in response to the AIM instructions. Their (totally correct) assumption here is that providing more information will make it easier for the investigator to detect their lie, so instead, they provide less information.

original article.