Words Show Lies

We humans communicate a great deal via our facial expressions and body language. While I usually assume that most such behavior is adaptive – evolved in detail to achieve important ends, some argue that much of this in unwanted leakage – that such expressions reveal stuff about ourselves often against our interests. Studies of liars, however, suggest that there is much less unwanted leakage than most people think:

Contrary to popular belief, liars don’t readily give themselves away with their facial expressions or body language and most of us are easily duped by a determined liar. … When [researchers] pulled together the findings of more than 100 studies looking for cues to deception, they found none that consistently stood out. … “There are no behaviours that always occur when people are lying and never occur when they are telling the truth,” … The idea that liars leak information about their true emotional state through so-called “micro-expressions” is not very helpful either. … “What makes the expert [lie detector] an expert isn’t the ability to watch non-verbal behaviour,” he says, “it’s the ability to ask the right question.” (more)

So why are we more overconfident in our ability to read non-verbal than verbal clues? Is it more important for us to believe in our covert homo hypocritus skills than our overt talking and thinking skills? Some ways that help to detect liars:

If possible, you should compare your suspect’s behaviour under interrogation with a similar situation in the past when you know they were telling the truth. …

Lying is more cognitively demanding than telling the truth, so the alternative strategy aims to exacerbate cognitive differences between liars and non-liars. “It’s almost impossible to ask questions that will make the liar more nervous than the truth-teller, … whereas it is possible to ask questions that are more difficult for a liar to answer.”

One way to do this is to ask your suspect to tell their story in reverse. … Another is to ask for a drawing of the scene in question. … Or you could draw the person out on details of timing. …
A particularly effective line of questioning to find out a person’s true opinion … [is] ask them to argue in favour of their professed position, then to play the devil’s advocate and argue against it. … People are usually able to present more and stronger arguments to support their real opinion than one they have fabricated … By asking a suspected liar to maintain eye contact, you can increase the cognitive load. …

Strategic use of evidence … Instead of revealing everything they knew immediately, they waited for Skuggan to dissemble during questioning and then confronted him with their evidence. … Skuggan tried to play them at their own game, offering details they didn’t have, and that he couldn’t have known if he were innocent. …

Other psychologists are not convinced that we should downplay the role of emotional cues. … Soon-to-be-published research … used “family pleader” videos – televised pleas for information made by individuals whose relative or spouse has gone missing – where there was reliable, independent information about whether the pleader was responsible for the disappearance of the missing person or not. When people trained to look for both verbal and non-verbal cues scrutinised around 80 such videos, they managed to distinguish the liars from the truth-tellers with more than 90 per cent accuracy. Among the giveaways was the tendency for liars to use a tentative word such as “if” where a truth-teller would use a more concrete one such as “when”. Liars also displayed brief expressions of surprise on their upper face – which is what happens when a person tries and fails to look distressed. (more)