The Psychology of Lies: Behavioural Science Perspectives on Conducting Successful Interviews

There are plenty of myths about the “science” of lie detection despite what books on nonverbal behaviour may say. There is no scientific evidence that crossed arms or legs indicate a defensive person, or that deceivers touch their noses, Evert their eyes, or cover their mouths. Spotting a lie is an inexact science.

Can investigators improve their chances of discovering deceit during investigative interviews?

Why Humans Are Good Deceivers and Lousy Detectors

Humans are better liars than they are lie detectors. This point is evidenced in various academic studies, which suggest that most people are no better than 50/50 at detecting deception by observing verbal and nonverbal cues. Even professionals involved in fighting crime such as law-enforcement fair only a little better than chance at detecting a lie. In essence even if law enforcement as a whole was better at detecting deception than the general public, that isn’t a particularly impressive statistic.

Most people are no better than 50/50 at detecting deception by observing verbal and nonverbal cues. But there’s hope yet for lie detection science.

Many previous experiments are based on low-stakes lies. In the real world, lies that concern investigators or potential employers are usually high stakes—in other words, liars in the interrogation room have a lot more to lose than study participants.

As anxiety lies at the root of high-stake lies—if unmasked, the deceiver faces stiff consequences. But the researcher’s dilemma is that high-stakes lies—and the anxiety associated with them—are hard to ethically replicate in a laboratory.

How to be a Good Liar

Naturally, some people are bad liars; but professional investigators are concerned with the gifted ones. It stands to reason that to be a good lie spotter; the investigator needs to know what makes a good liar. Sometimes the investigator may need to be good a liar himself in order to go undercover or pretext.

Accordingly good liars are ultimately good actors. So how to lie convincingly is to “rehearse” in order to reduce anxiety; by creating plausible responses by interweaving deception with truth. In theory then good lying, like good acting, is an art that requires a plausible story, well-practiced.

There are, however, pathological types that make natural liars: psychopaths and pathological liars such as those suffering from Munchausen syndrome. Pathological liars may tell lies with ease, but they are usually unmasked over time by inconsistencies.

Psychopaths, on the other hand, are natural chameleons that mimic the behaviour expected of them but have little or no emotional attachment. In essence, psychopaths have little fear or anxiety but are natural actors. A “lack of stress” enables them as deceivers.

Like the psychopath that simulates love for another when it serves him, good liars uses a measure of control over emotional appearances to overcome discovery. The possibility that a liar will be unmasked naturally creates the desire to avoid the issue, but a savvy liar can take the offensive.

For instance, he may mimic anger or hurt in response to an accusation that’s true. The seeming natural response would be anxiety or embarrassment, but a good liar can turn the tables, emotionally speaking.

A final quality of good liars is self-deception. Self-deception reduces anxiety by justifying the lie.

Catching Liars through Cognitive Taxation

The idea here is that lying requires extra psychological effort at creating a plausible story, whereas the truth doesn’t, because the teller is simply recalling, not inventing. An interviewer can exploit this fact through several strategies (as summarized below):

1. Ask for details.

The more details the interviewee provides the more chance of inconsistency. This fact alone may cause the guilty interviewee to be reluctant about answering questions or to give short or vague responses. If the interviewee is reluctant or vague in responding to a question, the interviewer should pursue the subject further.

Borrow from the techniques of “cognitive interviewing”—developed to enhance eyewitness’ memories—because they are useful in encouraging the subject to report details. Such techniques include asking the subject to describe his story with richness and imagery and to reassure him that no detail is without significance or is too trivial.

While inconsistency, vagueness and hesitancy can be signs of deception, details provide the practicality of more information that can be cross-referenced and validated.

2. Ask unexpected questions.

Just as the would-be-liar rehearses responses to anticipated and expected tough questions, the interviewer should try asking “unexpected questions” as a counter-measure. To be successful, the interviewer must be able to develop relevant questions that the interviewee doesn’t anticipate. Liars produce fewer details when responding to unanticipated questions than truth-tellers.

3. Conduct an information-seeking interview rather than a confrontational interview.

Law enforcement methodology is to progress from interview through to accusation. Basically, this is a presumption of guilt from the outset that incrementally increases pressure on the subject to make a confession.

In contrast the information-seeking interview is one in which the interviewer aims to build rapport and plays a sympathetic role in order to coax out facts. Information-seeking approaches yield more information and cues to deceit than confrontational approaches.

4. Strategic Use of Evidence

The non-accusatorial interview is the asking of open-ended questions and presenting evidence late in the interview. This does reveal more inconsistencies and contradictions than when any evidence is introduced early.

Furthermore, when the interviewer asks formulated indirect questions specific to the evidence without revealing the interviewers own knowledge of that evidence, the ability to detect deception significantly increases. (Such questions are also introduced at a late stage in the interview.)

Catching Liars through Emotional Leakage

Micro-expressions betray a person’s true feelings, but you almost need a video camera running in slow motion to see them although a person can either be trained to see them in real time or be very experienced through conducting many interviews.

Unfortunately individuals have different baseline behaviours and different levels of response. For instance, one person may be naturally anxious in most situations, while another may become anxious when asked questions that he believes may falsely incriminate him. There are also liars who show little anxiety because they are well rehearsed in their deceit, are self-deceived, or suffer pathological conditions.

A guilty person facing the possibility of unmasking should be anxious, but so, too, could an innocent person in fear for his freedom…remember that there are exceptions to every rule.

Parting Wisdom

Unfortunately, a popular belief on nonverbal behaviour and lie detection has managed to leak into texts on police interviewing and interrogations.

Nonetheless, behavioural science is making headway, and investigators should pay attention. An interview with a suspect relies on a psychological strategizing that aims to unmask the truth. Deceit betrays itself by behavioural and narrative inconsistencies.

Looking for incongruences in a subject’s story and behaviour is common sense, but investigators can improve their chances of discovering lies by aligning their strategies with advances from the behavioural sciences. Watching for involuntary micro-expressions and the theory of cognitive load are two such advances that can aid an investigator’s tactics and observations.

The investigator must consider all possibilities when interpreting the significance of a statement, pause, contradiction, gesture or hesitation. The goal shouldn’t be to become a psychological X-ray machine, because that’s currently impossible.

Instead, the investigator should aim to acquire verifiable intelligence, and/or, if the intelligence merits it, a true confession.

Frank Nesbitt MA MEWI