How detectives and intelligence officers can tell if someone is lying.

Deceptive people generally want to say as little as they can, psychological research into lying finds.

Instead of trying to tell an elaborate story, they actually clam up, on the basis that lies should be kept as simple as possible.

Psychologists recommend that detectives and intelligence officers encourage their suspects to talk.

This is just one of the findings of a review of 60 studies on deception carried out by Professor R. Edward Geiselman and colleagues.

Professor Geiselman has taught interviewing techniques to the FBI, Marines, police and sheriff’s departments, along with intelligence officers and others.

Another sign that someone is lying, the research shows, is that deceptive people offer explanations without being asked.

Here are six more of the red flags Professor Geiselman and colleagues have identified:

• Deceptive people sometimes repeat questions before answering them — maybe to buy time.
• They will watch carefully for your reaction to see if you are buying it.
• Deceptive people change the pace of their speech, whereas, “Truthful people will not dramatically alter their speech rate within a single sentence,” Professor Geiselman said.
• Potential body language tells of liars include pressing their lips together and/or playing with hair or gesturing towards themselves (rather than away, which is a sign of truthfulness).
• Liars try to avoid specifics when pushed — truthful people provide more specifics.
• Truthful people often look away to concentrate on their answers — liars stare at you.

Professor Geiselman said:

“People can learn to perform better at detecting deception.

However, police departments usually do not provide more than a day of training for their detectives, if that, and the available research shows that you can’t improve much in just a day.”

Gut reactions should not be relied on, said Professor Geiselman:

“Without training, many people think they can detect deception, but their perceptions are unrelated to their actual ability.

Quick, inadequate training sessions lead people to over-analyze and to do worse than if they go with their gut reactions.”

The study was published in The American Journal of Forensic Psychiatry (Geiselman et al., 2011).