Can police officers really detect lies?

You are grabbed by a bombardment of police officers, immediately your hands are forced behind your back as the steel shackles are thrown around your wrists. They’ve got the wrong person! You are no criminal!

After a short journey escorted by a platoon of police cars, officers and sniffer dogs you arrive at the station. You are now being investigated in police custody…I bet you hope the detectives know you aren’t lying when you proclaim your innocence.

Sound like a scary story? A study conducted by Mann et al aimed at discovering how effective police officers are at distinguishing lies from truths.

The participants were 99 police officers with an average age of 34. The officers were shown 54 video clips of 14 suspects.

The videos were of real police interviews and showed the suspects head and torso to ensure the officers could read both body language and vocalisations of the suspects.

After each clip the officer were asked to say if they thought the suspect was lying or telling the truth and how confident they were in their response. They were also asked to list the cues that brought them to their decision

66 per cent of the time the officers accurately detected suspects telling the truth and 64 per cent of the time officers accurately detected lies.

Mann et al found that the more experienced an officer was the better they were at detecting lies. He also found that officers who were better at detecting lies did so by following the story suspects gave them, rather than the suspects’ body language.

The research did show, however, that gaze was the most commonly detected feature of a lie.

It was concluded that the officers’ ability to detect lies and truths were greater than chance.

 

Picture: Donnie Nunley