Can we detect liars?

There is an eloquent comment on the previous post recommending that apprehending pedophiles is “best left to law enforcement.” They’re trained, capable, and importantly, legally authorized.

Law enforcement professionals might be more able to detect when someone is lying, although much more research is needed.

A study posted by the British Psychological Society cited a recent meta-analysis (DePaulo et al., 2003) to make the point that, according to psychological research, there are no reliable cues to deception, and added that other research implies that police officers are not very good at spotting liars. But these studies have been almost wholly based on how Western students behave when deceiving in relatively low-stakes situations.

In a recent examination of forensic psychology published in Applied Cognitive Psychology the participants were experienced police officers. The officers’ task was to judge four sets of clips of liars / truth tellers on four different occasions. Their total accuracy (four tests combined) was 72 per cent. This is an improvement on the usual 50-60 per cent hit rate. Officers were equally good at detecting truth (70 per cent accuracy) and lies (73 per cent).

Yet there’s plenty of evidence that would-be lie catchers often rely on rigid cues, including signs of nervousness, which could be displayed by an innocent person who is anxious about being believed….