Most of us believe we can tell when someone is lying. We look for shifty eyes, nervous hands or a hesitant voice. Decades of research tell a humbling story: when people judge truth and lies from behaviour alone, they are right only about 54% of the time, barely better than tossing a coin. This applies to the general public and, surprisingly often, to trained professionals too. This article is the first in a short series on deception detection. Here we look at what it is, who

If body language is a poor guide to honesty, what about the words themselves? Statement content analysis starts from a simple idea: describing something you actually lived through tends to produce a different kind of account from describing something you made up.

Lying is mentally demanding. A person who is not telling the truth has to invent a plausible story, remember what they have said, watch the listener's reactions, and control their own behaviour, all at the same time. The cognitive approach to interviewing uses this extra effort to make differences between truthful and deceptive accounts easier to see.

Imagine an investigator who already knows something important, perhaps a phone record or a witness sighting. A common instinct is to reveal it early to see how the person reacts. Research suggests this is often the least useful thing to do. The Strategic Use of Evidence technique, known as SUE, focuses on when and how evidence is introduced.