The Times has an interesting piece on a police interview technique that asks the suspect to tell the story in reverse order. A recent study has found this makes it more likely that liars will give themselves away.
The research has been conducted by Prof Aldert Vrij and colleagues who specialise in the psychology of police interviews and deception.
The idea behind it is that you have to expend considerable effort when you’re lying not to look stressed and to make sure your story doesn’t contradict itself.
One way of making this less easy, is to put additional strain on your mental resources by asking you to do something more difficult with the story.
This is especially tricky for liars, because for people who are telling the truth, explaining the events in reverse order is less of an effort than for people who are making the story up.
When someone is using their concentration to do this harder task, they will concentrate less on making sure they look comfortable with their story, and so are more likely to let signs of stress slip out.
On the other hand, they may have to concentrate harder on making themselves look relaxed, and make some errors in their story.
This is known as a type of ‘cognitive load‘ interview and is routinely used in police investigations.
It’s not a sure fire way of detecting deception, because liars who are better at concentrating will be less likely to give themselves away, but it seems to increase the chances of the police working out if the suspect is trying to pull the wool over their eyes.
Deception Blog has some more information about the technique, and some links to additional coverage if you want to explore further.