Backward stories for the truth

A cunning new method of dragging the truth from criminals may be on the horizon, thanks to research by university psychologists.

Researchers from the University of Portsmouth claim that the best way to spot a lie is to make the suspect repeat his or her version of events in reverse order.

In a £136,000 project, the researchers worked on the theory that it takes more effort to make up a story than it does to tell the truth. A subject asked to repeat a concocted series of events in reverse order would be under too much of a strain, they claimed, and would make mistakes.

Detectives use many psychological tricks to trip up liars. These betray obvious signals from shifting uncomfortably in a seat, through stumbling over words to failing to make eye contact.

Another interview strategy used, the baseline method, requires investigators to note the way a suspect reacts to small talk before an interview compared with how he reacts to penetrating questions.

Finally there is the behavioural analysis strategy (BAI), in which interviewers compare the body language of liars and those telling the truth to set a list of questions.

Researchers asked 290 police officers to examine the interviews of 255 students who were given true and false details to use in their answers.