London, April 15: A new way of spotting a liar has been devised by a psychologist who has discovered that it takes longer to tell a lie than it does to tell the truth.

Aiden Gregg said that his method, tested on Christian men and women, proved to be more than 85 per cent accurate and could be adapted for the police. It could also be used to support polygraph lie detectors, not used in Britain because of their inaccuracies.

Gregg, a research fellow at the centre for research on self and identity at Southampton University, found that when people were instructed to answer true and false statements about themselves dishonestly and statements about the world honestly, they took significantly longer on the task than people who told the truth. They were compared with Christians who were allowed to answer both types honestly. Those who answered honestly were quicker. The difference between the two groups was between half a second and one second.

The subjects were asked to answer the questions by pressing keys as quickly as they could. Personal questions put to the subjects included statements such as “I am a believer” and “God exists” as well as “I am an atheist” and “There is no supreme being”. The “world” questions included “Grass is green”, “Earth is round”, “Tigers have stripes”, “Grass is blue”, “The Earth is square” and “Tigers have spots”.