Truth or lie - trust your instinct, says research

When it comes to detecting lies, you should trust your instinct, research suggests.

We are better at identifying liars when we rely on initial responses rather than thinking about it, say psychologists.

Generally we are poor at spotting liars - managing only slightly better than flipping a coin.

But our success rate rises when we harness the unconscious mind, according to a report in Psychological Science.

"What interested us about the unconscious mind is that it just might really be the seat of where accurate lie detection lives," said Dr Leanne ten Brinke of the University of California, Berkeley.

"So if our ability to detect lies is not conscious - we simply can't do this when we're thinking hard about it - then maybe it lives somewhere else, and so we thought one possible explanation was the unconscious mind."

When trying to find out if someone is lying, most people rely on cues like someone averting their gaze or appearing nervous.

However, research suggests this is not accurate - people perform at only about 50% accuracy in traditional lie detection tasks.

Psychologists at the University of California were puzzled by this, as some primates, such as chimps, are able to detect deceit - and evolutionary theory supposes that it maximises survival and reproductive success.

Dr Ten Brinke and colleagues devised experiments to test the ability of the unconscious mind to spot a liar, to see if they could do better than the conscious mind.

They gave 72 students videos to watch of "suspects" in a mock crime. Some of the suspects in the videos had stolen a $100 bill from a bookshelf, whereas others had not, but all were told to pretend they had not stolen the money.

When the participants were asked to say who they thought was lying and who was telling the truth, they were able to detect liars only 43% of the time, and truth-tellers only 48% of the time.

Then the researchers used a word association task to test unconscious perception.

The volunteers were asked to look at a picture of the suspect's face and choose which words came to mind from two lists - words such as untruthful and dishonest, or words such as honest and valid.

They performed better, providing evidence that we may have some intuitive sense, outside of conscious awareness, that detects when someone is lying.

This may mean intuitive decisions - such as who to be friends with and who to date - are guided by our unconscious mind telling us someone may be lying, said Dr Ten Brinke.

She added: "It's possible that we make decisions on a daily basis as to who we are going to continue to interact with, so we decide to become friends with some people and not others, to continue dating some people and not others, or to work closely with some and not others.

"Perhaps some of this decision is driven by our intuitive sense that some of these people we choose not to interact with are lying to us."