An angel's face is still, goes the saying, because there are no lies inside. Now scientists have revealed there is scientific truth behind the notion.
Researchers have established for the first time that five tell-tale facial muscle groups, including those activated by grief, behave differently in people who are lying.
Psychologists examined the facial movements of 52 people who had appeared on television in a number of countries, including the UK, to appeal for the return of someone who was missing. In half the cases analysed they were lying, and were later convicted of murder. The researchers found that the stress of dealing with so-called high-stakes lies meant they were unable to control some muscle movements.
The videos of 26 liars and 26 genuine people who made televised pleas for the safe return or information leading to an arrest in the murder of their relative were gathered from news agencies in Australia, Canada, the UK and the US. The liars had all been convicted eventually on overwhelming physical evidence, including DNA.
The researchers, from the University of British Columbia, analysed more than 20,000 frames of the appearances and found marked differences between the two groups.
They homed in on when the interviewee made a direct appeal to the (supposed) perpetrator to release the missing person; to the missing person to make contact, or to the public for information. Then they focused on muscles associated with sadness, happiness and surprise – the frontalis, corrugator supercilii, orbicularis oculi, zygomatic major and depressor anguli oris.
Their results showed that the "grief" muscles – the corrugator supercilii and depressor anguli oris – were more often contracted in the faces of people who were genuine. The liars were more likely to show subtle contraction of the zygomatic major – masking smiles – and full contraction of the frontalis, frowning – in a sign of failed attempts to appear sad.
In cases in the UK include Tracie Andrews, above, 27, who stabbed her fiancé, Lee Harvey, to death during an argument in their car near Alvechurch, Worcester in 1996. She subsequently appeared in a televised press conference, with Harvey's mother, in which she claimed he was killed by a man in a road-rage attack. Andrews was sentenced to life imprisonment at Birmingham Crown Court in July 1997.
John Tanner, Paul Dyson, Fadi Nasri and Gordon Wardell all made similar appeals, lying to the cameras after killing their partners or having them killed. They were all found subsequently found guilty and jailed.
The study – "Darwin the detective: Observable facial muscle contractions reveal emotional high-stakes lies" – concludes that there is an evolutionary component to lying, and people lie on average twice a day. "While interpersonal deception often is highly successful, signs of covert emotional states are communicated clearly to the informed observer," the researchers said. "The present study investigated, for the first time, the action of specific facial muscles speculated to reveal falsified sadness on the faces of individuals deceptively pleading for the return of a missing relative who they recently had murdered.''
In its paper, published last week, the team concluded: "Our findings support the notion that the human face is indelibly stamped with the tale of our humble origin and attempts to mask our emotions are likely to fail when engaging in a consequential act of deception.''
Additional reporting Koos Couvée