THE PSYCHOLOGY OF CRIMELie detection
Most of us are poor lie detectors. In a meta-analysis of 206 studies
involving over twenty-four thousand people acting as lie detectors,
Charles Bond Jr and Bella DePaulo at Harvard University found that, on
average, people were able to correctly identify just 47 percent of lies as
lies and 61 percent of truths as truths. There’s some evidence that police
officers fare better, but not hugely. Using clips of real suspect-interviews
in a 2006 study, Albert Vrij at the University of Portsmouth found that
police officers correctly identified truthful utterances 70 percent of the
time and lies on 73 percent of occasions. Seven out of ten might not
sound too bad, but extrapolated to real life, it means a lot of innocent
people being wrongly perceived as liars.
Part of the reason we’re so poor at detecting lies is that the folk
wisdom on this issue is so deeply ingrained. We grow up learning from
our parents and from literature and films that liars fidget and avoid
eye-contact. Even influential police-training manuals such as Criminal
Interrogation and Confessions (1986) propagate this myth, highlighting
shifts in posture or nervous gestures as signs of lying. In fact these signs
are most likely to reflect nerves, maybe because of the situation or simply
the person’s disposition. An innocent person who fears being falsely
accused is just as likely to fidget with anxiety as a lying criminal. In fact,
the experienced criminal might well have learned to keep still and main-
tain eye-contact, just so as to come across as telling the truth.
The latest findings in criminal neuroscience
In 2009 in Italy, Abdelmalek Bayout had his murder sentence reduced
by a year on appeal after his defence persuaded the judge that he
had violent genes, including a low-activity version of the MAOA gene
(see p.255). In the same year, in the USA, fMRI brain-imaging evidence
was admitted in court for the first time, as the defence attorneys of
serial killer Brian Dugan attempted to provide evidence that their
client had the brain of a psychopath and could not therefore control
his violent nature. In 2010, a lawyer in Brooklyn successfully sought to
present fMRI evidence to show that a key witness in a civil employer-
retaliation suit was telling the truth. The evidence was disallowed on
the basis that it’s up to the jury, not a fancy brain scanner, to determine
who’s telling lies, but it’s surely just a matter of time before fMRI-based
lie detection reaches the courts.