From Knowable Magazine:
You can’t spot a liar just by looking — but psychologists are zeroing in on methods that might actually work
Police thought that 17-year-old Marty Tankleff seemed too calm after finding his mother stabbed to death and his father mortally bludgeoned in the family’s sprawling Long Island home. Authorities didn’t believe his claims of innocence, and he spent 17 years in prison for the murders.
Yet in another case, detectives thought that 16-year-old Jeffrey Deskovic seemed too distraught and too eager to help detectives after his high school classmate was found strangled. He, too, was judged to be lying and served nearly 16 years for the crime.
One man was not upset enough. The other was too upset. How can such opposite feelings both be telltale clues of hidden guilt?
They’re not, says psychologist Maria Hartwig, a deception researcher at John Jay College of Criminal Justice at the City University of New York. The men, both later exonerated, were victims of a pervasive misconception: that you can spot a liar by the way they act. Across cultures, people believe that behaviors such as averted gaze, fidgeting and stuttering betray deceivers.
In fact, researchers have found little evidence to support this belief despite decades of searching. “One of the problems we face as scholars of lying is that everybody thinks they know how lying works,” says Hartwig, who coauthored a study of nonverbal cues to lying in the Annual Review of Psychology. Such overconfidence has led to serious miscarriages of justice, as Tankleff and Deskovic know all too well. “The mistakes of lie detection are costly to society and people victimized by misjudgments,” says Hartwig. “The stakes are really high.”
Tough to tell
Psychologists have long known how hard it is to spot a liar. In 2003, psychologist Bella DePaulo, now affiliated with the University of California, Santa Barbara, and her colleagues combed through the scientific literature, gathering 116 experiments that compared people’s behavior when lying and when telling the truth. The studies assessed 102 possible nonverbal cues, including averted gaze, blinking, talking louder (a nonverbal cue because it does not depend on the words used), shrugging, shifting posture and movements of the head, hands, arms or legs. None proved reliable indicators of a liar, though a few were weakly correlated, such as dilated pupils and a tiny increase — undetectable to the human ear — in the pitch of the voice.
Three years later, DePaulo and psychologist Charles Bond of Texas Christian University reviewed 206 studies involving 24,483 observers judging the veracity of 6,651 communications by 4,435 individuals. Neither law enforcement experts nor student volunteers were able to pick true from false statements better than 54 percent of the time — just slightly above chance. In individual experiments, accuracy ranged from 31 to 73 percent, with the smaller studies varying more widely. “The impact of luck is apparent in small studies,” Bond says. “In studies of sufficient size, luck evens out.”
This size effect suggests that the greater accuracy reported in some of the experiments may just boil down to chance, says psychologist and applied data analyst Timothy Luke at the University of Gothenburg in Sweden. “If we haven’t found large effects by now,” he says, “it’s probably because they don’t exist.”....
....MUCH MORE
