Right questions could help spot devious air passengers

Airport security agents can better detect liars with a few detail-oriented queries

people waiting in line to board plane

SAFER SKIES  Asking airplane passengers probing questions about particular details of their lives may help unmask liars.


A new interview method that probes for detail shows promise as a way to identify many more airplane passengers who are lying about their backgrounds than current security measures do.

Security agents using the new approach at European airports pegged 66 percent of passengers who had been coached and paid to lie about their backgrounds before boarding international flights, say British psychologists Thomas Ormerod of the University of Sussex and Coral Dando of the University of Wolverhampton. In contrast, security agents using the standard method — scripted questions to probe for signs of nervousness or other suspicious behaviors — identified about 5 percent of deceptive passengers, the investigators report November 3 in the Journal of Experimental Psychology: General.

“We think airport security can be improved by questioning the veracity of what passengers say about themselves rather than searching for suspicious behaviors,” Ormerod says.

Evidence in favor of screening passengers by first looking for individuals who appear nervous or suspicious is weak, says psychologist Maria Hartwig of the City University of New York. That’s the usual practice at European and U.S. airports. Suspicious-looking behaviors, such as avoiding eye contact, can reflect shyness or other factors that have nothing to do with lying.

Some studies indicate that a questioner can often tell deceivers from truth-tellers by probing details of a person’s story. If someone claims to have studied at the University of Oxford, for instance, an interviewer could ask how to travel on public transport from the train station to the university. After a few such questions, liars tend to become less talkative and informative than truth-tellers.

Ormerod and Dando developed a security screening method based on those findings. The researchers randomly assigned 79 of 162 security agents from seven major European airports to one week of classroom instruction and one week of on-the-job training in knowledge-challenging interview techniques. All but two agents passed the course.

Those who passed spent eight months in 2013 using the technique to interview passengers on international flights. The other 83 agents relied on standard interviews focused on suspicious behaviors. Each interview lasted an average of about three minutes, regardless of method.

During the trial, 204 mock passengers recruited by the scientists showed up at the various airports. Each volunteer received the equivalent of about $95 for participating. That amount doubled if they could fool a security agent with a deceptive story about their background, provided by the researchers. Mock passengers had one week to gather supporting information for their assigned stories and practice talking about their fake backgrounds with an experimenter.

Audio recordings of agents’ interviews with mock passengers were compared with interviews of 204 actual passengers matched for age, sex, nationality and native language.

Agents identified a fraction of 1 percent of actual passengers as deceptive in the six months before the trial and during the trial, regardless of interview technique. The researchers don’t know how many of those passengers were actually lying.

Agents using the new interview technique detected a majority of paid liars despite encountering only one mock passenger for every 1,000 genuine passengers. Those relying on the standard method saw reason to stop only 10 mock passengers.

Ormerod and Dando’s study represents a step forward in designing security interviews, says psychologist Mark Frank of the University at Buffalo in New York. But there’s no way to determine from audio recordings whether nonverbal behaviors helped to undermine mock passengers’ stories, he asserts.

“We don’t know if nonverbal signs of deception were there and missed by agents, of if there were no signs at all as the mock passengers knew they were in no danger of arrest, public shame on their families for failing to accomplish the task, or worse,” Frank says.

Bruce Bower has written about the behavioral sciences for Science News since 1984. He writes about psychology, anthropology, archaeology and mental health issues.

More Stories from Science News on Psychology