If you travel frequently, then you
have probably endured more than one security screening interview at an
airport. At passport control, for
example, border agents ask a few questions, stare at your passport, check you
on electronic databases, and then send you on your way.
The purpose of these interviews,
of course, is to catch people who are being deceptive. This is a remarkably difficult job. Thousands of people are streaming through
airports every day, and only a very small fraction of them are actually being
deceptive in any significant way.
Can those few liars be caught
effectively?
This question was explored in a
field study by Thomas Ormerod and Coral Dando published in the February, 2015
issue of the Journal of Experimental
Psychology: General.
They trained two samples of
security agents on different methods of screening for deception.
One method focused on finding
suspicious signs that are supposed to distinguish lairs from
truth-tellers. This technique, which is
typical of what is taught to security screeners, involves a scripted set of
questions. As passengers answer these
questions, agents look for signs of deception like nervousness or a passenger
dressed inappropriately for the trip they are going on.
The other method focused on the
security interview itself. This
technique uses a lot of open-ended questions designed to get the passengers to
talk about themselves. The agent asks
questions of general knowledge that someone with that background should know. For example, a passenger who claims to be a
student at the University of Texas should know where the Student Union is or
how to get to the airport from campus.
The technique is designed to give the passenger very little control over
the direction of the interview.
Deceptive individuals like to control the conversation, so that they can
focus on the details that they want to discuss.
After this training, about 200
deceptive passengers were sent through security over an 8-month period. Notice, this means that most passengers that
any agent saw were genuine passengers.
The deceptive passengers were recruited to participate in the
study. They were given payment to be in
the study and a significant amount of additional money if they passed through
security without being called aside for further screening. So, the deceptive passengers had some
incentive to get through security. The
ability to detect whether this group was deceptive was compared to the
screeners’ likelihood of sending genuine passengers for extra screening whose
demographic characteristics matched those of the experimental sample.
A few weeks before participating
in the study, the deceptive passengers were given a cover story to learn that
was tailored to their age and appearance.
The example given in the paper was a male police officer who was told to
imagine that he was working as an engineer near his hometown and was traveling
to Chicago to take part in a fencing competition. The deceptive passengers were told to do research
to add information to their backstory. A
subset of the deceptive passengers were also given several opportunities to be
deceptive at different times, to see if they could improve in their ability to
fool the screeners.
The results were striking. Screeners trained with the interview
technique caught about 70% of the deceptive passengers, while those trained
with the traditional method of looking for cues detected about 5% of the
passengers.
You might thing this reflected
that the screeners trained with the interview technique just sent more people
for additional questioning than those trained in the traditional way. That was not the case. The agents who learned the interview
technique were no more likely to send other passengers for additional screening
than those who were trained in the traditional way.
You might also think that the
interview technique takes longer. It
does not. Agents trained with each
technique spent about 3 minutes with each passenger. The big difference was that those trained
with the interview technique asked more open-ended questions and gave the
passengers more time to speak than those trained in the traditional way.
Finally, those passengers who were
given several opportunities to get through screening were caught at about the
same rate for each try. This finding
suggests that it was not straightforward for passengers to learn to beat the
system.
The reason why the system is hard
to beat is straightforward. If you claim
to be someone very different from who you are, there is a wealth of life
experience that you simply don’t have.
All of the specific details of life from where you shop to how you drive
home to what buildings you pass on your way home are second-nature when you are
telling the truth and are absent when you are involved in a large-scale
deception. These security interviews allow
agents to capitalize on the absence of this knowledge when interviewing
passengers.
Finally, this research is a great
demonstration of the way that psychological research can be used to solve a
practical problem. First, the interview
technique itself is drawn from extensive research on deception. Second, the test itself is quite
well-constructed, and the researchers do a good job of ruling out a number of
alternative explanations for the results.
