Lying has never been more difficult, and Dr. Charles Honts is largely to
thank. Honts is internationally recognized as a top expert on credibility
assessment. He has published and/or presented over 300 scientific papers on
and frequently appears in courts around
the world as an
expert witness. He has also given expert testimony in the areas of interrogation and false confession, eyewitness identification, and the forensic
interviewing of children. In this interview, Honts explains the process of a
typical polygraph interview, as well as the effects, history, and future of
Who is your mentor?
I was an
undergraduate biology major until the beginning of my junior year. That’s when
I got hooked on one of Albert Prestrude’s sensation and perception courses I
took as an elective. Prestrude also had a lab in dark adaptation that I worked
in for a few semesters. After my time as an undergraduate, David Raskin became
my academic mentor. Raskin basically formed my career. He remains a good friend
and still contributes to psychology even at 80 years old. We’ve got a book
that’s going to come out next year, so it’s been a long, great relationship.
What has been the most
project you have taken part in, both for yourself and for others?
the most impactful thing I
ever did was my master’s thesis project
Countermeasures, because it was the first study of its kind to look at the way
people could try to be polygraph tested. It’s my citation leader to this day.
How widespread are lie
detection tests used, both in the US and in other countries?
nearly ubiquitous. In the US, every police department for a city of
approximately 25,000 or larger has at least one polygraph examiner on staff.
All federal agencies with law enforcement or national security responsibilities
have them too. The FBI has over 100. There are many examiners in Canada and
Mexico. The growth of polygraph tests is exploding in the Spanish speaking
world across Latin and South America. Tests are widespread in Asia, Japan,
South Korea, China, Indonesia, and Singapore. There’s even beginning to be a
greater application in Europe. For example, the Belgium police have a staff of
polygraph examiners, and there are polygraph examiners spread through many other
European countries too. Although it is certainly not used there at the level
it’s used here, it does seem to be growing.
How do these tests work? What
signals are looked for in subjects?
some variability, but the standard polygraph looks at three things. It looks at
respiration with sensors that go around the body to measure the respiratory
cycle. It measures electrodermal activity, which is the amount of sweat on the
palm of the hands. The polygraph also measures relative blood pressure from an
inflated cuff on the arm; I can’t exactly tell if person’s blood pressure is
120 over 80, but I can track their blood pressure to tell if it’s going up or
down. It’s also becoming more common to use a device that measures peripheral
vessel motor activity—which is the amount of blood flowing near the skin.
That’s usually taken near the palm side of the thumb, although it can be taken
at other places as well.
There’s also some experimentation looking at new measures. In terms
data, the most promising of these involves pupil diameter and eye movement.
Those measures have been around a long time, but they’ve only become practical
in the last 7 or 8 years now that we have noncontact ways of measuring them.
For example, it’s now possible to put a bar at the bottom of a computer monitor
to track eye movements and pupil diameter completely without physical contact.
Through these tools, the standard polygraph produces accuracy rates
around 90% in relation to a clear issue. Unlike what you see on TV, the only
problem is that the tests are actually the product of a structured
psychological interview; the interview is important, maybe even more so than
the measurements. In the interview, one must present the intended stimuli in a
proper context to set up the appropriate conditions. It does not work to just
start asking people questions and see how they respond without the proper
structure of the interview.
Could you describe the
of an interview?
typical polygraph, there is an initial getting acquainted part. There’s then a
free narrative part where I let the person explain whatever position they’re in
or have about the story of why they are being tested. That’s a variable that
could take as little as
5 minutes or as long as an hour and a half depending on
the complexity of the issue, and how much the person has to say. After that, I
explain what the tests entails, where the sensors go on the body, that they
don’t hurt, and what the procedure will be like. Then there’s a review of
questions. Finally, the polygraph test is conducted, which typically consists
of around 10 questions. Usually three or four will be relevant questions,
meaning that they relate to the issue
I am trying to access the person’s
credibility on. These questions should be very clear, concise, and easily
answered with a yes or no. However, comparison questions must also be asked,
such as whether a person has ever told a lie before. These questions are used to
evoke physiological responses from the actually innocent that are then used for
comparison and scoring.
How do these tests
recognize the difference between guilt and nervousness?
the tests do a really good job with general nervousness. For example, if a
person is super nervous and reactive then they tend to respond to everything
with more intensity. However, the test is only inconclusive if they respond to
everything in the same way; I need to see difference in their responses to form
an opinion about their credibility. I either need to see that
questions are stronger than the comparisons, in which case I will conclude the
person was being deceptive about the issue under investigation. Or I need to
see that the comparison questions are stronger than the relevants, in which
case I will conclude the person was truthful.
I also repeat the list of questions at least three times. It’s fairly
common that people calm down after the first round, because they know I’m going
to do what I said I would. I haven’t used any surprise questions. Everything I
told them would happen has happened. Thus, after three repetitions the data is
often much clearer.
What is the potential for
abusing polygraph tests?
potentially disturbing thing happens when agencies use the polygraph as a prop
for an interrogation. There’s a whole area in social psychology called the
bogus pipeline, which is a set of social psychology experiments about tricking
people into thinking there is a lie detector. The results show that tricking
people increases the number of confessions and also the number of false
confessions too. Saul Kassin and his colleagues have shown that very clearly.
I don’t know how often that happens, but it does happen with some frequency,
because I have testified a number of times over the last 5 or 10 years in
In one big case, a young woman was raped and murdered in Nassau County,
New York. The investigation went on for a long period of time and police
eventually ran 26 polygraphs on different potential suspects. Then they said
that a suspect named John Kogut had failed. They interrogated him
hours, until he eventually gave three confessions. None of this was recorded,
so we don’t actually know how these confessions evolved. The first two didn’t
the case facts, but Kogut’s third confession did, in which he implicated
two other men. All three were convicted and sent to jail. Seventeen years
later, the Innocence Project used new DNA technology to exonerate them.
However, because of the confession, the state of New York retried Kogut. I
polygraphed him prior to this second trial, and he passed. After that, the
original test was found and, when properly scored, it showed he was truthful
too. It turns out that about half of the people given polygraphs were told that
they had failed when we know that none of them did it. John Kogut was found to
be not guilty at the conclusion of the second trial.
Are there any steps or
may help to prevent this abuse?
aren’t many, and that’s a big problem in the US. At one time, about half of the
states required licenses, so at least there was a licensing board for people to
complain to. But now the number of states that license is much smaller because
of the move toward deregulation over the last 20 years. Idaho’s
a good example,
because it doesn’t have any required license or laws. If a person wants to be a
polygraph examiner, he or she can come to Idaho, buy a polygraph machine, hang
out a shingle, and start running tests. I think it’s hilarious that we license
hair dressers, but we don’t license polygraph examiners. It’s a mystery to me.
One state that does a good job is New Mexico. That state has a strong licensing
and polygraphs have been admissible at trial since the late 70s. Like any other
kind of evidence, there are occasional battles between experts and sometimes
juries go with the tests and sometimes they don’t. Polygraphs seem to be a very
useful tool in the New Mexico courts. I don’t know why more people aren’t aware
that New Mexico has been conducting this natural experiment for about 30 plus
years and that it’s worked well.
If students are interested
in your area of psychology, what classes would prepare them for this role?
students want to go toward academics in this area, then they should take
traditional training in experimental psychology. If students are interested in
actual tests, then they should probably double major in criminal
justice. Then, they will have to go somewhere to obtain the polygraph training,
which is usually done through law enforcement or through one of the national
security agencies. The big staffs are at the FBI, CIA, and NSA, and actually
the biggest polygraph program in the world is now Customs and Border Patrol.
What can we expect
from you in the future?
interests have broadened in the last decade, because it’s been a very difficult
time to do research. Polygraph research is an area that requires external
support to be successful, and the external support has been very difficult
since the recession. I can do confession work a little more easily, so you’re
going to see some publications from me in the next year on the topic of false
I’m also really interested in the fact that the modal way of doing
interrogations in the US has not changed in 40 years. We’re still using
techniques from the 40s and 50s that have been abandoned in much of the world.
We do things that horrify the Europeans, and we don’t get much for it in terms
of catching the bad guys, though we do end up with a fair number of innocent
people falsely confessing. Thus, I’d like to develop a training course to bring
some of the techniques developed in Europe into the US. People will definitely
be hearing from me about that in the future.