Do Polygraph Tests Really Detect Lies?
Do polygraph tests, also known as lie detector tests, really
work? If you want the yes or no answer that is closest to the
truth, it is NO! Of course they sometimes "work," since
much of the time they are used to scare people into confessions
or admissions of guilt. But they are very unreliable as a way
of detecting lies.
After 9/11, the polygraph failure rate went to 50% for agent
applicants at the FBI. Did liars suddenly start applying for
jobs? No, but the testers were instructed to read the tests differently.
Unfortunately this meant throwing out some honest people with
the few dishonest ones. Imagine what this would do to your future.
For all of their lives these mostly innocent people will have
a record of a failed FBI polygraph following them. Think about
that before agreeing to take such a test.
Most scientists now agree that polygraph "testing"
is junk science. In fact, John Larson, one of the pioneers of
polygraphic lie detection, says "I'm sorry I ever had any
part in it's development." The test is valued by governments
and others because it is useful for getting damaging admissions
from people, especially those who don't know that the test is
How about others who might have an obvious interest in such
a test. What do they say?
"[The CIA's] reliance on the polygraph is truly insane."
That was from former CIA Director John M. Deutch.
"...the use of this highly flawed instrument should be
radically curtailed." That was from former CIA Director
R. James Woolsey.
Unfortunately, the test is actually biased against the truthful.
This is because the more honestly one answers the "control"
questions, the more likely one is to fail. Meanwhile, hardened
criminals have proven they can lie throughout the test without
In fact, there isn't even agreement among believers in the
polygraph as to why it works. There are three common theories.
The first is that a subject reacts when questions that strike
sensitive areas, whether he is telling the truth or not. This
theory would indicate that your nervousness (natural under the
circumstances, right) might be taken as dishonesty.
The second theory is the theory of conflict. It supposes that
a measurable physiologic disturbance takes place when a subject
is caught between a habitual inclination to tell the truth and
a strong desire not to admit to certain actions of facts. Some
researchers think that if this concept is valid, it is only when
conflict is intense. Of course habitual liars may be measured
as honest in this case.
The most accepted theory is the threat-of-punishment theory.
It says that a large physiologic response accompanies lying because
a subject fears consequences for failing to deceive the operator.
In other words, a subjects own fear of failing is what causes
the response. The problem that many researchers note is that
one who does not fear the results of his failure should not produce
Experts argue about why the polygraph works, scientists call
it junk science, pioneers in the field regret their involvement
in its development, and CIA officials think it is unreliable.
Does the polygraph test or "lie detector test," work?
It is clear that it does not work with any consistency.
It can be dangerous to your freedom and reputation to take
it - even if you have nothing to hide.
Excerpted from: How
to Beat the Lie Detector Test.