December 10, 2003
A. In 1921 the first workable polygraph was invented by John Larson
II. Polygraph Use
A. Polygraph tests are used in more than 56 countries such as Japan,
Canada, Romania, China, Mexico, and Singapore. They have been in use for
over 24 years in Singapore. Singapore uses them in governmental law
enforcement and in multinational companies.
B. Polygraph tests have been used in the United States for almost 100
years. They serve much purpose in the CIA, FBI, and the United States
Department of Defense. All three use polygraphs for investigations as well
as personnel screening. The CIA and FBI use polygraphs to check backgrounds
of potential employees and to see if workers are to gain or keep access to
secret information. Some other uses for polygraph tests are for periodical
employee screening and to be a useful tool for getting confessions.
Polygraphs should not be used to test for lies but rather to deter crimes
and help cause confessions ergo polygraphs do not have to work people just
need to believe that they do.
III. How Polygraphs Work
A. The test measures three unconscious physiological responses by
going through three separate phases.
B. The first phase is a pre-test interview where the examiner finds
out about the case and the person being tested. The examiner watches body
movement like fidgeting and coughing. Body movements like these could be
signs of a guilty person. The second phase is the collection of polygraph
charts. This entails the hookup of three sensors to the subject. The three
sensors are phneumographs (which measure respiration), galvanic skin
response (GSR which measures perspiration), and finally a cardiograph
(which measures blood volume, pulse, and pressure). The next part of the
second phase is the asking of the questions. The three types of questions
are relevant (which relate to the matter under investigation), control
(which are not directly related to the matter but are similar), and
irrelevant (which determine the person's normal physiological response).
Each question is asked at least twice. The third and final phase of the
test is the post test interview. During this final phase the subject is
asked about the responses he or she gave to any of the questions. The last
part is that the charts are scored to tell any significant responses. The
total time for all of this is roughly two to three hours.
IV. Information on Polygraph
A. The polygraph test is dependent on the demeanor of the person, how
good the examiner is, and what is being asked. It is also dependent on the
assumption that there are no physiological changes if a person is telling
the truth. The test does not detect lies but rather just record
physiological changes that occur when a question is being asked.
B. Despite ninety percent accuracy polygraph tests have never been
C. FBI is funding research into other types of screening tools such as
thermal imaging, voice stress analysis, and pupil dilation. The first
polygraph measured blood pressure and respiration. The next advance in
polygraph technologies added galvanic skin resistance. A modern polygraph
which tests all three responses costs around 8,000 dollars, but for just
nine dollars and ninety-five cents a simple polygraph that measures
galvanic skin resistance is available at Radio Shack.
D." Most polygraphists are prohibited from asking questions about
religious and political beliefs and sexual matters how ever CIA applicants
are often asked questions of this nature."
A. No one can be forced to take a polygraph test as it is stated in the
Fifth Amendment. The Fifth Amendment states that "No one shall be compelled
in any criminal case to be a witness against himself."
B. The first attempt to introduce polygraph evidence in court was in
1923 in the case of Frye versus United States. The judge denied the
evidence into court.
C. Police often use polygraph tests when evidence is circumstantial.
Usually after police have completed investigation and after forensic lab
has processed all physical evidence. Most useful to help police determine
whether or not they should keep suspecting someone and in obtaining
D. Employee Polygraph Protection Act (EPPA) is a law that protects
employees from being required to take a polygraph test. States that
polygraph can only be used in specific circumstances such as theft,
embezzlement, espionage, or sabotage. Also that polygraphs can not be used
in pre-employment screening except in federal, state, and local government
as well as National Security and Defense. The EPPA allows protection for
employees so that they can not be fired because of the results of a
polygraph test but the way to get around this is just to demote the person.
A. Courts usually deny use of polygraph because of the many questions
about its accuracy. In the United States most states allow polygraph
evidence if both parties agree to the admissibility before the test is
administered. In the United States New Mexico is the only state that allows
polygraph evidence to be admitted just like any other evidence. Thirty
states ban polygraph evidence. In Japan polygraph use is admissible in
VII. Reliable or Not
A. Some reasons why polygraph tests are reliable. The subject is pre-
examined to measure how they react when they lie and also to determine if
the suspect is taking anti-depressant medication that could skew the
results. Second is that very few people can control all three physiological
functions at the same time and in order to do this he or she must be a
pathological liar. Thirdly is that the tests have an eighty to ninety
percent accuracy rate.
B. Many reasons for being unreliable. The first is the errors that lay
within inexperienced examiners. The main type of polygraph test in the
United States is the CQT (control question test), but a huge fault in this
test is that a subjective opinion of the examiner may influence the outcome
of the results. Another fault is that a polygraph examiner needs no prior
education and that any one can take a training course that lasts from six
to eight weeks to become a polygraph examiner. " The most "prestigious"
polygraph school, The Department of Defense Polygraph Institute, churns out
polygraphists after a mere 520 - hour (fourteen week) course of
instruction." Operating a polygraph is as simple as reading the manual. The
United States has the most polygraph examiners with between three and four
thousand polygraphists in the government and private polygraph companies.
The biggest variables are effectiveness of the examiner, mental as well as
physical state of the subject, and the place where the test is taken. False
Positives occur when the response of a truthful person is determined to be
deceptive. This can happen because of many reasons. When innocent people
get nervous or overanxious or uncomfortable because of the equipment of
questions can produce a false positive. False negatives are when the
response of a deceptive person is said to be truthful. Some guilty people
have trained themselves to "beat" a polygraph. They have learned to lie
without causing physiological changes which create false negatives. For
example Gary Leon Ridgeway killed forty-nine women but when they first
suspected him he passed a polygraph test that could have stopped him if it
was truly effective. There are also many ways not to per say "beat" the
test but to skew the results enough to make it invalid. Some examples are
to take sedatives, put antiperspirant on fingertips, tacks in shoe, and
biting tongue, lip, or cheek. The idea of all of theses is to cause a
reaction that can skew the results.
VIII. Ways to protect your self from polygraph tests.
A. The first and utmost way to protect ones self is refusal to take the
B. There are many ways to protect ones self against false positives. The
first is to arrive on time to the test to make sure that any tardiness is
not seen as deception in the eyes of the examiner. Second is to dress nice
and look appropriate so to insure that the examiner does not develop a
bias. Third is to have the whole test video recorded, forth have a lawyer
present, and finally never allow it in court.
A. FBI employees who fail a polygraph have many consequences. The first
is difficulty getting a job where security clearances are needed. Second is
black listing in other federal enforcement agencies and finally
disqualification from FBI employment for life. An interesting statistic:
Since 9/11 fifty percent of FBI applicants failed their polygraph test.
A. Polygraph tests should not be used at all because it is too easy to
buy one, there are to many errors, to much of the test relies on the
examiner, and to many simple ways to skew the test.