System for and method of detecting polygraph countermeasures

Details System for and method of detecting polygraph countermeasures System for and method of detecting polygraph countermeasures

2002-01-09

2004-06-29

Jones, Mary Beth (Department: 3736)

Surgery

Diagnostic testing

Measuring electrical impedance or conductance of body portion

Reexamination Certificate

active

06757559

ABSTRACT:

FIELD AND BACKGROUND OF THE INVENTION
The present invention relates to polygraph examinations and, in particular, it concerns a system of and a method for detecting polygraph countermeasures.
A polygraph examination utilizes a polygraph instrument that collects physiological data from at least three systems in the human body. Tubes and leads are placed over the examinee's chest and abdominal area to monitor respiratory activity. Two small metal plates, attached to the fingers, are used to monitor sweat gland activity. A blood pressure cuff, or similar device, monitors cardiovascular activity.
A typical polygraph examination is composed of three periods referred to as a pre-test, a chart collection phase and a test data analysis phase. In the pre-test, the polygraph examiner completes required paperwork and talks with the examinee about the test. During this period, the examiner discusses the questions to be asked and familiarizes the examinee with the testing procedure. During the chart collection phase, the examiner administers and collects a number of polygraph charts. The examiner subsequently analyzes the charts and renders his opinion as to the truthfulness of the person taking the test. The examiner, when appropriate, offers the examinee an opportunity to explain physiological responses in relation to one or more questions asked during the test.
However, some deceptive subjects use deliberate techniques in attempt to appear non-deceptive while the polygraph is monitoring their psycho-physiological responses.
There are two particularly problematic types of countermeasures:
Physical countermeasures involve the use of physical means to prompt a response, e.g., biting the tongue, constricting anal muscles, pressing toes against the floor (or against a sharp object within a shoe), etc.
Mental countermeasures involve the use of thoughts that are stimulating, disturbing, engaging, e.g., an arousing thought or a difficult mathematical calculation.
There are elaborate polygraph countermeasures that are taught by major intelligence agencies and also on Internet web sites (one of which is antipolygraph.org) aimed to manipulate the polygraph chart record.
Most polygraph tests are of the CQT variety, in which deception is determined by comparing physiological responses to relevant questions to a baseline determined by control questions. Using countermeasures as described above, it is possible to achieve a response level to the control questions that is greater than the response level to the relevant questions, in which case a “Non-Deception Indicated” result is obtained. In some cases, the response level to the relevant questions is similar to the response level to the control questions, in which case the test results are inconclusive.
Thus, although countermeasure means for beating the polygraph examination are effective and readily available, there exists no effective, systematic method of exposing the use of countermeasures, particularly when such countermeasures are used in a professional manner. There is therefore a recognized need for, and it would be highly advantageous to have, a method of and a system for exposing the use of polygraph test countermeasures. It would be of further advantage for such a method and system to be implementable in existing polygraph systems.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, there is provided a system for detecting the use of countermeasures by a subject of a polygraph test, the system including: (a) a polygraph instrument for recording at least one physiological activity of the subject; (b) a sound recording device for recording audio data during the polygraph test; and (c) means for measuring time, operatively connected to the sound recording device.
According to another aspect of the present invention, there is provided a method for identifying a use of countermeasures by a subject of a polygraph test, the method including the steps of: (a) posing a plurality of questions to the subject; (b) determining, for each question, a time interval between an end of the question and a start of an answer by the subject to the question, thereby generating a plurality of time intervals, and (c) comparing the time intervals to identify the countermeasures.
According to further features in the described preferred embodiments, the questions include control questions and relevant questions.
According to further features in the described preferred embodiments, the method further includes the step of: (d) monitoring at least one physiological response of the subject.
According to still further features in the described preferred embodiments, the method further includes the step of: (d) displaying sound waves of the answer.
According to further features in the described preferred embodiments, the posing of the questions transpires during the polygraph test.
According to further features in the described preferred embodiments, the answer is a sound response.
According to still further features in the described preferred embodiments, the method further includes the step of: (d) recording a sound recording of the question and the answer.
According to still further features in the described preferred embodiments, in the comparing of the time intervals, X
C
represents an average of the time intervals pertaining to the control questions, and X
R
represents an average of the time intervals pertaining to the relevant questions, the use of countermeasures by the subject being indicated when a difference between X
C
and X
R
exceeds a predetermined value.
According to still further features in the described preferred embodiments, in the comparing of the time intervals, the use of countermeasures by the subject is indicated when X
R
−X
C
>&dgr;
1
or when X
C
−X
R
>&dgr;
2
.
According to still further features in the described preferred embodiments, No Deception Indicated (NDI) is concluded when a difference between X
C
and X
R
is below a pre-determined value.
According to still further features in the described preferred embodiments, the system further includes: (d) processing means operatively connected to the sound recording device polygraph machine and to the means for measuring time, wherein the processing means for producing time information is associated with the audio data.
According to still further features in the described preferred embodiments, the processing means are designed and configured for identifying use of countermeasures by the subject.
According to still further features in the described preferred embodiments, the processing means are designed and configured for identifying use of countermeasures by the subject based on the time information.
According to still further features in the described preferred embodiments, the processing means are designed and configured for identifying use of countermeasures so as to: (i) calculate for each question of a plurality of questions, a time interval between an end of the question and a start of an answer by the subject to the question, thereby generating a plurality of time intervals, and (ii) compare the time intervals to identify the countermeasures.
According to still further features in the described preferred embodiments, the at least one physiological activity is monitored using galvanic skin response (GSR).
According to still further features in the described preferred embodiments, the processing means are designed and configured to utilize the time information so as to: (i) calculate for each question of a plurality of questions, a time interval between a beginning of the question and a time corresponding to a minimum value adjacent to a galvanic skin response peak to the question, thereby generating a plurality of time intervals, and (ii) compare the time intervals to identify the countermeasures.
According to still further features in the described preferred embodiments, the system further includes: (d) means for displaying the audio data in a graphic form.
According to still further features in the described preferred embodiments, the s

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