Untitled Document

Lie Detection
The Polygraph
Voice Stress Analysis

The Polygraph is the most traditional method of monitoring an applicant or criminal suspect during questioning to determine the truthfulness of the responses. Voice Stress Analysis has a similar purpose/use, but its accuracy in detecting auditory signs of deception during questioning is still debated, and the polygraph is considered a more accurate mechanism for detecting signs of deception.

The Advantage of Voice Stress Analysis, however, is that a suspect or applicant can be screened without their knowledge. Interviews can also be recorded without the subject's knowledge and analyzed later.

	A polygraph and/or lie detector exam is not required by all law enforcement agencies, and there are no state mandates that all agencies in a particular state administer such an exam to applicants.
	There are, however, some states (Massachussetts and New Jersey) which have statutes prohibiting the use of the polygraph or lie detector for applicant testing.
	The polygraph or VSA is not allowed to be used in Europe to test police applicants.
	The FBI did not require a polygraph exam of all applicants until recently, when they discovered a "MOLE" working in an intelligence capacity within the agency.
	The CIA trains its officers in the Clandestine Service how to mask/control their physiological responses during a polygraph exam.
	Read the not so complimentary news about the Polygraph

This section serves to dispell some of the myths surrounding the polygraph, which is more commonly called a "Lie Detector." The information on this page is the result of having utilized the polygraph as an investigative tool during criminal investigations, and for applicant screening in the police officer hiring process. Additional insights come from personal research on the use of the polygraph, beginning in 1983.

Erroneous beliefs regarding the polygraph:

The machine can detect/determine if a person is lying
Fact: The machine only measures your physiological responses, such as blood pressure, galvanic skin response and heart rate. A machine cannot tell if you are being truthful. That is determined by the polygraphist after examining the chart/graph of your physiological responses.
The OBVIOUS: The polygraphist is the weak link.

You can beat the polygraph
Fact: The polygraph accurately measures your physiological responses unless there is some technical malfunction. With the advent of laptop computers, the process has become much more accurate and reliable.
If you are nervous during the exam, the polygraph will indicate that you are not truthful
Fact: Most people are nervous during a polygraph exam. It would even look suspicious if you were not. The polygraphist develops a base line of responses known to be truthful in your nervous state, and deviations from that baseline are scrutinized further.
Some people can lie without being detected during a polygraph exam
Fact: There are standards of how much a person's physiological responses must deviate from the baseline before deception is suspected. Some persons' responses are too flat to draw a conclusion concering deception or truthfulness. The results would then be considered "inconclusive."
NOTE: The use of some drugs prior to the exam can result in "flat responses," but if the use of such drugs is detected by the agency, your attempt to control your responses is obvious proof of being deceptive. Some polygraphists will ask you if you had taken any drugs prior to the exam. If you are a liar to begin with, that question is stupid, unless you also have to submit to a drug test after the exam.
If you are polygraphed for employment, all the employer is concerned about is whether you are honestly answering all questions, and if you do so, you pass the exam.
Fact: Some people still believe in fairy tales. If you admit to certain criminal acts, you may find yourself unable to go home without first posting bond.
Polygraph Results cannot be used in a criminal trial.
Fact: The rule varies across the United States. Results CAN be introduced at trial in some states, but only after prior stipulation to such introduction by both the prosecution and defense, and before the exam is actually administered (obviously).