Polygraph examinations are popular for their drama, but are they really useful? In many cases, the answer is yes – if you follow some fundamental guidelines and choose an examiner that is qualified and professional.

The earliest known reference of detecting deception by using science instead of ritual is found in the early Hindu "Book of Health and Sciences" (Ayur-Veda). Ayur Veda stated that a liar will demonstrate one or more of these following behaviors:

• A refusal to answer questions

• Nonsensical responses

• Evasive answers

• Nervousness

• Blushing

• Trying every possible means to be excused

• Accusing others

• Attacking the accuser

Today, polygraph examiners focus on biometric measures to identify when someone isn’t telling the truth. There are a minimum of three channels on a polygraph (pneumograph, which measures breathing; cardiograph, which measures heartrate; and galvanic skin responses). These three channels together have a proven accuracy rate of 90% in determining whether or not someone is lying.

If you need a polygraph exam keep the following guidelines in mind:

1. Polygraph examination is not a heavily regulated industry. Find an examiner who is a member of the American Polygrapher’s Association, the National Polygraph Association or similar state organizations. Some less experienced and reputable practioners may present themselves as being certified, so make sure you know who is doing the certification.

2. There is no such thing as a polygraph examination by phone. Although the CIA first initiated the tools variously known as Voice Stress Analyzers (VSAs), Computer Voice Stress Analyzers (CVSAs), Psychological Stress Evaluator (PSE) and Psychological Stress Analyzer (PSA), all of these tools are essentially the same – and have been discredited by several published studies.

3. Individuals who claim that they can teach criminals to "beat the test" invariably end up reinforcing the science. Those who take a test expecting to beat it inevitably fail, thereby reinforcing the accuracy of the instrument.

4. Polygraph examinations have been successfully since the 1920s and continue to gain acceptance in the judicial system. If a person is innocent and willing to be tested, they should find a competent examiner and submit to the test. They will want the test to work, cooperate as much as possible and in an overwhelming percentage, find a well-qualified polygraph examiner will substantiate their claims of innocence.