Introduction to Polygraphy
The polygraph is a device that measures and records a variety of physiological indicators, such as blood pressure, pulse, respiration, and skin conductivity, during questioning. The name is derived from the Greek words “poly” (many) and “graphos” (writing). Essentially, you can derive the meaning of “many writing” which is rather accurate since the machine records the various physiological responses already mentioned.
Polygraphy is the procedure used to attempt to detect deception with the use of the polygraph instrument. This is based on the theory that deceptive answers will give readings that are markedly different from honest ones.
In some countries, this is used to interrogate criminal suspects by investigators and candidates for sensitive jobs by human resource teams.
However, it must be noted that the American Psychological Association has stated that “most psychologists agree that there is little evidence that polygraph tests can accurately detect lies.” Hence, calling it a “lie detector” is rather a misnomer, or wrong naming.
Timeline of the Modern Polygraph
Definition of Relevant Terms
- admission a statement of facts or a partial acknowledgement of guilt usually given with some justification or exemplification in admitting
- confession direct acknowledgement or statement of guilt
- deception the act of deceiving or misleading, usually accompanied by lying
- diastolic blood pressure the downward blood pressure caused by the relaxation of the heart and the closing of the valves
- electrodermal response also referred to as the psycho-galvanic skin reflex or the galvanic skin response, it refers to the changes in the skin’s electronic resistance due to external stimuli
- emotion a strong feeling usually directed at an object or to a person, and is generally accompanied by physiological changes in the body
- environment the sum total of a person’s entire situation
- heredity the genetic transmission of physical and mental traits from one generation to the next
- interview simple questioning of a willing and cooperative subject
- interrogation forceful questioning of a reluctant subject
- lying the act of conveying falsehoods or creating a false impression
- normal response any activity or inhibition of a previous activity of an organism or part of the organism resulting from stimulation
- ordeal one of the oldest forms of detecting deception done by subjecting an individual to an arduous trial that is often lethal
- systolic blood pressure the upward blood pressure shown as the apex of a curve in a graph caused by the contraction of the heart, valves are open and blood is rushing to the arteries
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