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GQT Polygraph Test: Scoring and Validity

NCJ Number
Polygraph Volume: 24 Issue: 3 Dated: (1995) Pages: 234-236
M J Crowe; M Chimarys; J Schwartz
Date Published
3 pages
The use of polygraph examinations for detecting deception assumes that physiological responding will be greater when a deceptive response is made.
For purposes of evaluation, the physiological reaction to an issue-related (relevant) question is often compared to that of a probable lie (control) question, a question not directly related to the issue. An examination format which has developed in the field of polygraphy is the General Question Techynique (GQT). This technique brackets and compares the relevant question with a modified or disguised control question about lying during the examination. To evaluate the GQT, 30 different GQT polygraph series were evaluated by nine polygraphers. Results indicated the GQT was valid for detecting deception when charts were numerically scored against the strongest control question. Visually scoring the overall chart was somewhat less accurate but had fewer inconclusive results. Scoring against the weaker control's reaction was not acceptable because such scoring increased the identification of deceptive individuals from the charts at the cost of eliminating any correct identification of charts from nondeceptive people.