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NCJ Number: NCJ 186441     Find in a Library
Title: Forensic "Lie Detection": Procedures Without Scientific Basis
Author(s): William G. Iacono Ph.D.
  Journal: Journal of Forensic Psychology Practice  Volume:1  Issue:1  Dated:2001  Pages:75 to 86
Date Published: 2001
Page Count: 12
  Annotation: This paper provides a critical overview of the scientific status of the control question test (CQT), the type of polygraph test most likely to be used in forensic settings.
Abstract: Because there is no characteristic physiological response necessarily linked with lying, it is not possible to ask a person to answer a relevant question about an alleged misdeed, record nervous-system reactions, and make a determination of truthfulness. Polygraphy has attempted to circumvent this problem by including, in addition to a relevant question, a comparison question that is also used to elicit physiological reactions. If a suspect responds more strongly to the relevant question, guilt is indicated, while similar sized responses to both types of questions signify innocence. This relevant/irrelevant test (RIT) format has been found wanting even by proponents of polygraphy, because the irrelevant items do not provide an adequate control for the emotional impact of simply being presented with the accusatory relevant question. The CQT is an effort to circumvent the problems inherent in the RIT by introducing a so-called "control" question, the response to which is compared to the relevant question. Control questions are intended to elicit a lie or at least concern by posing a vague question that covers possible minor misdeeds from a person's past. The theory of the CQT assumes that it is highly likely that every person has hurt someone or lied to an authority figure, so these questions will provide an example of a subject's physiological reactions when lying. For the CQT to be valid, two assumptions must hold. The first requires innocent individuals to be more responsive to control than relevant questions. The second requires guilty persons to respond more intensely to relevant than control questions. These assumptions can be easily challenged, making CQT biased against innocent individuals and vulnerable to defeat by artificially augmenting responses to control questions. These conclusions are supported by published research findings in the best social science journals. 17 references
Main Term(s): Police policies and procedures
Index Term(s): Polygraphs ; Polygraph techniques ; Investigative techniques ; Polygraph reliability
Type: Report (Study/Research)
Country: United States of America
Language: English
Note: For an opposing argument, see NCJ-186442.
  To cite this abstract, use the following link:

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