The purpose of this project is an analysis of the pros and cons of polygraph use in verification of the accuracy of a subject’s testimony or other statement. Polygraph testing does not have the ability to verify whether an individual is lying with 100 percent accuracy. Thus, it is questionable as to whether a polygraph is a useful tool. There are also instances where polygraphs may produce a false negative, in cases where an individual may be providing false information, but the polygraph does not reveal this information. The polygraph should measure changes in physiological responses in the candidate tested, including changing in pulse and breathing rates. However, there may be instances where an individual is able to manage these rates and deceive the test. How can one determine whether the value of taking a polygraph outweighs the risk of false negatives or lack of 100 percent accuracy? This question is pursued further in the paragraphs below.

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Advantages of Polygraph Testing
According to Grubin (2010), humans generally are incapable of detecting lies without assistance, with a prediction rate rarely above 60 percent. Even “professional lie catchers” are not able to determine rates much better, when attempting to detect deceit in experimental conditions. Thus, polygraphs may serve the purpose of increasing the rate of positive detection of deceit in circumstances where it is most important, including in criminal investigation (Grubin, 2010). Research by the National Research Council suggests that polygraph accuracy ranges from 81 to 91 percent, suggesting the information provided by polygraph tests are far above chance, although not perfect in their result (Grubin, 2010). Thus, in cases where security has been compromised, the use of polygraph may help improve detection of deception by a 10 percent increase or more (Grubin, 2010).

Disadvantages of Polygraph
The Law Offices of Hilf & Hilf, PLC. (2014) suggest that the polygraph examination, or lie detector test, are sometimes not admissible in courts, depending on the state the test is administered in. This may be the result of false negatives or other inaccuracies that polygraphs are subject to. McGrath, Cumming, Hoke & Bonn-Miller (2007) suggest that polygraph exams may provide inconclusive data in certain circumstances. The researchers conducted a study of sex-offenders, who participated in periodic polygraph compliance exams, with those not receiving exams. The results of the study suggest that while the individuals in the polygraph group had a lower incidence of new charges of non-sexual violent offences, there were no changes among groups of new sexual or any sexual or violent or criminal offenses compared to the group not receiving polygraph examinations (McGrath, Cumming, Hoke & Bonn-Miller, 2007). Thus, researchers are not clear as to whether the results of polygraph examination provide utilitarian information.

The Committee on Government Operations by the U.S. House of Representatives assisted in evaluating changes to policies regarding polygraph examination after studies suggesting that polygraph testing is a very complex process that can be influenced by many factors. These include examiner training, the environmental setting of a polygraph text, and the types of questions asked. Any variances in these factors can result in higher than average false negatives, which may require an examiner to re-take the test, or which may unwittingly implicate an individual undergoing testing under polygraph regulation (FAS, 2013).

The result of the analysis provided suggests that in very structured and regulated settings polygraph testing, when used with other analytical measurements, may provide information that assists in decision making. However, polygraph testing is a complex process that is prone to error. As a result, polygraph testing is not an ideal instrument to use as a sole vehicle for analysis of deception in any case or criminal/law enforcement setting.

  • FAS. (2013). Chapter 7: Conclusions Polygraph. Retrieved from:
  • Grubin, D. (2010). The Polygraph and Forensic Psychiatry. JAAPL, 38(4): 446-451. Retrieved from:
  • Hilf & Hilf. (2014). The Polygraph Test. Retrieved from:
  • McGrath, R.J., Cumming, G.F., Hoke, S.E. & Bonn-Miller, M.O. (2007). Outcomes in a Community Sex Offender Treatment Program: A Comparison between Polygraphed and Matched Non-polygraphed Offenders. Sex Abuse. 19(4): 381-393.