Polygraph 'reliability' lower than stated


This letter is in response to your article about the Kappa Sigma member taking a polygraph test ("Polygraph test shows calls to MEChA member accidental," March 8). In the article, you quote Floyd Lawrence of Southwest Polygraph as stating that polygraph examinations (commonly known as lie detector tests) are 95 to 98 percent RELIABLE. Mr. Lawrence is in the business of making money off of administering polygraph examinations. While I don't doubt his commitment to his art, I question the usefulness of his findings.

As a social scientist, I take issue with the perception given by Mr. Lawrence that Polygraph Examinations are VALID (i.e. accurate at telling if someone is lying or not). "Reliability" only refers to a test instrument's ability to give the same readings when things are the same, i.e. test-retest reliability would be asking someone the truthfulness of a statement today and tomorrow. Just because the polygraph examiner interprets the readings on the machine as being true both times does not make it true, only consistent.

Polygraph examinations are banned by law from the workplace because they are highly inaccurate. Several multiple choice questionnaires about honesty are more valid. Unfortunately, several government agencies are exempt from these laws regulating polygraph examinations (such as the Department of Defense), because there is no easy way to tell if someone is telling the truth, so these agencies just use polygraph examinations and hope for the best.

According to Dr. David Lykken (in a 1979 paper titled "The Detection of Deception" in Psychological Bulletin, pages 47-53), polygraph examinations are accurate only 64 to 71 percent of the time; he cites many studies to back up this statement. Thus, in the example stated in the article, the polygraph examination of Mr. Herskovitz is only slightly more accurate than tossing a coin and calling it "heads he's telling the truth, tails he's lying."

I would suggest that instead of using pseudoscience to defend himself, and wasting money on meaningless honesty tests, Mr. Herskovitz and Kappa Sigma look at ways to apologize to Mr. Martinez and MEChA, and seek ways to prevent events like this from occurring on the UA campus in the future. The issue now is not one of what actually happened (honesty), but what the campus community now perceives about the parties involved (avoidance of responsibility and maturity).

Matthew Troth
management & policy Ph.D. candidate