Ann Geracimos reports for the Washington Times. Unfortunately, it seems that Mrs. Geracimos interviewed only polygraphers for this article, and in explaining to her how polygraph “tests” are interpreted, they apparently neglected to explain the trickery behind “control” questions. Excerpt:
The word “polygraph” means “many writings” in graph form — a simple definition that gets considerably more complicated when applied to the polygraph machine.
About all that proponents and opponents of this device can agree on is that its operation involves as much art as science because it is the interpretation of graphs that counts.
Few people anywhere claim that the machine better and somewhat incorrectly known as a lie detector — is infallible. At best, it is what Frank Horvath, a professor of criminal justice at Michigan State University and a past president of the American Polygraph Association, calls “a diagnostic tool.” At its worst, it traps people who are “truth tellers” by implicating them falsely.
The machine measures a person’s physiological reactions — changes in heart function, respiration and perspiration — to a carefully phrased series of questions that result in a computer printout similar to that of an electrocardiograph. Generally, a significant change in vital signs — an increased heart rate, etc. — indicates a person is lying.
The exam is administered by a polygraph examiner trained to read the results and upon whose expertise the outcome depends. Depending on the reason for the test, the examiner can determine the worth of the exercise or rule the outcome inconclusive. At least 60 hours of college work — or equivalent experience in police work — are required for trainees.
An examiner reviews with the test taker ahead of time the language employed to be certain no words are used that the subject does not understand. The examiner also establishes what is called a base line to determine the subject’s normal nervous response, given that most people are anxious to some degree in such a setting — at least for the first time.