Ha’aretz published the following letter from AntiPolygraph.org co-founder George Maschke:
A lying test
Regarding “Cellcom CEO puts execs under the grill” by Hadar Horesh, February 7:
Yitzhak Peterburg’s decision to force senior Cellcom executives to submit to polygraph tests or be fired is a mistake. Polygraph “testing” is simply unreliable. The dirty little secret behind the polygraph is that the “test” depends on trickery, not science. The polygrapher exhorts the examinee to answer all questions truthfully, but secretly assumes that denials to certain questions – called “control” questions – will be less than truthful.
One commonly used control question is, “Did you ever lie to get out of trouble?” The polygrapher steers the examinee into a denial, warning that anyone who would do so is the kind of person who would be guilty in the incident under investigation. But secretly, it is assumed that everyone, even innocent people, have [sic] lied to get out of trouble.
The polygrapher scores the test by comparing physiological reactions to these probable-lie control questions with reactions to relevant questions (e.g., “Did you talk to any reporter about those business plans?”) If the former reactions are greater, the examinee passes; if the latter are greater, he fails. This simplistic methodology has no grounding in scientific method.
Polygraph tests also include irrelevant questions like “Is today Saturday?” The polygrapher falsely explains that such questions provide a “baseline for truth,” but in reality, they are not scored at all and merely serve as buffers between sets of relevant and control questions.
Investigators value the polygraph because naive and gullible examinees sometimes confess. But many truthful persons fail the “test.” Perversely, the test is biased against the truthful because the more candidly one answers the control questions, and as a consequence feels less distress when answering them, the more likely one is to fail. Conversely, liars can beat the test by augmenting their physiological reactions to the control questions. This can be done by constricting the anal sphincter muscle, biting the side of the tongue, or merely thinking exciting thoughts. Although polygraphers frequently claim they can detect such countermeasures, no polygrapher has ever demonstrated any ability to do so, and peer-reviewed research indicates that they can’t.
George W. Maschke
http://antipolygraph.org