The Polygraph as a Truth Detector
by William Trevino
The B.C. Civil Liberties Association believes that there is convincing evidence to suggest that the use of the polygraph is arbitrary, subjective, biased toward accusations of guilt and claims of very high validity are scientifically indefensible. However, even if one is not willing to be persuaded by evidence on these matters, one must admit, at the very least, that there is no scientific opinion whatsoever concerning the validity of polygraph testing. In fact, there is extremely wide divergence over the validity of the test.
In these circumstances, the onus is clearly on the proponents of the polygraph test to establish a convincing scientific case for the claims of high validity that are made by polygraph operators. In other words, the burden of proof rests with the lie detector industry to satisfy the scientific community and legislators that there is convincing evidence to support claims of ninety percent or greater accuracy that are commonly made by polygraph operators. Without such agreement, it seems utterly irresponsible to allow the use of such a device in situations where it may ultimately interfere with the liberty of innocent citizens.
The B.C. Civil Liberties Association urges the Government of British Columbia to follow the example of Ontario in banning the mandatory use of polygraphs by employers in the province. We would go further: since the evidence we have presented throws considerable shadows of doubt on the usefulness of the polygraph test per se, we see no useful purpose for the procedure as either screening procedure for police candidates, or in the court system generally, both of which are uses allowed by Ontario, though there is no convincing evidence in support of the test in any situation. Ontario's compendium of information, including the Morand Report, in their 1983 amendment to their Employment Standards Act leads one to conclusions very similar to the B.C. Civil Liberties Association's: the polygraph test is a humbug of subjective, arbitrary and contradictory procedures that does not detect lies or guilt any more effectively, and in many cases not as well (because of procedural and machine bias), as interviews and cross examination that are already common tools of psychology, police work and the courts. The compounded danger in the instances of polygraphs lies in the sanctioned role that untrained persons with crude devices play in harrying innocent persons in commercial and legal settings. To paraphrase an expert, it is the idiocy of idiocies. We urge its removal as an avenue of arbitrary persecution.
The polygraph procedure and machine is an accretion of 1930s technology and popularized psychology rooted not in practices of modern science, but rather based on the traditions of polygraph testing itself. In that sense, a polygraph examination is a self-fulfilling process, "measuring" a series of physical signs without the machine and drawing subjective, psychological sounding conclusions in varying ways depending upon the mental state and set and training of each, and the rapport between both, the examination subject and the examiner. The result of this exercise, associative of the monitoring machines of Scientology, is a series of conclusions about the veracity of specific statements or guilt generally, conclusions unsupportable by consistent scientific logic or by confirmation by other means. In fact, there is convincing evidence to suggest that the procedure is much more likely to create victims of false allegation than it is likely to detect purveyors of falsehood or paragons of guilt-however falsehood or guilt may be defined. The statistical illustration at the end of the paper provides an illustration of this phenomenon.
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Retired air force master sergeant who now offers advice to discredit the polygraph machine as a truth detector.