Friday, 7 November 2003
Pitiful polygraph promotes paucity of protection
The confession of Gary L. Ridgway, the so-called Green River Killer of Seattle, has lit up the media and the blogosphere alike. I would like to emphasize one oft-overlooked point about this affair that reinforces what the skeptical community has argued for years.
Ridgeway volunteered for — and passed — a polygraph in 1984. Despite the overwhelming evidence (collected in nearly a century of research) that the polygraph and its predecessors are not effective tools for detecting deception, the Department of Energy, Federal Bureau of Investigations (FBI), and Central Intelligence Agency (CIA) still rely heavily on them. The tests do little to protect us because they are so easy to manipulate; yet we continue to expend resources administering them, training staff to administer them, and following up on results. Meanwhile, false "passing" scores give a false sense of security, and false "failing" scores arouse undue suspicion. Ridgeway, for example, admitted to killing people both before and after passing his polygraph.
Could the local authorities have recommitted the resources it wasted on polygraph testing to more effective techniques? Sure. Would that have helped them catch Ridgeway sooner and saved the lives of some of his victims? We will never know.