Saturday, April 25, 2009

Lie Detectors

Ken Alder, The Lie Detectors: The History of an American Obsession (New York: Free Press, 2007), p. 128.

[P]olice examiners regularly wring confessions by putting suspects on sham devices with contemporary flash. In the 1930s a high school principal in Newark, New Jersey, got students to confess to a mock lie box; and a policeman in New York City used a towel and a ticking alarm clock to get a youth to admit filching $10 from his parents. [...] In the 1980s cops were extracting confessions by putting a suspect's hand on a photocopy machine filled with paper printed with the word "LIE!"[*] In our era of cognitive science, cops have taken to placing the suspect's head in a colander with wires attached. Naivete of this sort among criminals may elicit a chuckle -- it got a big laugh in the U.S. Supreme Court -- but the joke is double-edged. Though some suspects may be duped into confessing to a mechanical placebo, cops and prosecutors are also locked in a self-fulfilling prophesy: deciding the fate of suspects on the basis of a doubtful test.

* David Simon, Homicide: A Year on the Killing Streets (Boston: Houghton Mifflin, 1991), 204. For recent practice and the laugh, see U.S. v. Scheffer, 523 U.S. 303 (1998), oral argument 11/3/97, at

United States v. Scheffer (No. 96-1133) -- Oral Argument

Argument of Michael R. Dreeben


Mr. Dreeben: -- In investigations, the polygraph is an extraordinarily productive interrogation tool.

An enormous amount of confessions are given when a suspect either fails a polygraph or believes that a polygraph is about to smoke him out.

I have to say that in that sense there are examiners who believe that it is entirely reliable in this respect, and that it's a great interrogation tool because it's accurate.

There are other people who will say that, well, it's a great placebo.

There is a story of a police interrogation in a State system where the police put a colander on a suspect's head and wired it up to a Xerox machine, and then pressed a button that produced a picture, a little copy that said, you're lying, every time the suspect answered.


The suspect confessed.


So if a suspect believes that the polygraph is accurate and is about to catch him, then it will be very useful to do that.