Well said!
Let’s consider an attempt to use physiological measurement of anxiety for a practical purpose, lie detection. I t is, in fact, difficult to tell when someone is lying, even though many people think they can do so. P eople watch for averted gaze, hand twitches, and so forth, but most of these signals are worthless. Could a machine do better than we do?
The polygraph, or “lie-detector test,” records sympathetic nervous system arousal, as measured by blood pressure, heart rate, breathing rate, and electrical conduction of the skin (Figure 12.20). (Slight sweating increases electrical conduction of the skin.) The assumption is that when people lie, they feel nervous and therefore increase their sympathetic nervous system arousal.
(A bit of trivia: William M arston, the inventor of the polygraph, was also the originator of the Wonder Woman cartoons. Wonder Woman used a “lasso of truth” to force people to stop lying.)
The polygraph sometimes accomplishes its goal simply because an accused person hooked up to a polygraph confesses, “Oh, what’s the use. You’re going to figure it out now anyway, so I may as well tell you. . . .” But if people do not confess, how effectively does a polygraph detect lying?
In one study, investigators selected 50 criminal cases where two suspects took a polygraph test and one of the suspects later confessed to the crime (Kleinmuntz & Szucko, 1984). Thus, they had data from 100 suspects, of whom 50 were later shown to be guilty and 50 shown to be innocent. S ix professional polygraph administrators examined the polygraph results and judged which suspects appeared to be lying.
Figure 12.21 shows the results. The polygraph administrators identified 76% of the guilty suspects as liars but also classified 37% of the innocent suspects as liars. The few other well-designed studies that have been done produced equally unimpressive results. A although many police officers still believe in polygraph testing, most researchers regard the accuracy as too uncertain for important decisions (Fiedler, S chmid, & S tahl, 2002). P olygraph results are only rarely admissible as evidence in U .S. or E uropean courts. The U .S. C ongress passed a law in 1988 prohibiting private employers from giving polygraph tests to employees or job applicants, except under special circumstances, and a commission of the U.S. N ational A cademy of S ciences in 2002 concluded that polygraphs should not be used for national security clearances. But the Psych professor acts like polygraphs are somehow a mystery to her??? Who is buying this BS?!?!