THE TRUTH ABOUT LIES : DO LIE DETERCTORS WORK?
Aldrich
No surprise, at least among researchers who study the validity of lie deterctor test results. Repeatedly, lie detectors have proved to ve unreliable indicators of lying
A lie detector, or polygraph, is an electronic device designed to expose people who are telling lies.the basic assumption behind the apparatus is straightforward : The autonomic nervous system of people who are not being truthful becomes aroused as their emotionally increases. Polygraph are designed to deteect the physiological changes that are indicative of this araousal.
Actually, a number of separate physiological functions are measured simultaneously by a lie detector, including changes in breathing pattern, hear rate, blood pressure, and sweating. In theory, polygraph operators ask a series of questions, some of which they know will elicit verifiable, truthful responses. For instance, they might ask a person to provide his or her name and address. Then, when more critical questions are answered, operators can observer the nature of the physiological changes. That occur answer whose accompanying physiological responses devate significantly from those accompanying truthful responses are assumed to be false (Reicherter, 1997).
That’s the theory, at least. The reality is something different : there is no foolproof teecnique for assessing the extent of the physiological changes that can indicate a lie. Even truthful responses can elicit physiological arousal, if the question is emotion laden (waid et Orne, 0982)
How many innocent people accused of a murder, for instance, would not respond emotinally when asked whether they commited the crime, since they know that their future may hang in he balance.
One further drawback of lie detector tests is that people are capable of fooling the polygraph. For instance, biofeedback techniques (see chapter 2) can be employed to prouduce emotional respons to accompany wven truthful statements, meaning that the polygraph operator will be unable to differentiate between honest and dishonest responses. Even biting one’s tongue of hiding a tack in a shoe and pressing on it as each wuestion in answered could be sulficient to produce physiological arousal during each respone, making truthful and deceptive responses indistinguishable (Honts, Raskin et Kireher 1987; Honts et Kireher, 1994 Sleek 1998).
Because of these sources of error, lie detector operators often make mistakes when trying to judge another person’s honesty, the American psycological Association has adopted a resolution stating that, the evidence for the effectiveness of polygraph is still unsatisfactory. Even the major proponent of the use of polygraphs the American polygraph Association admits an error rate between 4 and 13 percent, and critics suggest that research has shown that the actual rate is closer to 30 oercent. Using such evidence. U.S federal law bars employers from using polygraphs as screening devices for mos jobs (Lacono, 1991 Saxe 1994 Lacono et Lykken, 1997).
In short there are good reason to doubt that polygrap test can determine accurately whether someone is lying. For now, then you can be assured that any screts youmight harbor wil remain hidden : No one has yet identified a foolproof way to distinguish people who are telling the truth from those who are lying (Saxe, 1994, Alliger, Liliefeld, et Mithcell 1996).
Techniques for fooling lie detectors focus on artifically elevating emotional responses so that. Truthful and untruthful responses display similar pattens of emotionally. Do you think atack of emotinal response would therefore indicate truthfulness? Or is it possible to fefeat a lie detector by depressing (rather than elevating one’s emotinal response?
source: essentials of understanding psychology by robert s. feldman
