Since there's all this talk going around about lie detectors,

[Jackpine Radical]

here's what the American Psychological Association has to say on the topic:

http://www.psychologymatters.org/polygraphs.html

Most psychologists and other scientists agree that there is little basis for the validity of polygraph tests. Courts, including the United States Supreme Court (cf. U.S. v. Scheffer, 1998 in which Dr.'s Saxe's research on polygraph fallibility was cited), have repeatedly rejected the use of polygraph evidence because of its inherent unreliability. Nevertheless, polygraph testing continues to be used in non-judicial settings, often to screen personnel, but sometimes to try to assess the veracity of suspects and witnesses, and to monitor criminal offenders on probation. Polygraph tests are also sometimes used by individuals seeking to convince others of their innocence and, in a narrow range of circumstances, by private agencies and corporations.

The development of currently used "lie detection" technologies has been based on ideas about physiological functioning but has, for the most part, been independent of systematic psychological research. Early theorists believed that deception required effort and, thus, could be assessed by monitoring physiological changes. But such propositions have not been proven and basic research remains limited on the nature of deceptiveness. Efforts to develop actual tests have always outpaced theory-based basic research. Without a better theoretical understanding of the mechanisms by which deception functions, however, development of a lie detection technology seems highly problematic.

For now, although the idea of a lie detector may be comforting, the most practical advice is to remain skeptical about any conclusion wrung from a polygraph.

[Fridays Child]

1. A timely reminder that polygraphs aren't necessarily reliable.

Very good. :thumbsup:

[OPERATIONMINDCRIME]

2. The Results Are Probably Reliable 95% Of The Time Though.

One should never put all their eggs in a basket based on the results, as there is never a way to ascertain the truth for certain when using one, but in non-judicial settings they most definitely can in most circumstances lend credence to someone's story or give reason to reject it. It may not be perfect science, but it definitely can still be an incredibly useful tool. One just has to make sure they don't view results as the gospel, since they aren't 100% accurate.

[Jackpine Radical]

3. Baloney.

Or, more properly, Bologna.

Since you obviously didn't read--or else failed to comprehend--the first link, try this one:

http://antipolygraph.org/articles/article-018.shtml

Unfortunately, it is not possible to use the existing polygraphy literature to accurately estimate the validity of the CQT. This state of affairs persists for a variety of reasons (Iacono & Lykken, 1997a), the most important of which is that it is very difficult to conduct research on polygraph test validity that provides an accurate estimate of how well the CQT works in real life.

Laboratory Studies. Two types of validity study are possible. One relies on laboratory investigations where volunteer subjects, often undergraduate students seeking course credit, are asked to simulate a crime. These mock crime studies are too unlike real life to offer any realistic insight to how polygraph tests work in the field. For instance, the consequences of failing a test are trivial; the privacy-invading control questions are apt to be more disturbing to innocent subjects than relevant questions that carry little psychological significance; and {80} guilty individuals are tested immediately after the simulated crime, minimizing the likelihood of habituation to the issues raised in relevant questions. In addition, because the stakes are so low, it matters little if a guilty person fails a laboratory-based CQT, so there is no natural incentive to develop or learn about countermeasure strategies.

Field Studies. Field studies of real-life cases provide the best opportunity for estimating CQT error rates. However, studies based on such cases are severely limited by methodological problems that are generally ignored by CQT proponents. The main advantage of laboratory studies, that one can be certain of ground truth (who is guilty and who is innocent), is the major disadvantage of field studies. Typically ground truth is established by using confessions to identify the guilty and exculpate co-suspects in the same case. Once ground truth is established, the polygraph charts of these individuals can be blindly scored and hit rates for verified guilty and innocent individuals can be determined. About a dozen field studies have been carried out using confessions to determine ground truth (for critiques of these studies, see Iacono & Lykken, 1997a; Iacono & Lykken, 1999; Iacono & Patrick, 1987). These studies vary widely in their methodological sophistication and in reported hit rates, which range from about 50% accuracy for innocent people to nearly 100% for guilty suspects. However, as explained below, these confession-based investigations have one serious flaw in common: the ground truth criterion is not independent of the outcome of the polygraph test.

A major goal of polygraph testing is to solve crimes by extracting occasional confessions from those who fail the tests. Indeed, it is this benefit of polygraph tests that justifies their use in the absence of compelling validity data. Law enforcement agencies tend to administer polygraph tests only in certain cases (Iacono, 1991; Patrick & Iacono, 1991). For most of these cases, investigative efforts have failed to yield compelling incriminating evidence, and it is likely the case will go unsolved unless a suspect confesses. It is at this point in an investigation that suspects are likely to be asked to take a polygraph test. In a case with multiple suspects, only one of whom could be guilty, suspects are tested until one fails. This individual is then presented with the results of the test, and subsequently interrogated in an effort to extract a confession. Even if no confession is obtained, the case will be considered resolved, with the individual who failed the test identified as the suspect most likely to be guilty. If there are other {81} suspects in the same case who have not yet been polygraphed, it is unlikely that they will be tested because: (a) polygraph examiners believe the CQT to be highly accurate, so they are comfortable with the conclusion that the individual with the "deception indicated " polygraph verdict is in fact guilty; and (b) polygraph testing involves an expenditure of a limited resource that could best be applied to other cases which, unlike the one in question, are still in need of resolution.