Polygraph Devices Used By Law Enforcement

The polygraph is a device that is used by law enforcement to see if a suspect is lying, assuming a person will be anxious. This device is commonly used by law enforcement has been effective, although it has made errors, as well as suspects have found techniques to beat the test. Compared to the Guilty Knowledge Test (GKT), which is more accurate, as well as being harder to deceive.
The polygraph is usually an accurate measure, as it does monitor biological changes moment-by moment. When a person is lying they; in most cases will be anxious, which can be detected by an increase in heart rate, perspiration and other bodily changes. In most cases the test is accurate and can detect changes in these biological markers, however some people are not anxious when lying and others have found ways to cheat the test. …show more content…
A suspect may not have committed the crime and are nervous about having to do a polygraph test, this reaction could be misread on a polygraph; a false positive. Furthermore, suspects can mislead the polygraph test resulting in a false negative. Polygraph tests rely on the assumption that a person will be anxious while lying, but that may not always be the case; a criminal could feel completely at ease while lying and be let go; a false negative. Another method that could be used to misinform the polygraph test is to show an anxious response even when telling the truth on neutral questions to throw off the test. It has also been found that some suspects may use drugs to alter their arousal