For instance, the effects of drugs that specifically affect the physiological measures that compose polygraph tests have received little attention. This would leave the outcome of a test to be determined primarily by respiratory activity. Respiration is the least reliable of the three channels that compose a polygraph test, and is under voluntary control, thus making it easy to manipulate. Hence, the use of these drugs could confer an advantage to a guilty person taking a polygraph. There is research investigating a subtype of antisocial personality disorder called psychopathy.
Psychopaths are skilled liars who experience no remorse for their antisocial behavior.
Two studies have found that psychopaths do not have an easier time passing polygraphs when the outcome of the test is based on the physiological data. However, the government s own data indicate that many individuals who fail the physiological test nonetheless are passed by their examiners because they convince them they have done nothing seriously wrong. Impression management through lying is exactly what psychopaths are good at. Hence, there is good reason to believe they could pass screening tests. There are no investigations examining how ethnicity of the examinee affects his or her physiological responses.