Accuracy Of The Polygraph - Research Paper Example

The Polygraph: Can it Really Detect Lies? The idea of knowing exactly when a person is telling a lie is indeed a topic of great interest. A lot of efforts have been made to come up with ways to do this. Traditionally, in the past, interviews and interrogations were widely used in trying to reveal deception. On the modern setting, there are the so called “lie catchers” who are professionally trained to use body signals and unusual behaviors, given by their test subjects, as means to know whether or not they are lying. Arguably, none of them have been successful in creating clear-cut parameters on the basis of catching a lie. It is only in the 20th century that a more scientific approach is developed where the psychophysiological responses of a person are the primary indicators in determining a lie (Board on Behavioral, Cognitive and, Sensory Sciences [BBCSS] and Committee on National Statistics [CNSTAT], 2003). This method is widely known as the polygraph test. The central piece to this test is the polygraph instrument, or simply polygraph. Also called the lie detector, the polygraph has the capability to record physiological responses of a human being under examination; such responses will manifest on the blood pressure or heart rate, respiration rate, and skin conductivity. The instrument works under the assumption that such physiological responses would exhibit a different behavior in the act of deception as compared to their behavior before the supposed lie is committed. Applications of the Polygraph Test There are three major applications of the polygraph test: pre-employment screening, employee screening and even-specific investigation. Arguably, the most wide-spread application of it is its use on event-specific investigations such as criminal investigations; counter espionage screening; counter-intelligence; counter-terrorism and combating of corruption (“Background Information,” n.d.). As a tool for employee screening, the instrument is used with current employees of a particular company to know if they have committed a prohibited act. On the other hand, for pre-employment purposes, the polygraph is used in determining specific applicants who may have the tendency to commit prohibited acts (BBCSS and CNSTAT, 2003). The Polygraph Test The whole procedure of the polygraph testing consists of three stages: the pre-test, the in-test and the post-test. The pre-test phase is where the method of the procedure is explained to the person being examined. At this stage, it is important to establish a rapport between the polygrapher and the examinee because the subject needs to be preconditioned that the instrument is capable of detecting deception. Also, included in this stage is the reviewing of the possible questions that might come up during the testing proper; explaining each question to the subject in order to create a mutual understanding for both parties. Overall, this phase of the procedure molds the emotional state and expectations of the subject for the duration of the test (BBCSS and CNSTAT, 2003). Often, an additional stage is included, called the stimulation test or the “stim test,” in a polygraph test where a simulation of how the in-test stage is administered and to show to the subject that the instrument is accurate in detecting lies (“Truth About Lie Detectors,” 2004). After the stim test, the subject is now ready for the official questioning where answers can only be a yes or a no. Firstly, the instrument is hooked on to the body of the subject to collect the necessary physiological responses. A pneumograph is wrapped around the chest of the subject; this will enable measurement for the rate of respiration. Additionally, a blood pressure cuff is placed around the arm to measure cardiovascular activity. For the electrodermal response/skin conductivity, several electrodes are used and are attached to the subject’s fingertips (“Truth About Lie Detectors,” 2004). The questioning starts when everything is all set up. The polygraph will record all the responses the subject has given for each set of question; this record is presented in a form of a chart. The post-test, the last phase of the procedure, is mainly characterized as an interrogation part. The polygrapher may pursue to question further the subject on the part of the questioning where he exhibited strong reactions. Though interrogation approaches differ greatly, the usual practice is to ask the subject on why he reacted strongly on a particular question (Maschke and Scalabrini, 2005). Questioning Techniques There are several questioning formats used in a polygraph test. The most widely used format in the United States is the Control Question Test (CQT). The CQT is an approach where physiological responses to “relevant” questions are compared to that of “control” questions. Relevant questions are those that focus on the purpose of the investigation (e.g., Did steal the money?), while control questions are those asked for purpose of comparison (BBCSS and CNSTAT, 2003). Control questions are generally broad in scope but the nature is similar to the relevant questions (e.g., Have you ever stole money before?). Moreover, control questions are designed to rouse more fear than relevant questions. This is because control questions are geared to elicit reactions towards the subjects past truthfulness (“Truth About Lie Detectors,” 2004). A verdict is reached when a conclusive difference on both reactions is exhibited by the chart. Technically, greater response to relevant questions than to control questions is a sign of deception; hence, the subject passes the test. If it’s the otherwise, then the subject fails. If there is no distinctive difference between the two reactions, the verdict would be “inconclusive” (2004). Other formats of polygraph questioning technique are relevant/irrelevant technique, concealed information technique. Relevant/irrelevant technique is usually administered on employee screening application. The underlying assumption of this format is that a deceptive subject would obviously react differently to the relevant and irrelevant questions. A subject will be decided as innocent only the he has the same reaction for both the test questions. On the other hand, the concealed information technique is used to determine a guilty person using the information based on a particular crime as questions. This format is further broken down into types, namely peak-of-tension test (POT) and guilty knowledge test (GKT). POT is normally composed of 5-9 questions that closely resemble each other, while GKT involves multiple choice type questions with questions only a guilty subject could know. On the Accuracy of the Polygraph From current assessments, a polygraph examination administered by a highly proficient examiner can have an accuracy of about 90 %. Apparently, one vital factor that could affect the accuracy of examination is the level of competence of the examiner admonishing the exam; this suggests that a more proficient examiner can result to a more accurate examination result. Moreover, on the literature produced by the National Research Council (2003) where they carried out a thorough review of existing researches about the polygraph, it was concluded that the accuracy of the polygraph can range from 81- 91 percent; this figure was further described as being “well above chance, though well below perfection” (Grubin, 2010). Aside from the findings mentioned above, there have been comparative studies showing that the accuracy of a polygraph test is at par, if not better, with other forms of evidence. In one particular study, for example, the results obtained on the accuracy of the polygraph exam were comparable to the results generated by fingerprint analysts and document examiners (“How Accurate,” n.d.). Controversies on the Validity of the Polygraph Much controversy has been given about the issue on the accuracy of the polygraph; mainly coming from the doubts about its validity. The issue centers on the physiological responses as main indicators of the act of deception. It was argued that an evidence has not been established where a particular physiological response is uniquely associated to the act of deception. Moreover, same physiological responses can be elicited from a subject under a totally different condition. Factors such as the subject being nervous during the process of questioning and him being non-anxious for the entire process can very much influence the outcome of the procedure. It is, therefore, misleading to characterize the polygraph procedure as an entirely physiological measurement technique when it is clearly a product of an interrogation process and psychophysiological testing (National Research Council, 2003). In the book The Lie Behind the Lie Detector (Maschke and Scalabrini, 2005), the authors tried to expose the so called “lies” of the polygraph machine and why it does not hold validity when it comes to detecting lies. One particular focus of the book is on the CQT questioning format. It was said there that CQT’s validity has never been scientifically established. Additionally, contrary to its name, “Control Question Test” is lacking in scientific control. Further, it stands on the claim that it cannot be considered a standardized psychometric test; citing Professor John Furedy of the University of Toronto who suggested that “…the CQT is not a standardized ‘test,’ but an ‘unstandardizable interrogatory interview. One consequence is that the examiner’s subjective opinion may influence the outcome…” To put it simply, the CQT have no scientific validity which, therefore, renders the polygraph test not valid at all. Maschke and Scalabrini (2005) also quoted Dr. Drew Richardson, a retired Supervisory Special Agent at the FBI, who said that on one of the United States Senate Committee that “the polygraph screening is completely any theoretical foundation and has absolutely no validity…the diagnostic value of this type of testing is no more than that of astrology or tea-leaf reading.” Dr. Richardson further suggested that his own experience together published scientific research has proven that anyone can be taught the polygraph exam. Indeed, numerous countermeasures have been developed for the purpose of beating the polygraph exam; one of those is by just refusing to undergo a polygraph screening. Polygraph Countermeasures As defined by Dr. Gordon Barland, countermeasures are “deliberate techniques that deceptive subjects use in an attempt to appear non-deceptive when physiological responses are being monitored during a psychophysiological detection deception examination” (Maschke and Scalabrini, 2005). While countermeasures can be used by deceptive subjects to pass a polygraph examination, it can also be used by truthful persons to protect themselves from “false positive” results or the misclassification of innocent subjects. There are three basic ways for protecting oneself from false positive outcomes, these are: refusal to submit to a polygraph interrogation, complete honesty, and the use of polygraph countermeasures. Refusal to submit to a polygraph interrogation is the surest way to protect oneself from false positive results. A subject has little to gain and much to lose in agreeing to undergo a polygraph interrogation (2005). Passing the test will not give one much credit, investigators may well continue to suspect one no matter what. On the other hand, failing will only confirm their supposed suspicion and it can very well be leaked out to the public. Another way is to be completely honest. Once under the examination, a subject can very well tell the examiner that the polygraph is but a lie; that the stage called “stim test” is just used to precondition each subject to believing that the test is infallible. Finally, the last approach into avoiding false positive outcomes is the use of countermeasures. Polygraph countermeasures are classified into two, namely behavioral and chart-recording manipulation. Behavioral countermeasures are those methods that a subject can do to appear truthful/honest to the examiner; this may include may include making a good impression to the examiner, being polite and cordial, and being on time during the interrogation. On the other hand, chart-recording manipulations are those that can actually affect or alter the physiological responses that will be measured by the instrument. There are a lot of ways to do a chart-recording manipulation countermeasure. Basically, any activity that can affect the breathing and cardiovascular responses of the body is acceptable. These may include, but not limited to, breathing pattern alteration, performing mathematical calculations, biting the side of the tongue, or by just dong simple physical movements. The accuracy of the polygraph test has been a long standing controversial issue. A great deal has been firm on the belief that the physiological responses are not definitive indicators of the act of deception. There is no unique set of physiological responses clearly associated with lying. To add to that, format of questioning – with great focus on CQT – is suggested to be misleading. Majority of psychologists and scientists are in agreement that there is little basis for the validity of the lie detector test. Despite this, the use of the polygraph is till widespread; the most common setting is on employment screening, case-specific investigation, and the monitoring of criminal offenders under probation. References American Psychological Association. (2004). The truth about lie detectors (aka polygraph test). Retrieved November 17, 2012, from http://www.apa.org/research/action/polygraph.aspx. Grubin, Don. (2010). The polygraph and forensic psychiatry. J Am Acad Psychiatry Law, 438-446. Grubin, Don and Marsden, Lars. (2006). Accuracy and utility of post-conviction polygraph testing of sex offenders. The British Journal of Psychiatry, 479-483. Maschke, George and Scalabrini, Gino. (2005). The lie behind the lie detector, 4th digital edition. AntiPolygraph.org National Research Council. (2003). The polygraph and lie detection. Polygraph Investigative Service. (n.d.). How accurate is the polygraph test?. Retrieved November 17, 2012, from http://www.polygraphis.com/WebsiteFAQ.htm. Read More