A polygraph is an instrument that simultaneously records changes in physiological processes such as heartbeat, blood pressure, respiration and electrical resistance (galvanic skin response or GSR). The polygraph is used as a lie detector by police departments, the FBI, the CIA, federal and state governments, and numerous private agencies. The underlying theory of the polygraph is that when people lie they also get measurably nervous about lying. The heartbeat increases, blood pressure goes up, breathing rhythms change, perspiration increases, etc. A baseline for these physiological characteristics is established by asking the subject questions whose answers the investigator knows. Deviation from the baseline for truthfulness is taken as sign of lying.
There are three basic approaches to the polygraph test:
The Control Question Test (CQT). This test compares the physiological response to relevant questions about the crime with the response to questions relating to possible prior misdeeds. "This test is often used to determine whether certain criminal suspects should be prosecuted or classified as uninvolved in the crime" (American Psychological Association).
The Directed Lie Test (DLT). This test tries to detect lying by comparing physiological responses when the subject is told to deliberately lie to responses when they tell the truth.
The Guilty Knowledge Test (GKT). This test compares physiological responses to multiple-choice type questions about the crime, one choice of which contains information only the crime investigators and the criminal would know about.
Psychologists do not think either the CQT or the DLT is scientifically sound, but a majority surveyed by the American Psychological Association think that the Guilty Knowledge Test is based on sound scientific theory and consider it "a promising forensic tool." However, they "would not advocate its admissibility [in court] in the absence of additional research with real-life criminal cases." One major problem with this test is that it has no controls. Also, unless the investigators have several pieces of insider information to use in their questioning, they run the risk of making a hasty conclusion based on just one or two "deviant" responses. There may be many reasons why a subject would select the "insider" choice to a question. Furthermore, not responding differently to the "insider" choices for several questions should not be taken as proof the subject is innocent. He or she may be a sociopath, a psychopath, or simply a good liar.
Is there any evidence that the polygraph is really able to detect lies? The machine measures changes in blood pressure, breath rate, and respiration rate.
If I was a police officer who was taking part in an interrogation I would create a lie to see if the person was the one
Costanzo, M., & Krauss, D. (2012). Forensic and legal psychology: Psychological science applied to law. New York, NY: Worth Publishers.
It tells us how often we lie or tend to lie under different situations and scenarios by taking real world examples. Kornet explained and analyze the result of various studies by Bella DePaulo, a psychologist at the University of Virginia and her colleagues. As lying and deception becomes an integral part of every individual, it is important to know its impact and its results on our life. We are lying about one or the other thing at almost every moment of our life. It can be at workplace, in a relationship, or even friendship. Kornet concludes this article by saying, “The ubiquity of lying is clearly a problem, but would we want to will away all of our lies? Let’s be honest.” I completely agrees with the author as we have to take a step against lying and deception and to be honest in our lives. Kornet’s article provides really good studies and after analyzing those studies one can think of his/her lying habit and how often he lies in a day. I myself tried and thinking about how many times in a day I lie, and found that I lie a number of times in a day. This article is really interesting and I encourage everyone to read this article. After reading this article, you will come to know the actual truth about lying and its
In “The Interview” by Douglas Starr, He talks about the different techniques they use when interrogating suspects to determine whether the suspect is lying. One technique they use is called the Reid Technique and that is when
One of the last types of ways investigators are coached to detect deception is in the behavioral attitudes of a person being interviewed such as being unconcerned or over anxious (Kassin, 2005). The success rate of looking for these cues are very successful in telling if an individual is being deceitful and has surpassed any laboratory tests conducted on the subject. The laboratory test however did reveal some interesting facts. The research showed that people who had training and experience did not score better than the control group who received no training. In fact all individuals scored at the chance level with the people who had training scored just above chance or at the chance level. To check if special training in the detection of deception was more accurate a study ...
(Kennedy & Haygood, 1992; Williams & Loftus, 1994), which is worrying considering the growing and substantial body of evidence from laboratory studies, field studies, and the criminal justice system supporting the conclusion that eyewitnesses frequently make mistakes (Cutler & Penrod, 1995; Huff, 1987; Huff, Rattner, & Sagarin, 1986; Innocence Project, 2009; Wells, Small, Penrod, Malpass, Fulero, & Brimacombe, 1998). According to a number of studies, eyewitness misidentifications are the most common cause of wrongful convictions (Huff, Rattner, & Sagarin, 1986; Wells et al., 1998; Yarmey, 2003) and, through the use of forensic DNA testing, have been found to account for more convictions of innocent individuals than all other factors combined (Innocence Project, 2009; Wells, Memon, & Penrod, 2006).
Costanzo, M., & Krauss, D. (2012). Forensic and Legal Psychology: Psychological Science Applied to Law. New York: Worth Publishers.
Many of today’s interrogation models being utilized in police investigations have an impact on false confessions. The model that has been in the public eye recently is the social psychological process model of interrogation known as the “The Reid Technique.” There are two alternatives used by the police today to replace the Reid Technique, one is the PEACE Model and the other is Cognitive Interviewing. These methods are not interrogation techniques like Reid but interview processes.
“A good liar uses the truth.” This is a technique used by notorious imposters Frederic Bourdin, and Frank Abagnale. Although Bourdin posed as a child for a second chance at adolescence, Abagnale posed as an adult to gain financial means and respect. Bourdin and Abagnale’s success in deception can be primarily attributed to their careful observation of their surroundings, as well as their ability to detect the emotions of those around them.
One of the main factors in wrongful convictions, tunnel vision, has been recognized by psychologist as a human tendency to quickly convict a suspect so that society feels safe. Although tunnel vision is seen as a natural instinct it can convict innocent individuals and weaken the criminal justice system . Jerome Frank, a judge in the United States Circuit Court of Appeals explored the causes of wrongful convictions and noted that in 36 cases tunnel vision was a significant factor in the conviction of innocent individuals. As demonstrated, tunnel vision is a prevalent factor and may affect cases resulting in judges and juries convicting wrong suspects. However, the human tendency towards tunnel vision is a distinctive feature of an individuals psychological characteristics. Psychologist view tunnel vision as the product of cognitive biases. These natural biases explain why tunnel vision is common even amongst respected legal enforcers and honest justice systems. Although tunnel vision is a common natural tendency, it can be altered and lead to the conviction of innocent individuals.In situations when a high profile case is
Severence, L., Goodman, J., & Loftus, E. (1992). Inferring the criminal mind: Toward a bridge between legal doctrine and psychological understanding. Journal Of Criminal Justice, 20. 107-120.
Although alterations have been made to protect the validity an minimize the error of the polygraph, the results are still dependant of the subjects physiological response. Although research has shown that these alterations do in fact minimize the inaccuracy of the results, no matter what changes are made, there is still a minimal possibility that one can wittingly breach the barriers.
Before proceeding with the review of this article we should first be clear with the meaning of the term forensic neuropsychology. Forensic neuropsychology involves the evaluation of subjects by application of clinical neuropsychological assessment methods. This particular branch of forensic science plays a key role when it comes to evaluating the criminal competency of an individual to stand trial, insanity defences, diminished criminal responsibility, criminal mitigation, etc. A neuropsychological evaluation is an assessment of the cognitive and behavioural functions using a set of standardized tests and procedures, professionals call these sets of tests or procedures as a battery of test. Various mental functions are systematically tested, including, but not limited to:
A polygraph test can record a person's breathing rate, pulse, blood pressure, perspiration and other significant physiological changes that suggest a person is lying, but it should not be used as evidence in a court of law because it does not provide reliable proof of a person's physical reaction to the stress of lying.
Greenfield, D. (2007). Introduction to forensic psychology. issues and controversies in crime and justice. Journal of Psychiatry & Law, 35(2), 201-201-204,105-106.