A polygraph test sometimes known as a ‘lie detector test’ is an examination procedure used to detect lies. This test is done using a machine known as a polygraph. It registers the body’s involuntary responses to an interrogator’s questions. This in turn ascertains the deceptive behavior of the individual being examined (Kozel, Padgett & George, 2004).
Usually, the polygraph test assesses three parts of a human beings system. A forensic Psych physiologist usually analyses several moving lines from a computer, which shows the behavior of the body responses. These lines always differ depending on the emotional reaction of the individual to the questions. Polygraphs are commonly used in criminal investigations, but nowadays government bodies as well as organizations use polygraphs on their potential employees.
The first lie detector was invented in 1917 by William M. Marston. In 1923, the struggle to reveal verbal deception through observation on systolic blood pressure was stopped by courts. The D.C court of appeals stated that Marston’s lie detector machine did not give sufficient scientific support. Marston’s invention shed light to the invention of a more advanced polygraph in 1921 by John Augustus Larson.
However, this medical student from the University of California got a helping hand from a police officer who was based in Berkeley Police Department in California. Since that time many devices have been made. An example is Berkeley Psychograph which is a blood pressure recorder that was made by C.D Lee later in 1936 and the Darrow Behavior Research photograph developed in 1941. John Reid came up with a device in 1945. It documented any energetic activity.
The fundamental idea of using the polygraph is to detect lies. This ideology is feasible since when someone is cheating, there is always a tendency to become measurably nervous. It has been argued that polygraphs are reliable if well-trained polygraph examiners are used to carry out the procedure. This is because a highly trained polygraph examiner is an expert in both interrogation and technical operation. These qualifications together with experience enable the polygraph examiner to detect the truthfulness of an individual.
A recent survey carried in Michigan State, showed that a great number of agencies using polygraphs support its use since it discloses information that cannot be got by any other methods. The survey also shows that background information can be established easily when polygraphs are used to examine individuals and these therefore deters undesirable interviewees. Additionally, the survey also shows that it is a quicker means of selection.
Polygraph testing has however been criticized by many people in U.S.A. This makes polygraph testing a controversial matter between the government agencies and the public. Several human rights societies among other institutions argue that polygraph testing can be a source of tremendous anxiety.
It is therefore possible individuals hiding nothing may fail the test. Furthermore, polygraph examinations are interrogations that can scare innocent people who end failing them for no apparent reason. This results into denial of justice and even employment for organizations which use this kind of selection method.
Polygraph testing is essential in the law enforcement arena; the procedure can help the authorities achieve their goals in handling cases by carrying out productive interrogations. Polygraphs are accurate since subjects who believe that the device is perfect would rather confess than wait for the device to ‘detect the truth’. It is also common for people lying to show the same physiological behavior and vice versa. The test may therefore give desired results and help in the smooth running of law enforcement. It is argued that unless someone is a trained and experienced criminal, a polygraph test evaluation may expose him or her.
He continues to argue that since an individual undergoes the test twice or less in his life, it is hard for him to lie but instead say the truth. Polygraph tests deliver facts than lies in the course of an interrogation. Provision of useful information is consequently achieved. Bar-Hillel and Ben-Shakhar assert that many people who expect to be tested would prefer saying the truth than to be embarrassed on their dishonesty (p.78).
Polygraph testing is known to provide little basis for accuracy and should not be heavily relied on. Other supporting selection methods should be included in examinations. This would in turn yield the required results. Physiological responses analyzed by polygraphs can at times reflect the opposite of the real scenario due to many factors that may be having adverse effects on the subject. For instance, health factors control the human body.
If at all an individual is sick, it is possible that there may be an interference with their body’s normal functioning. This is bound to give wrong signals during a test. Polygraphs should not be used in future since physiological responses measured by the tests are never uniquely correlated with deception. Some responses can consciously be controlled and in turn have an effect on the polygraph measures.
Bar-Hillel, M. & Ben-Shakhar, G. (1986). The Prior Case against Graphology. In B. Nevo (Ed.), Scientific Aspects of Graphology (pp.76-80).Chicago: Charles C.Thomas
Kozel, F.A., Padgett, T.M. & George, M.S. (2004). A Replication Study of the Neural Correlates of Deception. Behavioral Neuroscience. London: Prentice Hall.