• If you are citizen of an European Union member nation, you may not use this service unless you are at least 16 years old.

  • Stop wasting time looking for files and revisions. Connect your Gmail, DriveDropbox, and Slack accounts and in less than 2 minutes, Dokkio will automatically organize all your file attachments. Learn more and claim your free account.


The Polygraph

Page history last edited by Diana Gukasov 7 years, 11 months ago


"Take hold of his wrists and feel his pulse... a fluttering heart, an unequal pulse, a sudden palpitation shall evidently confess he is the man, in spite of his bold countenance or false tongue." - Daniel Defoe, 1730 




     The polygraph is well known as a lie detector [3]. The polygraph uses vital signs such as respirations, pulse, blood pressure, galvanic skin response (amount of perspiration), and in some muscle contractions to measure the validity of a persons words. The response of the polygraph as the suspect answers questions can create a spike in vital signs, which means that the suspect is lying. There are still arguments on whether the ploygraph is valid or not, but in recent studies there is no proof of its validity. Some agencies still use it as an interrogation object [2]. 

     There were many theories about measuring vital signs to find out if a person was lying, but the first polygraph was invented by John Larson in 1921. Later through the years, the amounts of vital signs have been added to, to try and increase the validity of results [2].  


     Methods of detecting a liar from one who was telling the truth in history was not as easy as connecting the accused to a machine to measure the respirations and pulse. Torture, or as otherwise called "trial by ordeal," was often used in the middle ages. This strategy was created to the thinking that "a higher power" was expected to protect the innocent truth teller from harm [2]. Around the world, ancient Greece, pre-Christian Scandinavia, Iceland, Polynesia, Japan, and Africa believed this was the case. The types of trials ranged from holding ones arms in boiling water to holding hot iron and the guilty would get burnt. China, on the other hand, used a pathophysiological approach to finding a liar. The accused would chew on rice powder and if in the end the rice powder was dry a guilty sentence was placed on the suspect. Saliva, under stress, decreased in amount. Therefore, the act of getting caught can initiate a stress responce decreasing the amount of saliva produced. This process was also used during the inquisition with bread an cheese [2].

     Cesare Lombroso, an Italian criminologist in the late 19th century, created an theory that brought the process of measuring blood pressure during an interview of a suspect [2].

     Vittorio Benussi, during the 20th century came up with 'Benussi ratio' by concluding that a change expiration and inspiration ratio was a clue that the suspect was lying. For this conclusion, Benussi measured blood pressure, pulse, and breathing rate [2].

     Hugo Munsterberg was "the American Pioneer of modern lie detection." His student though, William Marston, in 1915 wrote the "systolic blood pressure deception test." Marston's test required the equipment of a standard blood pressure cuff and a stethoscope. Changes in the systolic blood pressure is what Marston believed to be the "specific lie responce." Marston became the largest advertiser for the lie detector. He created the comic strip Wonder Woman whose power was a lasso that force the person entrapped inside it to tell the truth. He also was on the advertisement of Gillette razors telling the truth about how these razor blades gave the best shave. Also, Marston appeared in Look magazine speaking of the advantages of lie detectors within marriages [2]. 

      John Larson in 1921 was noticed as the man who created "the first modern polygraph instrument." This machine would record blood pressure, pulse rate, and respirations on a piece of paper. Larson became "sceptical of the accuracy and value of the polygraph, particularly in respect of it's use as evidence in court [2]."

     Leonarde Keeler, in 1939, added a galvanic skin response channel to the lie detector and Larson also patented his invention. The galvanic skin response channel measured the concentration of negatively charged chloride ions on the skin due to an increase of perspiration. The reason behind this addition was because a lier was suspected of sweating more that a person that told the truth. The Federal Bureau of investigation (FBI) purchased Keeler's polygraph and was the first instrument used by the FBI [2].

      Joun Reid, in 1945, presented a polygraph that had to deal with muscular activity with blood pressure pulse and respiration recording. He argued that his was more valid [2]. 


       Before the actual questioning of a suspect, there will usually be and initial interview that is referred to as the pre-test. The examiner will talk to the suspect about the procedures of a polygraph, also they will inform the suspect that the polygraph really works and can detect whether a person is lying. This is said to frighten the suspect and force them to tell the truth or raise their vitals when a lie is told. For the innocent, the pre-test might do one of two things. Either the polygraph will make them feel better due to the fact that it will know that they are telling the truth and won't be falsefully convicted, or raise fear in the innocent if the polygraph says that they are lying when in truth they are not [4]. 

     The test questions are commposed of the control question test (CQT) and the Guilty Knoweldge test (GKT). These are the two main types of questions that are asked. The CQT is the test that is usually used during criminal investigations [4]. 

     CQT's are composed of control questions and relevant questions. Control questions are "related to the suspect's crime investigation, but not specifically to the crime [4]."These questions shock the patient and makes it hard for them to tell the truth.Relevant questions are that directly use the crime that the suspect is committed for. After the test is done, the CQT will interpret how these questions compare with eachother [4]. 

     GKT are questions relevant to the crime. "This test measures the suspect's detailed knowledge of a crime that he or she does not want to share [4]." One of the question that a polygraph examiner might as is the weapons that were used. When given a list, the guilty will feel threatened by what is asked and will have a responce on they type of weapon that was used and not for any others. This test is good for when information has not been given to the public about a crime. In most cases, facts about the crime are told to the public so this test is not used as much. A training for investigators is not to give away information that is known about the crime to the suspects that will be questioned [4]. 


     William Marston was largely dedicated for getting his lie detector used in court rooms and when trying a suspect. United States versus Frye was a court case that suspected James Frye, a nineteen year old, of robbery and murder. James Frye confessed to the charges, but later denied taking part in the crime. Marston, in 1938, used his lie detector to test if James Frye was telling the truth; and he was. Marston's test showed that Frye took no part in the crime. Frye in the end was charged and when Marston appealed the charges the court said that the polygraph test did not give enough evidence on wheather Frye was guilty or not. Later, Frye was exonerated and charges for the crime were dropped. From this court case, the 'Frye standard' was made which was a standard for scientific evidence in the US. Polygraph testing was then acceptable in America for the next 70 years [2]. 

     Keeler's polygraph was the first instrument bought by the FBI. Keeler and John Reid also founded schools where one learned how to use and operate a polygraph. The 1940's were an up rise in the use of polygraphs. They were used during criminal investigations and in government agencies. Many German POWs, Nazi members, and sympathisers were uncovered and during 1945 with the use of a polygraph test [2].

     In the 1960's the polygraph was being used all over the United States. 19,000 polygraph examinations were being conducted every year. Not only was the US using the polygraph, but also it had spread to other contries including Japan, China, Israel, and Korea. A polygraph test was used for every part of the professional world. Job interviews used polygraphs to see whether the employee candidates would be a value to the business. In 1965 the idea of screening federal employees caused the Committee on Government Operation to research the first test on the validity of the polygraph [2].  

     During the 1970's, police forces hired a staff of polygraph examiners.This was a multi-million dollar business due to the large amounts of screenings that were done for a person to apply for a job [2].

     The office of Technology Assessments (OTA) in the year 1988 created the Employee Polygraph Protection Act due to the misuse and abuse of the polygraph [2]. "This legislation restricted the polygraph's use withing the private sector, although it specifically exempted federal agencies and public service employees [2]." 

       In 1993, the US Supreme Court's decision in Daubert v. Merrell Dow, Inc appealed Frye standard. This case provided guidelines for the use of scientific evidence withing a court room. 19 states in the US and nine out of the 12 federal circuits still allow polygraph testing [2]. The polygraph is not considered reliable for the use in law enforcement in Europe. Canada uses the polygraph as an investigative tool. Australia and Israel do not allow the use of it in criminal trials. In India, the polygraph is legal if the defendant asks for one [3].   



     The first polygraph validity was conducted by the Committee of Government Operation in 1965. The conclusion was that there was no scientific evidence that the polygraph was valid. "There is no lie detector, neither man nor machine. People have been deceived by a myth that a metal box in the hands of an investigator can detect truth or falsehood [2]." 

     Another study was done by the National Academy of Science (NAS) to review the validity of polygraph testing. The accuracy rates were between 81% and 91%. The conclusions was that "polygraph tests can discriminate lying from truth telling at rates well above chance, though well below perfection [2]."


     There have been many theories that have been said to help a person pass a polygraph test. Aldrich Ames who was a Soviet spy said that all that is needed to pass a polygraph test is "a good night's sleep [3]."

    Other methods that have been proven by spies are self regulation of respiration, deliberately increasing blood pressure by causing pain to oneself or thinking of haunting moments when telling the truth [3]. 


     Implications to media ecology caused by the polygraph is that humans are based on lies. From eating the forbidden fruit and keeping it a secret, to the white lies that a person tells a loved one to protect them. Even though the polygraph has been proven to not be valid, it still uncovers the truth of people. A person becomes the lies that they tell and keeping it up becomes their life. The polygraph, if no countermeasures are used, can break that persons life and expose a person to who they really are. 

     Another implication is for the falsely accused. When the use of a polygraph test was allowed as court evidence it would save many from being wrongfully accused and sent to jail. A person would not be able to live out their life because they are put behind bars. They would spend year to life away from the ones they loved and not see them grow up. A stolen life of an innocent man is a crime in itself. 



[1"Polygraph" Wikipedia, The Free Encyclopedia. 5 December 2012. Wikimedia Foundation, Inc. 29 Nov. 2012 <http://en.wikipedia.org/wiki/Polygraph>

[2] Grubin, Don, and Lars Madsen. "Lie Detection And The Polygraph: A Historical Review." Journal Of Forensic Psychiatry & Psychology 16.2 (2005): 357-369. Academic Search Premier. Web. 29 Nov. 2012.

[3] Smith, N. "Classic Projects: Polygraph." Engineering & Technology (17509637) 7.2 (2012): 112-113. Academic Search Premier. Web. 10 Dec. 2012.

[4]LEWIS, JERRY A., and MICHELLE CUPPARI. "The Polygraph: The Truth Lies Within." Journal Of Psychiatry & Law 37.1 (2009): 85-92. Academic Search Premier. Web. 10 Dec. 2012.

Comments (0)

You don't have permission to comment on this page.