Lie Detector Test | Polygraph Los Angeles, Agoura HillsHover View Investigations now offers Polygraph and Lie Detector Tests
The polygraph test, more commonly known as the "lie detector test," has been in use in the United States for almost a hundred years. It has been called a "psychophysiological detection of deception" or a "credibility assessment," but the terms all refer to the same thing. With the advances in technology, polygraph tests have proven time and again to be one of the most powerful and useful scientific tools in both personnel screening and criminal investigations.
It has become a routine part of almost all major investigations in countries around the world that employ this forensic tool. Polygraph tests are used to help protect us every day as they are among the most important applications of counter-intelligence, counter-espionage screening, counter-terrorism and combating corruption. Polygraph tests have also become increasingly popular for sex offender testing and monitoring.
The use of private polygraph tests has also become widespread on spouses and lovers suspected of cheating thanks to social networking websites and smart mobile devices among other things. Today, the polygraph test is used in more than 68 other countries world-wide.
How do polygraph tests work?
A polygraph test measures and records several physiological indices such as blood pressure, pulse, respiration, and skin conductivity while the subject is asked and answers a series of questions. If done by a competent and experienced polygraph professional, deceptive answers should produce physiological responses that can be differentiated from those associated with non-deceptive answers.
To start, the examiner will obtain complete background information on the case. The polygraph test itself consists of three phases. The first phase, or pre-test phase is where the examiner will discuss the test issue with the subject, thoroughly review all test questions to be asked during the test, and assess the subject's emotional and physiological suitability to undergo the polygraph test.
During the testing phase, the subject goes through a series of tests where their physiological responses are recorded as they answer a set of questions reviewed earlier. The theory behind the polygraph is based on a psychophysiological principle. When the subject hears a question where they plan to lie, the brain interprets and triggers automatic and uncontrollable physiological changes captured by the polygraph.
At the post-test phase, the examiner will review all test data obtained and interpret the polygraph charts. There will be one of three conclusions in which the examiner will reach:
- The subject is telling the truth
- The subject is not telling the truth
- The results are inconclusive
Upon completion of the polygraph test, a verbal report will be given to the client, followed by a written report which consists of a synopsis of the case information, a list of the relevant test questions, the subject's answers, and the examiner's opinion as to the subject's truthfulness or deception.
Polygraph tests are strictly voluntary in nature and do not violate a subject's human rights. Each polygraph test normally lasts from one and half to two and a half hours.
How do polygraph tests work?
There are now more than 25 research studies available on the subject of the accuracy of polygraph tests. In "real life" cases, research has shown that it is extremely difficult to assess the accuracy of a polygraph examination because the "ground truth" criteria are often lacking. The issue arises in that it is not possible to find a representative sample in which it can be established with certainty whether or not the subject is or is not actually telling the truth.
However, based on the studies now available, experts state that the accuracy of polygraph examinations administered by a competent examiner to be about 90%. Level of skill and experience of the examiner plays an important part in the accuracy of the examination. Comparative studies have shown that polygraph tests yield an accuracy that equals or exceeds that of many other forms of evidence. In one study, it was shown that polygraph tests produced an accuracy that was comparable to results obtained by document examiners and fingerprint analysts, and exceeded that of eyewitnesses.
Can an "innocent" person fail a polygraph test due to nerves?
It is quite common for the test subject, whether innocent or guilty, to feel nervous during a polygraph test, especially if it is their first experience. It is no different from a taking a big school exam or a job interview. However, when the test is administered by a competent and experienced polygraph professional, the test should not be affected by nerves. There are certain testing protocols built into the process to take care of nervousness.
Can a polygraph test be beaten?
If the test is conducted by a competent polygraph professional, there is no technique or knowledge that will help the test subject affect the test results. Over the years, many lie detector tests have been conducted on subjects who were trained in the technique and the results turned out to be no different from an ordinary man on the street.
Who uses a polygraph test?
At the federal level alone, the polygraph is used extensively in counter-intelligence, counter-terrorism, and counter-narcotics programs in addition to criminal investigations, intelligence operations, presidential protection and nuclear materials containment. As stated above, there are at least 68 countries world-wide where the polygraph is used for similar applications. The FBI, CIA, U.S. Secret Service and the National Security Agency are just some of the government agencies which use polygraph testing for a variety of subject matters and issues.
In the private sector, polygraph is used extensively by individuals, families, therapists, attorneys, courts, business and many other entities. Just some of the entities which use polygraph testing are:
- Private Individuals
- Police and Fire Departments
- Families and Teen agers
- High Schools and Universities
- Commercial Businesses
- Financial Institutions and Banks
- Therapists and Counselors
- Investigative and Detective Agencies
- Law Firms and Courts of Law
- Government Agencies and Institutions
- Department of Children and Family Services
- National Television and Radio Stations
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