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INTERNATIONAL POLYGRAPH SERVICES
IRELAND
How Does A Polygraph Work?


The polygraph (popularly referred to as a lie detector) is an instrument that measures and records several physiological responces such as blood pressure, pulse, respiration, and skin conductivity while the subject is asked and answers a series of questions. When conducted by a competent and experienced polygraph examiner, deceptive answers will produce physiological responses that can be differentiated from those associated with non-deceptive answers.
    At the outset, the examiner obtains a complete background information on the case. The polygraph test or examination proper consists of 3 phases.  During the first phase, the pre-test phase, the examiner discusses with the subject the test issue , thoroughly reviews all of the test questions that will be asked during the test,and assesses the subject's emotional and physiological suitability to undergo the polygraph test.

    The testing phase consists of a series of tests where the subject's physiological responses are recorded as the subject answers a set of questions reviewed earlier.  The polygraph theory, is based on psychophysiological principle, is that when the subject hears a question which he or she intends to lie, the brain interpretes and triggers automatic and uncontrollable phsiological changes captured by the polygraph.

    During the post-test phase, the examiner reviews all test data obtained and interprets the polygraph charts, from which the examiner will reach one of 3 conclusions - that the subject is telling the truth; that the subject is not telling the truth; or that the results are inconclusive.  Upon completion of the 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 between 2 to 3 hours.

How Accurate Is The Polygraph Test?

    There are now about 25 research studies available on the accuracy of the polygraph tests.  In 'real life' cases, researchers have found it very difficult to assess the accuracy of polygraph examination because the 'ground truth' criteria are often lacking i.e. it is not possible to find a representative sample with which one can establish with certainty who is and is not actually telling the truth.  Based on the studies now available, experts assess the accuracy of polygraph examinations administered by a competent examiner to be about 90% and with thwe latest training, techniques and equipment up to 98%.  Studies have also shown that the level of skills 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.

    In many ways, seeking a good polygraph examiner is similar to seeking a good surgeon. It pays to get a surgeon with a good track record although you may pay more. Similarly, an examiner with a good track record and reputation increases your probability of success in arriving at the truth and avoid mistakes.

Is the Polygraph Test Result Admissible In Court?

    Although the polygraph test has been in use in the United States for almost a hundred years, this technique is relatively new in UK & Ireland.  There is no court ruling on the admissibility of polygraph evidence in most countries. In the United States, most states permit polygraph test results to be used as evidence where parties have agreed to their admissibility before the examination is given, under the terms of a stipulation.  In one US state, New Mexico, polygraph evidence is admitted in the same way as other scientific evidence.

How Does The Polygraph Test Serve As An Investigative Tool?

    'Smart' offenders commit crimes in such a manner as to cover their tracks and make it difficult to identify the culprit or to prove guilt.  Sophisticated crooks know how the authorities operate and they resort to countermeasures.  In the workplace, the culprit could be one of many staff working in an office but there are no leads.  Such a scenario is typical of many crimes committed.  Routine police investigations in such cases may end in a 'dead end' and the employer winds up having to live with the uncaught offender.  Investigators find themselves in situations where there is a complete lack of information/evidence, information gaps or only circumstantial evidence.  Often, it is a case of one man's words against another.  At other times, different people give grossly different versions of the same event or a person gives an account that cannot be independently verified.  In such situations, the polygraph test is the most effective means to determine the credibility of a person's statement.  It expeditiously and accurately guides the investigators to channel resources in the right direction by exonerating the innocent and narrowing down suspects or identifying the perpetrator.

     In law enforcement scenarios, the interviewer is often faced with a situation where a suspect keeps changing his account and leading the interviewer up the garden path. The polygraph is the most effective tool against such an interviewee. Investigative resources can then be focussed on gathering evidence on the culprit.  Many a times, this leads to the guilty confessing his crime through a combination of skilful interviewing and polygraph testing.

    On the other hand, the polygraph test can also be used for less complex cases like determining the credibility of the statement of a witness, informer,suspect or an accused person in any investigation, or just an individual involved in any dispute, including marital or fidelity issues. Polygraph Services has successfully helped clients to solve cases involving employee theft, commercial fraud, corruption, violent crimes, drug offences, industrial espionage, and threats to corporate security.

    One of the most difficult type of cases to solve is the "inside job" e.g. espionage, collusion between employees and outside criminal syndicates, between employees in different internal departments and between senior and junior staff, terrorist acts committed with insider help etc.

How Does The Polygraph Pre-Employment Screening (Background Check) My Business?

   While most job applicants are honest and hardworking individuals, some of them try to gain a job by misrepresenting their background, employment history, education, experience, and abilities on their resume and application. Many job applicants misrepresent or exaggerate their abilities in their resumes. Consequently, some individuals are hired who eventually put the employer, co-workers, and members of the public at risk because of their inappropriate behaviour.  Many employers do not even institute pre-employment background checks on their employees because they do not realise its importance before it is too late. Some employers rely on perfunctory screening methods like interviewing, checking with characters referees and past employers which are inadequate, especially for positions of trust.  Furthermore, conventional methods for background checks cannot be used to screen foreign employees.

    Even for organisations with access to criminal and other official records, they find that such records are inadequate. For every crime solved, there are many others which remain unsolved or undetected.   It is for this reason that many well-known organisations like CIA, FBI, US Department of Defence and private sector organisations rely on polygraph pre-employment screening.  Polygraph screening often reveals reliable information not obtainable by any other means.  These include concealing/falsifying background information or qualifications, criminal records, undetected crimes like theft from previous employers, fraud, corruption, drug offences, sexual crimes, violent behaviour, membership of undesirable or subversive groups and other unsuitable behaviour. According to a Washington Post news report, the polygraph is a vital component of FBI's security program. The FBI now conducts about 8,000 polygraph tests each year, most of which involve current employees, applicants and contractors. All applicants and new employees undergo a polygraph at the FBI, and nearly every employee -- including the director -- is subject to a new test every five years.
The polygraph test, known popularly as "lie detector test" has been in use in the United States for almost a hundred years.  Recently, US practitioners called it psychophysiological detection of deception or credibility assessment. They all refer to the same thing. Over the last few decades, polygraph tests have proven to be one of the most powerful, robust and useful scientific tools in criminal investigations and personnel screening.  It is routinely used in almost all major investigations in advanced countries employing this forensic tool. Among the most important applications of the polygraph test are counter-intelligence, counter-espionage screening, counter-terrorism and combating corruption. In recent years, polygraph tests are increasingly used for sex offender testing and monitoring.  Prosecutors routinely make use of polygraph tests to decide whether and which legal charges to file.


        It is well publicised that agencies like the CIA, FBI, National Security Agency, US Secret Service and the US Department of Defence etc employ polygraph tests for investigations and screening their own staff and contractors.  There is also widespread use of private polygraph tests on spouses, fiancees, girlfriends, boyfriends etc suspected of cheating brought about or exposed by social networking websites and smart mobile devices. Today, the polygraph test is used in more than 56 other countries world-wide, including , New Zealand, China, Taiwan, India, Malaysia, Indonesia, Philippines, Korea, Japan, Israel, Australia, Canada, Dominican Republic, Mexico, Romania, Russia, Singapore, South Africa, Spain, Belgium, United Kingdom, Colombia, the Middle East etc.  The U.S. with between 3 and 4 thousand active polygraph examiners in the government and private polygraph companies is undoubtedly home to more examiners than any other countries.

  IPS Ireland undertakes extensive polygraph employee screening for local and foreign retail businesses as well as manufacturing industries where, despite tight security measures - theft, corruption, counterfeiting etc commited by employees in collusion with syndicates, pose a serious challenge. Foreign government agencies have also engaged IPS Ireland to assist in their criminal investigation.

Tel: +353 85 176 3360 or 091 483913