Polygraph Tests on the Increase in Jamaica
Polygraph tests have become popular especially as more televised crime dramas show polygraph machines making their mark across charts to detect lies and truths. And, last year, a polygrpah centre was opened at the National Police College, Twickenham Park, St Catherine.
A polygraph is a complex psycho-physiological process, which requires integration between a standard polygraph apparatus, a trained polygraph expert and a complete examination procedure. According to Robert Graham, senior polygrapher and investigator at Guardsman Elite, even the term "lie detector," used to refer to polygraph testing, is a misnomer.
So-called "lie detection" he said involves inferring deception through analysis of physiological responses to a structured, and sometimes non-standardised, series of questions. Graham who joined Guardsman Elite in 2003 as a security specialist became a polygrapher at Guardsman Elite when the decision was made to stop utilising the services of an external examiner.
Over the years polygraph testing has generated considerable scientific and public controversy. Most psychologists and other scientists agree that there is little basis for the validity of polygraph tests. However, according to Graham, great care and patience are exercised when conducting this kind of examination, which has led to a 96 per cent success rate on specific tests and a little less accuracy on pre-employment tests.
Graham said prior to conducting an examination, in phrasing the questions to be examined, a professional polygraph examiner must obtain as detailed as possible background material for the examination. "This background material will be of great assistance to the expert during the examination. Optimal phrasing of the examination questions is one of the most important components of the examination," he said.
He said a standardised polygraph examination is conducted in a quiet room, sealed against external noises as much as possible. At the beginning of the examination, there is an introductory discussion, during which the respondent is asked questions aimed at receiving information on their mental and physical health situation in order to determine the degree of their suitability and competence to undergo a polygraph examination.
"The questions in a polygraph examination have to be as simple, clear and concise as possible. Questions with ambiguous answers should be avoided respondents have to answer the questions solely in the positive or negative. No questions which the respondent refused to answer should be asked.
Graham notes that certain logical responses regarding a specific questions, which are repeated a number of times, will lead to the conclusion that the respondent is not speaking the truth.
"In a normal setting the respondent's sweating, breathing and blood pressure are recorded. These findings are not used in the assessment. However we look to see if there are any significant changes outside of the norm when certain questions are asked," he said.
Graham said the average test including a pre-test interview lasts for about 90 minutes. He said for investigative purposes, polygraph tests are used as a tool in the investigation and should never be used alone to determine the outcome of a case.