Polygraph tests, also known as “lie detector tests,” are commonly used in criminal investigations and background checks. The machine measures physical responses to questions, such as heart rate and perspiration. However, the accuracy of the test is controversial and can be cheated with proper training.
Also known as a “lie detector test,” a polygraph test isn’t something out of the movies. Polygraphs are a common part of criminal investigations and background checks. More and more companies, especially government agencies, are now requesting these tests from prospective employees.
A polygraph is a simple machine made up of six sensors or “wires” that are connected to the person taking the test. The examiner, known as a forensic psychophysiologist (FP), observes a moving sheet of paper and the type of lines drawn on it by a special pen. These lines vary according to the subject’s emotional reaction to the questions, and these signals are recorded on paper.
Despite what the name suggests, a polygraph test does not detect lies, but rather evaluates a subject’s physical responses to a series of questions. To do this, he assesses the subject’s heart rate, respiratory rate, blood pressure, and perspiration on his fingertips. Sometimes, a polygraph also evaluates involuntary arm and leg movements and nervous tics, which are often detected during difficult questions. Generally, when a person lies, their heart rate increases, they begin to sweat, and their whole body reacts. This is what the test measures.
Before a polygraph test begins, the examiner and the person taking the test will have a ‘preliminary interview’. During this time, the examiner will explain how the test works and go over the questions to ask. In case of legal matters, a lawyer is usually present during this phase. During the actual test, the examiner asks a mix of irrelevant questions, such as “What’s your name?”, and questions that are directly related to the problem being tested.
There is a good deal of controversy surrounding lie detector tests, as anyone can learn to cheat on them with the proper training and preparation. While the results of a polygraph test can be used in court, many organizations are now fighting to abolish the practice because it may not be 100% accurate.
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