Polygraphs: How reliable can they be - Essay Example

In this manner, they are usually thought to express guilt even when the subject of the test is professing innocence. Many believe the polygraph to be accurate, especially those who have a financial commitment to employing the technique on individuals (TheftStopper). In addition, the technique is intuitively appealing because of what it claims to measure. The appeal of being able to tell a lie from truth has universal implications, unless it is too good to be true. In fact, there are countless misconceptions about the accuracy and scope of measurement that polygraphs are capable of.

Despite a reputation for being able to cut through verbal responses to measure physiological behaviors, there is no scientific valid measure for ensuring polygraph accuracy and thus is it is not scientifically respected among psychologists or lawyers. Because polygraph testing lacks of validity in its ability to differentiate lies from truths, misconceptions about their effectiveness ought to be dispelled in the public, which is in part the purpose of this paper. A polygraph test is a measurement conducted by an instrument that measures physiological behaviors such as pulse, skin conductivity, blood pressure, and respiration through the duration of an interview.

As a subject is asked questions, the test theoretically measures changes in how the subject responds as a means of differentiating between deceptive answers and truthful answers. When a subject answers a question with very little behavioral response, a recording instrument moves very slightly or not at all outside of the normal range. When a subject answers a question with a heavy behavioral response, that instrument moves outside of the normal range, indicating that the subject became more nervous or responsive to the interrogator during the process.

Verschuere, Meijer and De Clercq (2010) believe this is the result of stress caused by having to answer the question deceptively, as opposed to the ease with which individuals answers questions truthfully. In addition, this assumes that the subject being interrogated is uncomfortable with lying. Nevertheless, Iacono (2001) doubts this from a psychological perspective with respect to the assumption that polygraph subjects will be less nervous in answering control questions. Advocates of polygraph testing claim that, when properly conducted, the test has a 90 to 95 percent rate of validity (TheftStopper).

However, there is sufficient reason to doubt that such testing procedures have any rate of accuracy above chance. One misconception about polygraphs is that they actually measure lies versus truth . The claim that a lie is being detected in a polygraph measurement relies on the assumption that the physiological responses to a question being asked to the subject being tested actually reflect the lie (OTA). While these physiological responses are physical behaviors, a lie is the product of a mental effort and thought process, which makes the connection between the two difficult to define exactly.

For that reason, it is a common misperception that polygraphs tests are actually “lie-detecting tests” by themselves, by objectively teasing apart lie from truth (Iacono). Indeed, the “lie” and “truth” responses on a polygraph have to be interpreted by the test-giver, who is presumably an expert in reading charts produced by the test, which means the test itself is not