The term "polygraph" literally means "many writings." The name refers to the manner in which selected physiological activities are simultaneously recorded. Polygraph examiners may use conventional instruments, sometimes referred to as analog instruments, or computerized polygraph instruments (CPS).
According to the various state licensing laws and the American Polygraph Association's Standards and Principles of Practice, polygraph results can be released only to authorized persons. Generally those individuals who can receive test results are the examinee, and anyone specifically designated in writing by the examinee, the person, firm, corporation or governmental agency which requested the examination, and others as may be required by due process of law.
Prohibitive Inquiries - Personal and intrusive questions have no place In a properly conducted polygraph examination. Many state licensing laws, the Employee Polygraph Protection Act, as well as the American Polygraph Association, has so stated in language similar to the following:
False positive, False negative - While the polygraph technique is highly accurate, it is not infallible and errors do occur. Polygraph errors may be caused by the examiner's failure to properly prepare the examinee for the examination, or by a misreading of the physiological data on the polygraph charts. Errors are usually referred to as either false positives or false negatives. A false positive occurs when a truthful examinee is reported as being deceptive; a false negative when a deceptive examinee is reported as truthful. Some research indicates that false negatives occur more frequently than false positives, other research studies show the opposite conclusion. Since it is recognized that any error is damaging, examiners utilize a variety of procedures to identify the presence of factors which may cause false responses, and to insure an unbiased review of the polygraph records; these include:
One of the problems in discussing accuracy figures and the differences between the statistics quoted by proponents and opponents of the polygraph technique is the way that the figures are calculated. At the risk of over simplification, critics, who often don't understand polygraph testing, classify inconclusive test results as errors. In the real life setting an inconclusive result simply means that the examiner is unable to render a definite diagnosis. In such cases a second examination is usually conducted at a later date.
The three segments of society that use the polygraph include law enforcement agencies, the legal community, and the private sector. They are further described as follows:
A typical polygraph examination will include a period referred to as:
In the pre-test, the polygraph examiner will complete required paperwork and talk with the examinee about the test. During this period, the examiner will discuss the questions to be asked and familiarize the examinee with the testing procedure.
On December 27, 1988, the Employee Polygraph Protection Act (EPPA) became law. This federal law established guidelines for polygraph testing and imposed restriction on most private employers. EPPA is a federal US law and is therefore not applicable to European or other countries.
This legislation only affects commercial businesses. Local, State and Federal governmental agencies (such as police departments) are not affected by the law, nor are public agencies, such as a school system or correctional institution. In addition, there are exemptions in EPPA for some commercial businesses. These are: