The term "polygraph" literary means "many writings". The name refers to the manner in which selected physiological data is simultaneously recorded.
Examiners may use pen and ink instruments, also known as analog polygraphs, or computerized instruments. The Cumberland County Sheriff's Office utilizes both instruments.
Polygraph uses specialized data from three signals generated from the human body. First, convoluted rubber tubes that are placed over the examinee's chest and abdominal area record respiratory activity. Second, two small sensors attached to the fingers record sweat gland activity. Finally, a blood pressure cuff, records cardiovascular activity.
Once this data is recorded, a highly trained "polygraph examiner" will determine whether or not the examinee is withholding information or concealing a lie about the answers he/she has provided during the test.
Most law enforcement agencies use polygraph testing on an on-going basis. It is used in criminal investigations to determine whether a suspect is likely to be misleading investigators. It is also used to see if employment applicants who wish to join the Cumberland County Sheriff's Office have been honest about their own past.