105 學年度學測英文 第 24 題

A polygraph machine, also known as a “lie detector,” is a common part of criminal investigations. The instrument is used to measure 21 a person’s body reacts to questions. The theory underlying it is that lying is stressful, and that this stress can be measured and recorded on a polygraph machine.

When a person takes a polygraph test, four to six wires, called sensors, are 22 to different parts of his body. The sensors pick up signals from the person’s blood pressure, pulse, and perspiration. 23 the process of questioning, all the signals are recorded on a single strip of moving paper. Once the questions are finished, the examiner analyzes the results to determine if the person tested 24 truthful.

Well-trained examiners can usually detect lying with a high degree of 25 when they use a polygraph. However, because different people behave differently when lying, a polygraph test is by no means perfect.