What is the most important factor in the use of a polygraph?

The most crucial factor in the use of a polygraph is the examiner. The examiner's expertise, training, and experience are essential in interpreting the physiological responses recorded during the polygraph test. A skilled examiner is equipped to properly conduct the test, establish a rapport with the subject, and accurately analyze the collected data to determine its validity. The examiner plays a pivotal role in ensuring that the test is administered according to proper protocols and that the results are interpreted within the correct context.

While other factors, such as the make of the instrument, environmental conditions, and the time of day, can have some influence on the outcomes of a polygraph examination, they do not carry the same weight as the examiner's proficiency. An experienced examiner can often mitigate the effects of varying environmental factors or even suboptimal equipment performance, whereas a less skilled examiner may produce unreliable results regardless of the quality of the polygraph machine or other conditions. Thus, the examiner's role is foundational to the effectiveness and reliability of polygraph testing.