Theory Behind the Polygraph

The two main sources of evidence relevant to the validity of polygraph testing are basic scientific knowledge about the processes the polygraph measures and the factors influencing those processes and applied research that evaluates the criterion validity of polygraph tests in specific settings. The following are the foundations of the polygraph technique that will help establish the relationship between the responses and the examination on the subject:

• Mechanical Leg Basic Premises The polygraph machine is capable of producing graphical records containing reliable information about physiological changes.
• Physiological Leg Basic Premises Physiological changes that occur automatically only after stimulation of a specific nervous system component
• Psychological Leg Basic Premises The specific nervous system component whose stimulation can thus be diagnosed is thus stimulated by the involuntary mental and emotional processes of the individual who is consciously attempting concealment of deceptions

These are called the Tripod Foundation of the Polygraph Technique.