Polygraph machines sense changes in glucocorticoid (hormone) levels, which initiate chemical reactions such as changes in respiration, heart rate and skin conductance (a moisture buildup under skin). Thus, a polygraph measures physiological changes when under the stress of questioning. That questioning is intended to determine whether a person is lying or being truthful. EyeDetect measures changes in pupil size and eye movements that reflect the changes in their brain activity while a person reads and responds to a questionnaire.
For the polygraph, the primary testing premise is that a deceptive person will show stronger emotional reactions to questions about topics for which they are deceptive. For EyeDetect, the primary testing premise is that a deceptive person will show an increase in cognitive load when questioned about topics for which they are deceptive.
