Engineering360: "Researcher developing first online polygraph test"

Too easy to train yourself to avoid detection once you understand how the algorithm works.

Trying to modify innate physiological responses is more difficult. Even a full up polygraph depends in large part on the skills of examiner in concert with the telemetry from the measuring equipment. The process of designing baseline questions is fraught with ambiguity because typically those baseline questions are rather innocuous, so the responses will be different than a 'charged' question in which the question itself generates a physiological response in the examinee.