Lies! Deceptions! Saw Gerrera used a Bor Gullet to tell if someone was lying to him or not. Unfortunately, afterwards one tends to lose one’s mind.
Bor Gullet was a bit of a strange creature – even for Star Wars. However lie detection has been around for a quite a long time in the real world. Though it’s as much an art as a science, it is pretty consistent in its ability to ferret out lies.
Polygraphs are instruments that determine, through measurement of physical characteristics, if someone is telling a lie or not. It monitors physical changes within the body during a series of questions – some are known to be true in order to establish a baseline. Heart rate, blood pressure, respiratory rate, sweatiness (electro-dermal activity) are all characteristics that can change during a moment of deception.
These changes are involuntary. This forms the basis for the tests’ validity. Deciphering the results can be as much art as science. It requires a skilled and trained examiner to determine the results. However, every person is different so they can only measure relative changes in the body during what amounts to a stressful situation. So they’re not without their draw backs.
Bor Gullet seems like it may be more accurate means of determining deception, though with significantly more collateral damage to the subject.