After realizing how inaccurate polygraph testing is, I am confused why in some states it is still Admissible in court?

dc585 wrote on Jan 27^th, 2017 at 3:23pm:


Probably for the same reason that its use is mandated by probation/parole authorities and required of registered sex offenders in  many states. 

Polygraph measure physical response from the body. It does not read the mind. I know for a fact that I can have huge physical response to a question and absolutely not be lying.
Could it detect a lie ? Yes, of course, but just because there was a physical response to a question does not always mean it was triggered by a lie. I would give it 50/50 at best, but it would really depend on the situation of course. More data to take into consideration than is.
Frightening stuff.

Ex Member wrote on Feb 1^st, 2017 at 5:01pm:


The polygraph instrument is sensitive to fluctuations in breathing, perspiration, blood pressure, and heart rate, but there is considerable doubt about polygraphy's sensitivity as a lie test because the physiological indices measured by the polygraph haven't been shown to be systematically correlated with lying or truth-telling. As Dr. Alan P. Zelicoff put it, "From a medical and scientific standpoint, it is not sufficient to measure well that which should not be measured in the first place."

George W. Maschke wrote on Feb 2^nd, 2017 at 8:17am:

Lying is more cognitively demanding than telling the truth. This, in most people, will generate some set of physiological reactions just as mental countermeasures do. But a slab of marble also contains the David, the trick is to remove the unwanted particles.