Lie detectors are real?!

After years and years of the polygraph machine being featured in great and famed TV shows, it is actually a pretty common belief that these so-called 'lie detectors' are reliable enough to tell, for sure, whether or not a person is lying. But first, what is a polygraph? What does it do? Well, it is a machine that can distinguish a person's blood pressure, pulse, respiration, and skin conductivity (depending on the model, it may detect other things as well). These responses are thought to be directly related to a person's state of mind, hence they're called physiological responses. But, well, there are at least two problems with this.

1. "There is no evidence that any pattern of physiological reactions is unique to deception."  
2. "An honest person may be nervous when answering truthfully and a dishonest person may be non-anxious."

 (www.apa.org)

What this means is that polygraph tests, aren't necessarily accurate. In fact, even "courts, including the United States Supreme Court... *, have repeatedly rejected the use of polygraph evidence because of its inherent unreliability" (www.apa.org). So in reality, polygraph tests aren't conclusive, and don't test for lies, but physical responses which may or may not even be definitively connected with lying.

Verdict: Not Yet

* "cf. U.S. v. Scheffer, 1998 in which Dr.'s Saxe's research on polygraph fallibility was cited"