There have been several reviews of polygraph accuracy. They suggest that polygraphs are accurate between 80% and 90% of the time. This means polygraphs are far from foolproof, but better than the average person's ability to spot lies, which research suggests they can do around 55% of the time.

How accurate are polygraph tests 2020?

Despite claims of 90% validity by polygraph advocates, the National Research Council has found no evidence of effectiveness. ... The American Psychological Association states "Most psychologists agree that there is little evidence that polygraph tests can accurately detect lies."

Can a lie detector test be wrong?

The accuracy (i.e., validity) of polygraph testing has long been controversial. An underlying problem is theoretical: There is no evidence that any pattern of physiological reactions is unique to deception. An honest person may be nervous when answering truthfully and a dishonest person may be non-anxious.