system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do polygraph tests tell the difference between a lie and genuine anxiety?

Like - if it's based on a person's physiological responses, isn't it possible that a response to a question like "did you murder your hamster" would register as a lie due to the increase in heart rate and blood pressure cause of anxiety associated with being accused of something?
gpt
They don't.

According to the American Psychological Association, “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.”

It has never actually been shown in a controlled test that a polygraph machine can detect lies. Even the creator of the machines stated that they were bunk. They're purely a prop for interrogators.