that dude who lies...

You can take a whole course on how to detect lies. Some people seem to be naturally good at knowing when someone is lying. Plenty of people use it for their work. Police, investigators, intelligence gathering agencies, psychologists, bosses, attorneys, etc.

http://merciad.mercyhurst.edu/content/intelligence-studies-majors-learn-detect-lies

.

 

Things get even trickier in the arena of detecting lies and psychological tactics. There is the other side of the coin where someone can use tactics on someone else to trick the person into saying things that later can be interpreted as lies and used against the person, even though they aren't factual. Some attorneys are quite skilled with this in the courtroom, as are some police officers and investigators during encounters and interrogations.

A tactic I've seen personally is a cop repeatedly yelling an accusation at someone as if the person is guilty of something when they aren't. The gut reaction of the person on the receiving end of that approach is to defend oneself by stating the opposite of the accusation, which, in reality, may actually be a lie. The truthful statements the person made are ignored and the cop writes down only what he tricked the person into saying. Later, that statement can be used against the person, such as charging the person with lying to a police officer. It may not hold up in court later but it can be used to further detain a person or arrest them for further interrogation.

.