Answered Jul 10, 2019
They don’t necessarily “convince themselves their lies are true”.
The mechanism seems to be…
“I want you to do, give, or tolerate Such-And-Such-Thing, And think that a certain claim will induce to to so, if you believe it. So I will push that at you”.
It is important to note that, sometimes, the thing they want is control. Many, many people feel a lack of control over their lives. Some will desperately look for control opportunities, even those that don’t actually benefit them.
If they lie, and you believe them, then they can feel control. Even if they don’t benefit in any practical or tangible way. Some will lie to manipulate (“Oh, I love you”), including lashing out to induce you feel bad. There are actually people who will claim to hate you, when they really don’t have any opinion of you, at all.
They often have poor ability to predict whether the lie will work. Or whether lying will reduce your future willingness to believe them.
Some will do an approach of multiple different angles. Where, the first lie doesn’t work, and then they move on to the next lie (which might even contradict the first). Hoping to find the lie that you will believe.
Their perception of whether their lies are true, just isn’t on the radar. It is about saying some words, to expect a certain result. The pathology is the failure to realistically expect a connection between the words (lies) and your response/actions.
Users of stimulant drugs (cocaine, amphetamine) are notorious for constant, compulsive lying. I wonder if some non-using liars have some kind of natural brain chemistry similar to that induced by those drugs.