how does a Judge know if you are lying?

The court in Mitondo v. Mukasey, 523 F.3d 784, 789 (7th Cir. 2008) said that a liar has a tendency to not give lots of details. The more information you give, the greater are the chances that some of it could be determined later to be false. "As a result, liars tend to say less, and to provide fewer details."

And also, liars tend to distance themselves psychologically from their falsehoods, and so they tend to include fewer references to themselves, and their feelings, in their stories.

A liar might say, "the guard hit me." A truth-teller might say, "The guard reminded me of my high school math teacher. When he grabbed his club, I knew he was going to hit me. I feared he would break my glasses. After he hit me, I felt blood on my neck. I felt dizzy; I hoped he would not hit me on my eyes."

What thoughts went through your mind? [as the guard entered the room]. this is an easy question for the truth-teller to answer.

Truth-tellers have normal amounts of memory failure. They know they have forgotten a few details, and are happy to admit it. Liars, however, develop super memories and claim to remember the smallest of details.