How do you know if your child has a psychological disorder?

I think he is just seeking more attention or reurance. You kind of suggest this in your note. Obsessive compulsive personality disorders would manifest earlier than 8 years old. I have a goddaughter who mentioned that she was "tall" for an entire year. That is sometime ago, and she is more like a hippie than an OCDer. In fact, I wish seh did have some disorder to better explain her indifferent attitude. But, contrast, I am of the opinion that your "thinking chair" is revealing of a serious minded parent who has son who has simply thought of this vehicle "confessions" to gain attention he would still like. Remember he is 8. But, he is also 12 and 4 years old in some arenas of his life. Maybe, he will be entering spelling test year of school this fall? He can get a pat on the back by spelling all the words correctly. I really think your concern is a little premature. He is just a bit "full of himself" and has a creative mind for making his "transgressions" into very important matters to be discussed. Give him a few weeks and a return to school to become his old self.