Suppose you come out from home and see a dead dog on the ground.
So when you write a novel, in order to dramatize or create a certain atmosphere, "I came out of my house today and saw a dead dog on the ground." The dead dog looks motionless. My eyes suddenly turned when I passed by. "
The author may have interviewed mental patients (there is no evidence that he has, so it can only be possible).
He reprocessed what he heard or what he thought. The so-called handling is the above-mentioned "exaggerated fiction" plot, which is not a real thing.
If you read the introduction yourself, you will be confused and think it is an interview, which must be true.
Actually, interviewing is one thing, and writing is another.
Halfway through this book, I feel a lot of traps and psychological hints, and people who like to get to the bottom of it are easily influenced.