Who is the narrator, can she or he read minds, and, more importantly, can we trust her or him?
Third Person (Omniscient)
Want to read people's minds? Everyone's minds? Read a novel written in this point of view.
Not many novels are written in third person omniscient these days, because modern readers seem to like focusing exclusively on the protagonist's point of view. It's certainly easier, and you feel less jerked around. However, there's a lot to be said for third person omniscient. For starters, you don't have to guess how other characters are feeling or reacting.
This choice is especially important for a novel about mental illness. We get in Dr. Fried's head a lot, for example, which is helpful, because she muses about Deborah's case when she's alone.
If we were only in Deborah's head all the time, then it would be more difficult to determine what's real and what isn't. We'd have an unreliable narrator for everything. On the other hand, if we were only in Dr. Fried's mind, then everything would be skewed in the other direction, and we wouldn't be able to see, for example, how scared Deborah is.