You’ve likely never attended an exorcism, but popular culture ensures that you know what one is. Yes, we’re talking the forced removal of a demonic entity from the human psyche, but what else can we glean about this paranormal experience from shamanistic rites of exorcism and the psychological principles of dissociative identity disorder and cognitive dissonance? As 'The Exorcist' creeps in on its 43rd anniversary, Robert and Christian discuss the real and imaginary forces at work in the demon-haunted mind.