Rethinking the Ipseity Disturbance Theory of Schizophrenia Through Predictive Processing

This paper takes a fresh look at Sass & Parnas’ Ipseity Disturbance Hypothesis about Schizophrenia. It asks how well the current theorization in terms of hyperreflexivity, disturbed self-presence and diminished grip really explain the phenomenology of schizophrenia. It then turns to a detailed discussion of the way the various elements of ipseity disturbance are supposed to be explained finding there are certain gaps in that explanation. The second part discusses how the new Hierarchical Predictive Processing (HPP) framework can do a good job explaining and inter-relating the three factors in ipseity disturbance: first, distortions of presence; second, hyperreflexivity; and third, why some distortions of presence progress to the positive symptoms of schizophrenia, namely hallucination and especially delusions. The paper argues that really moving toward a deep understanding of schizophrenia requires grounding the theory in a mechanistic explanation. HPP is well-poised to play this role by explaining why distortions of presence might lead to hallucination and global changes in the structure of a patient’s beliefs.