A predictive coding account of OCD

This paper presents a predictive coding account of obsessive-compulsive disorder (OCD). We extend the predictive coding model to include the concept of a 'formal narrative', or temporal sequence of cognitive states inferred from sense data. We propose that human cognition uses a hierarchy of narratives to predict changes in the natural and social environment. Each layer in the hierarchy represents a distinct view of the world, but it also contributes to a global unitary perspective. We suggest that the global perspective remains intact in OCD but there is a dysfunction at a sub-linguistic level of cognition. The consequent failure of recognition is experienced as the external world being 'not just right', and its automatic correction is felt as compulsion. A wide variety of symptoms and some neuropsychological findings are thus explained by a single dysfunction. We conclude that the model provides a deeper explanation for behavioural observations than current models, and that it has potential for further development for application to neuropsychological data.