Intuitive coding: Vision and delusion

Abstract

We review the hypothesis that the brain uses a generative model to explain the causes of sensory inputs, using prediction schemes that operate based upon assimilation of time-series sensory data. We put this hypothesis in the context of psychopathology, in particular, schizophrenia's positive symptoms. Building upon work of Helmholtz and upon theories in computational cognitive processing, we hypothesize that delusions in schizophrenia can be explained in terms of false inference. An impairment in inferring appropriate information from the sensory input reflects upon the ability to assess the environment and predict outcomes. Although the inference mechanism likely involves both conscious and unconscious processes, we hypothesize that the trigger of delusions may lie within the unconscious neural pathways. A collection of computational predictive codes have been proposed for modeling perception. We discuss two examples, which may be eligible as substrates for intuitive coding. We argue that failure of the psychotic patient to choose the correct computational scheme, or the optimal range of parameters, may readily lead to an altered reconstruction of the object and false inference, feeding into the delusion mechanism. We finally propose using these models in conjunction with cognitive and imaging data, in order to obtain more testable predictions.

• Delusions
• Inference
• Neural Coding
• Paranoid Schizophrenia
• Prediction

Notes

[1] See http://www.gallup.com/poll/16915/three-four-americans-believe-paranormal.aspx. Copyright 2010 Gallup, Inc.

[2] It is also interesting to put this view in the perspective of the Jasperian classification of three delusion subgroups: of perception, of idea or notion, and of awareness (Jaspers, 1913/1997).

[3] The characters from Mircea Eliade's (1971) Noaptea de Sânziene are barely labeled as “psychically-charged” because they feel the “mystic” presence of a car, and anticipate its future disappearance in an accident a year in the future.

[4] Without a good understanding of how these processes are mentally coded, it will never be easy to distinguish between religion as a culture and religiosity as pathology. An interesting recent study (Doerr & Velasquez, 2007) analyzed the content of religious visions/delusions, and concluded that, in mythological narratives, God appears showing his back as departing, while psychiatric patients experience the divinity in a direct way.

Additional information

Notes on contributors

Anca Rădulescu

Anca Rădulescu is an Instructor in the Department of Mathematics at University of Colorado.