Thoughts, Delusions and Beliefs Theories of delusion formation can be roughly divided into more perceptual vs cognitive accounts. The perceptual account proposed by Brendan Maher and others posit that delusions are natural product of rational explanation of abnormal sensory experiences. Cognitive accounts take a more top-down approach and point to the roles of cognitive biases, abnormal hypothesis testing, and “jumping to conclusions" in delusion formation (e.g., Helmsley, Bentall, Garety, David). Interacting with cognitive and perceptual theories, are the motivational and emotional factors (e.g. Freud, Bentall). Delusions are rarely non-emotional and may often reflect projections of unconscious unresolved conflicts to external targets or attempts to protect self. There are also hybrid models such as the two process theory (Langdon, Davis) and similarly, the jump-to- perception-and-conclusion theory (Fleminger). While delusions held by individuals with psychosis do not necessarily have specific neuroanatomical correlates, there are neurological lesion cases that offer fascinating insight into specific delusions. Delusional misidentification syndromes, autoscopic phenomena, paranormal beliefs have been studied extensively in lesion patients (Brugger). Last but not least, there are sociocultural and ecological influences on delusion formation (see Van Os). We study the possible interactions between in pattern recognition and personality traits as major factors in delusion formation. Our studies of biological motion perception, eye gaze direction perception and other perceptual tasks suggest that increased false alarm rates (seeing something where there is none) may be related to the presence of delusions. This may be due to too much top-down control, poor quality sensory data and an interaction between the two. Noisy input from abnormal sensory systems necessitate increased top-down, cognitive processing, which may then lead to faulty conclusions. Over time, these experiences may result in an accumulation of inaccurate information and probabilities about the world (see Control of mental represenatations). We are currently investigating visual and auditory detection of living and nonliving stimuli in relation to delusion formation in healthy individuals and psychosis patients (see Neuocognitive origins of social deficits) Read the summary of a workshop on delusions held at the International Congress on Schizophrenia Research in San Diego, March 2009 here. Thakkar_ICSRReport.pdf |