The two-factor framework for explaining delusions is developed in a way that promises reasonable coverage without overgeneralization. We propose that heterogeneity in explanations of delusions can be conceived as parametric variation within the two-factor framework and we suggest several parameters. In three ways, we confront the fact that the second factor in the two-factor framework, a presumed impairment of belief evaluation, has been poorly specified in terms of cognitive function. First, an a priori task analysis suggests that belief evaluation involves working memory and executive processes of inhibition. Second, we review experimental and neuroimaging studies of the belief-bias effect in the context of dual-process accounts of reasoning. The results can be interpreted as supporting the proposal that the second factor in the explanation of delusions is an impairment of working memory or executive function with a neural basis in damage to the right frontal region of the brain. Finally, we present results from a study of cognitive impairments following stroke to support our proposal in the case of anosognosia considered as a delusion.
Chapter. 19656 words. Illustrated.
Subjects: Psychiatry ; Clinical Neuroscience
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