Folie à deux is the transference of delusional ideas from one 'primary' individual to one or more 'secondary' individuals (Lasègue & Falret, 1877). However, it is difficult to investigate experimentally because often only one patient is identified as delusional. We investigated whether hypnosis could model the experiences of the secondary in this delusion. Our primary was a confederate, who displayed two delusional beliefs and attempted to transmit them to hypnotised subjects. We manipulated the status of the confederate so that they (...) were portrayed as either "credible" or merely "interesting". Many high hypnotisable individuals adopted the confederate's beliefs and confabulated evidence in support of them. Also, subjects who interacted with a credible confederate extended their delusions beyond those displayed by the confederate. We discuss the strengths and limitations of this approach and suggest ways to improve the validity of this model. (shrink)

The impact of our desires and preferences upon our ordinary, everyday beliefs is well-documented [Gilovich, T. . How we know what isn’t so: The fallibility of human reason in everyday life. New York: The Free Press.]. The influence of such motivational factors on delusions, which are instances of pathological misbelief, has tended however to be neglected by certain prevailing models of delusion formation and maintenance. This paper explores a distinction between two general classes of theoretical explanation for delusions; the motivational (...) and the deficit. Motivational approaches view delusions as extreme instances of self-deception; as defensive attempts to relieve pain and distress. Deficit approaches, in contrast, view delusions as the consequence of defects in the normal functioning of belief mechanisms, underpinned by neuroanatomical or neurophysiological abnormalities. It is argued that although there are good reasons to be sceptical of motivational theories , recent experiments confirm that motives are important causal forces where delusions are concerned. It is therefore concluded that the most comprehensive account of delusions will involve a theoretical unification of both motivational and deficit approaches. (shrink)

Current models of delusion converge in proposing that delusional beliefs are based on unusual experiences of various kinds. For example, it is argued that the Capgras delusion (the belief that a known person has been replaced by an impostor) is triggered by an abnormal affective experience in response to seeing a known person; loss of the affective response to a familiar person’s face may lead to the belief that the person has been replaced by an impostor (Ellis & Young, 1990). (...) Similarly, the Cotard delusion (which involves the belief that one is dead or unreal in some way) may stem from a general.. (shrink)

On one influential view, the problems that should attract medical attention involve a disorder, because the goals of medical practice are to prevent and treat disorders. Based on this view, if there are no mental disorders then the status of psychiatry as a medical field is challenged. In this paper, I observe that it is often difficult to establish whether the problems that attract medical attention involve a disorder, and argue that none of the notions of disorder proposed so far (...) offers a successful demarcation criterion between medical and non-medical problems. As an illustration, I consider why delusions are considered pathological and whether they attract medical attention in virtue of being pathological, where ‘pathological’ stands for ‘being caused by a disorder’. Although there are several promising answers to what makes delusions pathological, available accounts of the pathological nature of delusions fail to distinguish delusions from other irrational beliefs that are not typically thought of as pathological; and cannot explain why delusions typically attract medical attention whereas other irrational beliefs do not. (shrink)

Naive physics beliefs can be systematically mistaken. They provide a useful test-bed because they are common, and also because their existence must rely on some adaptive advantage, within a given context. In the second part of the commentary we also ask questions about when a whole family of misbeliefs should be considered together as a single phenomenon.

The present study assessed the degree to which probabilistic reasoning performance and thinking style influenced perception of risk and self-reported levels of terrorism-related behaviour change. A sample of 263 respondents, recruited via convenience sampling, completed a series of measures comprising probabilistic reasoning tasks (perception of randomness, base rate, probability, and conjunction fallacy), the Reality Testing subscale of the Inventory of Personality Organization (IPO-RT), the Domain-Specific Risk-Taking Scale, and a terrorism-related behaviour change scale. Structural equation modelling examined three progressive models. Firstly, (...) the Independence Model assumed that probabilistic reasoning, perception of risk and reality testing independently predicted terrorism-related behaviour change. Secondly, the Mediation Model supposed that probabilistic reasoning and reality testing correlated, and indirectly predicted terrorism-related behaviour change through perception of risk. Lastly, the Dual-Influence Model proposed that probabilistic reasoning indirectly predicted terrorism-related behaviour change via perception of risk, independent of reality testing. Results indicated that performance on probabilistic reasoning tasks most strongly predicted perception of risk, and preference for an intuitive thinking style (measured by the IPO-RT) best explained terrorism-related behaviour change. The combination of perception of risk with probabilistic reasoning ability in the Dual-Influence Model enhanced the predictive power of the analytical-rational route, with conjunction fallacy having a significant indirect effect on terrorism-related behaviour change via perception of risk. The Dual-Influence Model possessed superior fit and reported similar predictive relations between intuitive-experiential and analytical-rational routes and terrorism-related behaviour change. The discussion critically examines these findings in relation to dual-processing frameworks. This includes considering the limitations of current operationalisations and recommendations for future research that align outcomes and subsequent work more closely to specific dual-process models. (shrink)

Contemporary experimental research has emphasised the role of centrally generated signals arising from premotor areas in voluntary muscular force perception. It is therefore generally accepted that judgements of force are based on a central sense, known as the sense of effort, rather than on a sense of intra-muscular tension. Interestingly, the concept of effort is also present in the classical philosophy: to the French philosopher Maine de Biran [Maine de Biran . Mémoire sur la décomposition de la pensée , Vrin, (...) Paris ], the sense of effort is the fundamental component of self-experience, the landmark of the exercise of the will. In the present review, after a presentation of the nature and neurophysiological bases of effort sensation, we will examine its possible involvement in the neurocognitive process of agency. We will further focus on delusions of alien control in schizophrenic patients. Experimental data suggest that these patients have an abnormal awareness of effort caused by cerebral anomalies in the frontal and parietal lobes. (shrink)

The text concerns the role of emotions in delusion formation. Provided are definitions from DSM-V and DSM-IV-R and the problems found in those definitions. One of them, the problem of delusion formation, is described when providing cognitive theories of delusions. The core of the paper is a presentation of the emotional and affective disorders in delusions, especially Capgras delusion and Cotard delusion. The author provides a comparison of the kinds of delusions and the conclusions taken from neuroimaging studies. As a (...) result of the fact that an explanation of delusion formation focusing on emotional problems turns out to be insufficient, the author provides examples of the reasoning impairments which coexist with them. At the end of the article, some hypotheses are proposed concerning the role of emotions and reasoning in delusion formation and the relation between belief disorders and emotional disorders. (shrink)

The aim of this article is to analyze those theories that interpret misidentification delusions in terms of mentalization. The hypothesis under examination holds that a mentalization framework is useful for describing misidentification delusions when identification is thought to be partially based on mentalization. The article provides both a characterization and possible interpretations of such delusions, and possible relations between misidentification and mentalization are scrutinized. Whether the mentalization approach may explain or describe such kinds of mental disorders is considered, with the (...) conclusion that while this approach is unsatisfactory, there is some room for future improvement. (shrink)