The patient with Capgras’ syndrome claims that people very familiar to him have been replaced by impostors. I argue that this disorder is due to the destruction of a representation that the patient has of the mind of the familiar person. This creates the appearance of a familiar body and face, but without the familiar personality, beliefs, and thoughts. The posterior site of damage in Capgras’ is often reported to be the temporoparietal junction, an area that has a (...) role in the mindreading system, a connected system of cortical areas that allow us to attribute mental states to others. Just as the Capgras’ patient claims that that man is not his father, the patient with asomatognosia claims that his arm is not really his. A similar account applies here, in that a nearby brain area, the supramarginal gyrus, is damaged. This area works in concert with the temporoparietal junction and other areas to produce a large representation of a mind inside a body situated in an environment. Damage to the mind-representing part of this system (coupled with damage to executive processes in the prefrontal lobes) causes Capgras’ syndrome, whereas damage to the body-representing part of this system (also coupled with executive damage) causes asomatognosia. (shrink)

My central question in this paper is how delusional beliefs are related to self-deception. In section 1, I summarize my position on what self-deception is and how representative instances of it are to be explained. I turn to delusions in section 2, where I focus on the Capgras delusion, delusional jealousy (or the Othello syndrome), and the reverse Othello syndrome.

The Capgras delusion is a condition in which a person believes that an imposter has replaced some close friend or relative. Recent theorists have appealed to Bayesianism to help explain both why a subject with the Capgras delusion adopts this delusional belief and why it persists despite counter-evidence. The Bayesian approach is useful for addressing these questions; however, the main proposal of this essay is that Capgras subjects also have a delusional conception of epistemic possibility, more specifically, (...) they think more things are possible, given what is known, than non-delusional subjects do. I argue that this is a central way in which their thinking departs from ordinary cognition and that it cannot be characterized in Bayesian terms. Thus, in order to fully understand the cognitive processing involved in the Capgras delusion, we must move beyond Bayesianism. 1 The Simple Bayesian Model2 Anomalous Evidence and the Capgras Delusion3 Impaired Reasoning4 Setting Priors5 Epistemic Modality6 Delusions of Possibility7 Delusions of Possibility in Different Contexts8 How Many Factors? (shrink)

People suffering from severe monothematic delusions, such as Capgras, Fregoli, or Cotard patients, regularly assert extraordinary and unlikely things. For example, some say that their loved ones have been replaced by impostors. A popular view in philosophy and cognitive science is that such monothematic delusions aren't beliefs because they don't guide behaviour and affect in the way that beliefs do. Or, if they are beliefs, they are somehow anomalous, atypical, or marginal beliefs. We present evidence from five studies that (...) folk psychology unambiguously views monothematic delusions as stereotypical beliefs. This calls into question widespread assumptions in the professional literature about belief's stereotypical functional profile. We also show that folk psychology views delusional patients as holding contradictory beliefs. And we show that frequent assertion is a powerful cue to belief ascription, more powerful than even a robust and consistent track record of non-verbal behaviour. (shrink)

This paper examines Todd Feinberg's theory of the misidentification syndromes.

Delusional beliefs have sometimes been considered as rational inferences from abnormal experiences. We explore this idea in more detail, making the following points. Firstly, the abnormalities of cognition which initially prompt the entertaining of a delusional belief are not always conscious and since we prefer to restrict the term “experience” to consciousness we refer to “abnormal data” rather than “abnormal experience”. Secondly, we argue that in relation to many delusions (we consider eight) one can clearly identify what the abnormal cognitive (...) data are which prompted the delusion and what the neuropsychological impairment is which is responsible for the occurrence of these data; but one can equally clearly point to cases where this impairments is present but delusion is not. So the impairment is not sufficient for delusion to occur. A second cognitive impairment, one which impairs the ability to evaluate beliefs, must also be present. Thirdly (and this is the main thrust of our chapter) we consider in detail what the nature of the inference is that leads from the abnormal data to the belief. This is not deductive inference and it is not inference by enumerative induction; it is abductive inference. We offer a Bayesian account of abductive inference and apply it to the explanation of delusional belief. (shrink)

In this paper, I am generally concerned with certain mental disorders and the doxastic attitudes that sometimes characterize them. According to recent Anglo-American philosophical studies on this topic, the latter involve beliefs that have somehow “gone wrong”: strange or irrational beliefs and cases of “motivated irrationality”. I aim to focus on pathological and deceptive phenomena such as delusion and self-deception. From a phenomenological perspective, these can also be investigated with regard to their experiential content. Adopting this approach, and starting in (...) particular with the eidetic connection between the living body and its own environment, I will examine disorders of the ecological self. Psychiatric delusion, which is at the core of this examination, is a symptom of a great number of mental disorders, such as Capgras disorder, Cotard disorder and schizophrenia. Integrating dominant (propositional) models of delusion which reduce this pathological phenomenon to a certain kind of belief, I propose an eco-phenomenological understanding of its contours. From this perspective, delusion reveals itself primarily as an illusory experience: a delusional value-perception. In particular, I offer a Schelerian-based description of a peculiar case of delusion: Capgras delusion. People who suffer from Capgras delusion claim that an otherwise familiar individual has been replaced by an impostor. I consider, although in its negative variations, the contextual (rather than internalist) character of this type of delusion. (shrink)

The cognitive science of belief is a burgeoning field, with insights ranging from detailing the fundamental structure of the mind, to explaining the spread of fake news. Here we highlight how new insights into belief acquisition, storage, and change can transform our understanding of psychiatric disorders. Although we focus on monothematic delusions, the conclusions apply more broadly. -/- .