In order to explain delusional beliefs, one must first consider what factors should be included in a theory of delusion. Unlike a one-factor theory, a two-factor theory of delusion argues that not only anomalous experience (the first factor) but also an impairment of the belief-evaluation system (the second factor) is required. Recently, two-factor theorists have adopted various Bayesian approaches in order to give a more accurate description of delusion formation. By reviewing the progression from a one-factor theory to a two-factor (...) theory, I argue that in light of the second factor’s requirements, different proposed impairments can be unified within a consistent belief-evaluation system. Under this interpretation of the second factor, I further argue that the role of a mechanism responsible for detecting bizarreness is wrongly neglected. I conclude that the second factor is a compound system which consists of differing functional parts, one of which functions to detect bizarreness in different stages of delusion; moreover, I hold that the impairment can be one or several of these functional parts. (shrink)

The sense of embodiment is vital for self recognition. An examination of anosognosia for hemiplegia—the inability to recognise that one is paralysed down one side of one’s body—suggests the existence of ‘online’ and ‘offline’ representations of the body. Online representations of the body are representations of the body as it is currently, are newly constructed moment by moment and are directly “plugged into” current perception of the body. In contrast, offline representations of the body are representations of what the body (...) is usually like, are relatively stable and are constructed from online representations. This distinction is supported by an analysis of phantom limb—the feeling that an amputated limb is still present—phenomena. Initially it seems that the sense of embodiment may arise from either of these types of representation; however, an integrated representation of the body seems to be required. It is suggested information from vision and emotions is involved in generating these representations. A lack of access to online representations of the body does not necessarily lead to a loss in the sense of embodiment. An integrated offline representation of the body could account for the sense of embodiment and perform the functions attributed to this sense. (shrink)

An examination of alien abduction belief can inform how we ought to approach constructing explanations of monothematic delusion formation. I argue that the formation and maintenance of alien abduction beliefs can be explained by a one-factor account, and that this explanatory power generalizes to (other) cases of monothematic delusions. There are no differences between alien abduction beliefs and monothematic delusions which indicate the need for additional explanatory factors in cases of the latter. I make the additional point that whilst alien (...) abduction beliefs can be readily explained using a one-factor framework, the two-factor framework requires adjustment to accommodate them. I conclude that theorists interested in delusion formation have much to learn from the case of alien abduction belief. (shrink)

ABSTRACTEmpiricists about monothematic delusion formation agree that anomalous experience is a factor in the formation of these attitudes, but disagree markedly on which further factors need to be specified. I argue that epistemic innocence may be a unifying feature of monothematic delusions, insofar as a judgment of epistemic innocence to this class of attitudes is one that opposing empiricist accounts can make. The notion of epistemic innocence allows us to tell a richer story when investigating the epistemic status of monothematic (...) delusions, one which resists the trade-off view of pragmatic benefits and epistemic costs. Though monothematic delusions are often characterized by appeal to their epistemic costs, they can play a positive epistemic role, and this is a surprising conclusion on which, so I argue, all empiricists can agree. Thus, I show that all empiricists have the notion of epistemic innocence at their disposal. (shrink)

In his recent book Delusions and Beliefs, Kengo Miyazono offers a thoroughgoing defence of delusions as biologically malfunctioning beliefs, greatly elaborating on his earlier defence of this view. Miyazono has it that delusions have biological doxastic functions, and that delusions involve direct or indirect malfunctions of this kind. In this short piece, I focus on Miyazono’s defence of a two-factor approach to delusion formation as it appears in Chapter Four. Miyazono approaches his discussion of the debate between one- and two-factor (...) theories having already defended the key thesis of the book: that delusions are malfunctioning beliefs. Of course, that thesis might be thought to mesh nicely with the two-factor theorist’s claim that there is a cognitive abnormality present in delusion formation or maintenance. However, I will discuss Miyazono’s defence of the two-factor position in isolation from its role in his overall account of delusion. Miyazono abstracts away from the particulars of Max Coltheart’s two-factor view, and takes himself to be investigating the plausibility of two-factor theories without the specific commitments of Coltheart’s view. Miyazono also captures under the two-factor heading theories which locate the second factor in belief maintenance rather than just in belief formation. He puts forward a new argument for a two-factor approach which goes via inference to the best explanation. I begin by arguing that Miyazono’s starting motivation for a two-factor approach rests on a misrepresentation of the one-factor approach. Then, I turn to the four components of Miyazono’s inference to the best explanation argument, and argue that in each case, we do not have grounds for positing a second factor. (shrink)

Anosognosia for hemiplegia is the denial of neurologically-caused paralysis, and it often co-occurs with a number of distortions of belief and emotion such as somatoparaphrenia and an exaggeration of negative affect towards minor health complaints. The salience of these latter symptoms led early investigators to propose explanations of AHP which construed it as a process of motivated self-deception against the overwhelming anxiety and depression that knowledge of deficit would otherwise cause, and which was observed in hemiplegic patients without the anosognosia. (...) Since some influential critiques of this approach, however, theories of this kind have largely been rejected on the grounds that they are inappropriately “psychogenic.” What has replaced them are a class of theories which explain the lack of awareness in terms of neurocognitive deficit, with the deficit in question variously described by researchers as involving spatial awareness, motor control, and other capacities. In this paper I argue – contra claims in the literature – that the patterns of explanation which are characteristic of the psychodynamic theory are not incompatible in principle with the notion that the illness involves neurocognitive deficit. That means that these patterns of explanation can be preserved where they make good sense of the obscure attitudinal and emotional symptoms that occur in AHP – symptoms that are otherwise difficult to explain. I suggest some ways in which this fact could be accommodated by deficit theories of the illness which are based on motor deficit. (shrink)

Maher proposed in 1974 that schizophrenic delusions are hypotheses formed to explain anomalous experiences. He stated that they are “rational, given the intensity of the experiences that they are developed to explain.” Two-factor theorists of delusion criticized Maher’s theory because 1) it does not explain why some patients with anomalous experiences do not develop delusions, and 2) adopting and adhering to delusional hypotheses is irrational, considering the totality of experiences and patients’ other beliefs. In this paper, the notion of the (...) intensity of experience is reappraised to uphold Maher’s basic conception. Regarding 1), I propose that differences in the intensity of anomalous experience are vital to whether the patient forms delusions, while partially reforming his rationality claim regarding 2). Although adopting delusions is irrational, it is inevitable and excusable, given the intensity of the patient’s anomalous experience. With the aid of this notion, it is maintained that anomalous experience is sufficient for the development of delusions, at least in some cases of schizophrenia. Compared to other theories of schizophrenic delusion, Maher’s theory, which embraces the notion of intensity of experience, better explains why such irrational mental states as delusions develop from anomalous experiences, and why delusional patients persist in believing specific thematic content. (shrink)

In both cognitive science and philosophy, many theorists have recently appealed to a predictive processing framework to offer explanations of why certain individuals form delusional beliefs. One aim of this essay will be to illustrate how one could plausibly develop a predictive processing account in different ways to account for the onset of different kinds of delusions. However, the second aim of this essay will be to discuss two significant limitations of the predictive processing framework. First, I shall draw on (...) the structure of explanatory why-questions to argue that predictive processing theories can only partially explain the formation of delusional beliefs. Second, I shall argue that predictive processing theories cannot explain how implausible delusional hypotheses are generated. Yet understanding why an agent even generates a delusional hypothesis is a crucial step to understanding why she eventually comes to believe it. The final section of the essay presents three alternative ways the process of hypothesis generation might be functionally divergent in cases of delusional cognition. (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)

Monothematic delusions involve a single theme, and often occur in the absence of a more general delusional belief system. They are cognitively atypical insofar as they are said to be held in the absence of evidence, are resistant to correction, and have bizarre contents. Empiricism about delusions has it that anomalous experience is causally implicated in their formation, whilst rationalism has it that delusions result from top down malfunctions from which anomalous experiences can follow. Within empiricism, two approaches to the (...) nature of the abnormality/abnormalities involved have been touted by philosophers and psychologists. One-factor approaches have it that monothematic delusions are a normal response to anomalous experiences whilst two-factor approaches seek to identify a clinically abnormal pattern of reasoning in addition to anomalous experience to explain the resultant delusion. In this paper we defend a one-factor approach. We begin by making clear what we mean by atypical, abnormal, and factor. We then identify the phenomenon of interest and overview one and two-factor empiricism about its formation. We critically evaluate the cases for various second factors, and find them all wanting. In light of this we turn to our one-factor account, identifying two ways in which ‘normal response’ may be understood, and how this bears on the discussion of one-factor theories up until this point. We then conjecture that what is at stake is a certain view about the epistemic responsibility of subjects with delusions, and the role of experience, in the context of familiar psychodynamic features. After responding to two objections, we conclude that the onus is on two-factor theorists to show that the one-factor account is inadequate. Until then, the one-factor account ought to be understood as the default position for explaining monothematic delusion formation and retention. We don’t rule out the possibility that, for particular subjects with delusions there may be a second factor at work causally implicated in their delusory beliefs but, until the case for the inadequacy of the single factor is made, the second factor is redundant and fails to pick out the minimum necessary for a monothematic delusion to be present. (shrink)

Reflection on skeptical scenarios in the philosophy of perception, made vivid in the arguments from illusion and hallucination, have led to the formulation of theories of the metaphysical and epistemological nature of perceptual experience. In recent times, the locus of the debate concerning the nature of perceptual experience has been the dispute between disjunctivists and common-kind theorists. Disjunctivists have held that there are substantial dissimilarities (either metaphysical or epistemological or both) between veridical perceptual experiences occurring when one perceives and perceptual (...) experiences involved in hallucination. Common-kind theorists have denied this. In this paper, I examine the nature of introspection – a faculty that has often been compared and contrasted to perception. I reflect on cases where introspection goes wrong in ways analogous to that in which our perceptual faculties can go wrong and formulate, what I take to be, an attractive theory of introspection. The cases that I focus on in which things go wrong are the case of zombies and the case of subjects with Anton’s syndrome. (Anton’s syndrome is a condition in which people who are blind claim that they can see.) I suggest that, just as it is possible to be a disjunctivist about perception, it is possible to be a disjunctivist about introspection. I argue that this is a good view of one type of introspection, namely, introspection of states that have phenomenal character, such as perceptual experiences. It has a good account to give of the cases in which such introspection seems to go wrong and it yields a plausible metaphysical and epistemological view of the nature of introspection. However, while I favour a disjunctive view of introspection, I do not favour a disjunctive view of perception. And, I suspect, that many disjunctivists about perception would not wish to condone my disjunctivist theory of introspection. I therefore go on to examine to what extent.. (shrink)

The neuropathologies of the self are disorders of the self and identity that occur in association with neuropathology and include perturbations of the bodily, relational, and narrative self. Right, especially medial-frontal and orbitofrontal lesions, are associated with these conditions. The ego disequilibrium theory proposes this brain pathology causes a disturbance of ego boundaries and functions and the emergence of developmentally immature styles of thought, ego functioning, and psychological defenses including denial, projection, splitting, and fantasy that the NPS patient has in (...) common with the child. I hypothesize that during brain development between approximately ages 3 and 7 immature defensive functions and fantasies tend to be replaced by mature defenses and the inhibition of fantasy a process that depends upon maturational processes within the right hemisphere. I propose a four-tiered model of the NPS that emphasizes a multifactorial approach and includes both negative and positive, bottom up and top down, and neuropsychological and psychological factors. (shrink)

A growing number of studies in both the scientific and the philosophical literature have drawn on a Bayesian predictive processing framework to account for the formation of delusions. The key here is that delusions form because of disrupted prediction error signalling. Parrott’s recent critique argues that the framework is incomplete in two respects: it leaves unclear why delusional hypotheses are selected over none at all or over more plausible alternatives; it leaves unclear how exactly it is that delusional hypotheses are (...) generated in the first place. In this paper, we defend the framework’s explanatory power by way of showing how it can go a long way in helping disentangle these concerns. We take up each of them in turn. As for the first, our argument turns on two claims: a) believing nothing, although possible in principle, may not be a viable procedure in the circumstances; b) alternative hypotheses may be rendered unavailable for selection, due to aberrant prediction errors. As for the second concern, we distinguish three ways in which delusional hypotheses may be initially acquired, all of which are based on experience broadly construed. (shrink)

This paper reviews the literature concerning the neural correlates of the self, the relationship between self and memory and the profile of memory impairments in Alzheimer’s disease and explores the relationship between the preservation of the self and anosognosia in this condition. It concludes that a potential explanation for anosognosia in AD is a lack of updating of personal information due to the memory impairments characteristic of this disease. We put forward the hypothesis that anosognosia is due in part to (...) the “petrified self.”. (shrink)

Introspection has traditionally been defined as a privileged way of obtaining beliefs about one’s occurrent mental states, and the idea that it is psychologically and epistemically different from non-introspective belief formation processes has been widely defended. At the same time, philosophers and cognitive scientists alike have pointed out the unreliability of introspective reports in consciousness research. In this paper, I will argue that this dissonance in the literature can be explained by differentiating between infallible and informative introspective beliefs. I will (...) argue that the latter are formed similarly to beliefs about the external world, and are therefore susceptible to similar success and failure conditions. Understanding introspection as belief-like will help to locate possible sources of error in regular as well as in pathological cases, carrying relevant implications for the relationship between experience, belief, and delusion. (shrink)

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)

Hysteria has been the subject of controversy for many years, with theorists arguing about whether it is best explained by a hidden organic cause or by malingering and deception. However, it has been shown that hysterical paralysis cannot be explained in any of these terms. With the recent development of cognitive psychiatry, one may understand psychiatric and organic delusions within the same conceptual framework. Here I contrast hysterical conversion with anosognosia. They are indeed remarkably similar, though the content of their (...) respective delusions is the opposite. In hysterical paralysis, patients are not aware of their preserved ability, whereas in anosognosia for hemiplegia, patients are not aware of their disability. Four main explanations have been provided to account for anosognosia: metacognitive, attentional, motor, and motivational views. I will apply each of these accounts to hysterical paralysis and show that, at each level, hysterical conversion is the reverse of anosognosia. I will suggest that hysterical paralysis results from the interaction between attentional somatosensory amplification and affective inhibition of action. (shrink)