Ordinary people tend to be realists regarding perceptual experience, that is, they take perceiving the environment as a direct, unmediated, straightforward access to a mindindependent reality. Not so for (ordinary) philosophers. The empiricist influence on the philosophy of perception, in analytic philosophy at least, made the problem of perception synonymous with the view that realism is untenable. Admitting the problem (and trying to offer a view on it) is tantamount to rejecting ordinary people’s implicit realist assumptions as naive. So what (...) exactly is the problem? We can approach it via one of the central arguments against realism – the argument from hallucination. The argument is intended as a proof that in ordinary, veridical cases of perception, perceivers do not have an unmediated perceptual access to the world. There are many versions of it; I propose the following1: 1. Hallucinations that are subjectively indistinguishable from veridical perceptions are possible. 2. If two subjective states are indistinguishable, then they have a common nature. 3. The contents of hallucinations are mental images, not concrete external objects. 4. Therefore, the contents of veridical perceptions are mental images rather than concrete external objects. The key move is, I believe, from the fact that hallucinations that are subjectively indistinguishable from cases of veridical perception are possible to an alleged common element, factor, or nature, in the form of a mental state, in the two cases – that is, premise 2. Disjunctivism, at its core, can be taken as simply denying this move, and arguing that all that follows from the premise stating the possibility of hallucinations that are subjectively indistinguishable from cases veridical perception is that there is a broader category, that of “experience as of...”, which encompasses both cases.. (shrink)
Like dreaming, hallucination has been a formative trope for modern philosophy. The vivid, often tragic, breakdown in the mind’s apparent capacity to disclose reality has long served to support a paradoxical philosophical picture of sensory experience. This picture, which of late has shaped the paradigmatic empirical understanding the senses, displays sensory acts as already complete without the external world; complete in that the direct objects even of veridical sensory acts do not transcend what we could anyway hallucinate. Hallucination (...) is thus the mother of Representationalism, which insists that it is mental intermediaries that make other.. (shrink)
Although it has been something of a fetish for philosophers to distinguish between hallucination and illusion, the enduring problems for philosophy of perception that both phenomena present are not essentially different. Hallucination, in its pure philosophical form, is just another example of the philosopher’s penchant for considering extreme and extremely idealized cases in order to understand the ordinary. The problem that has driven much philosophical thinking about perception is the problem of how to reconcile our evident direct perceptual (...) contact with objects and properties with the equally evident fact that there is no phenomenological signal separating error and truth. “The obscure object of hallucination” offers a subtle and plausible solution to this problem and one that solves the problem generally, not just in the special case of hallucination. Johnston’s objective is to offer a theory of perception that meets two constraints: (1) that it provide an explanation of the possibility of delusive and veridical sensings that are indistinguishable from the first-person perspective and (2) that it count as form of direct realism where this is taken to involve acquaintance with the objects of perception. Johnston uses the first constraint to rule out disjunctivism. The second constraint is used to rule out conjunctivism, which as Johnston uses the term, includes most of the widely adopted philosophical theories of perception. Johnston also develops his own sophisticated and interesting theory of perception. In what follows, I will discuss the relation of Johnston’s theory to conjunctivism, examine one of his anti-conjunctivist arguments and finally compare Johnston’s theory with some other versions of direct realism. These topics constitute a very incomplete selection of the important issues discussed in this rich and interesting paper. I will also not disagree, in any fundamental way, with any of the central theses of Johnston’s discussion.. (shrink)
Do self-monitoring accounts, a dominant account of the positive symptoms, explain auditory verbal hallucination (AVH)? In this essay, I argue that the account fails to answer many crucial questions any explanation of AVH must address. Where the account provides a plausible answer, I make a case for an alternative explanation: AVH is not the result of a failed control mechanism, namely failed self-monitoring, but the persistent automaticity of auditory experience of a voice. The argument emphasizes the importance of careful (...) examination of phenomenology as a constraint on causal models of the positive symptoms in schizophrenia. (shrink)
Perceptual experiences have been construed either as representational mental states—Representationalism—or as direct mental relations to the external world—Disjunctivism. Both conceptions are critical reactions to the so-called ‘Argument from Hallucination’, according to which perceptions cannot be about the external world, since they are subjectively indiscriminable from other, hallucinatory experiences, which are about sense-data ormind-dependent entities. Representationalism agrees that perceptions and hallucinations share their most specific mental kind, but accounts for hallucinations as misrepresentations of the external world. According to Disjunctivism, the (...) phenomenal character of perceptions is exhausted by worldly objects and features, and thus must be different from the phenomenal character of hallucinations. Disjunctivism claims that subjective indiscriminability is not the result of a common experiential ground, but is because of our inability to discriminate, from the inside, hallucinations from perceptions. At first sight, Representationalism is more congenial to the way cognitive science deals with perception. However, empirically oriented revisions of Disjunctivism could be developed and tested by giving a metacognitive account of hallucinations. Two versions of this account can be formulated, depending on whether metacognition is understood as explicit metarepresentation or as implicit monitoring of first-order informational states. The first version faces serious objections, but the second is more promising, as it embodies a more realistic view of perceptual phenomenology as having both sensory and affective aspects. Affectbased phenomenology is constituted by various metacognitive feelings, such as the feeling of being perceptually confronted with the world itself, rather than with pictures or mere representations. (shrink)
Direct realists think that we can't get a clear view the nature of /hallucinating a white picket fence/: is it /representing a white picket fence/? is it /sensing white-picket-fencily/? is it /being acquainted with a white' picketed' sense-datum/? These are all epistemic possibilities for a single experience; hence they are all metaphysical possibilities for various experiences. Hallucination itself is a disjunctive or "multidisjunctive" category. I rebut MGF Martin's argument from statistical explanation for his "epistemic" conception of hallucination, but (...) his view embeds in my view as a "reference-fixer". (shrink)
Tradition has it that, although we experience darkness, we can neither hear nor hallucinate silence. At most, we hear that it is silent, in virtue of lacking auditory experience. This cognitive view is at odds with our ordinary thought and talk. Yet it is not easy to vouchsafe the perception of silence: Sorensen‘s recent account entails the implausible claim that the permanently and profoundly deaf are perpetually hallucinating silence. To better defend the view that we can genuinely hear and hallucinate (...) silence, we must reject the austere picture of conscious experience which underpins the cognitive theory. According to that picture, conscious experience is a simple relation between subjects and objects. In the absence of an object, there is no relation, and so no experience. By enriching this picture, room can be found for the experience of silence. I explore this idea in two phases. First, I defend the thought that we can hear and hallucinate certain forms of silence, such as pauses, in virtue of experiencing contrastive sounds. Second, I draw on Moore‘s analysis of sensation to suggest that simply experiencing silence is a special form of objectless consciousness. I offer two ways of fleshing out this idea. According to the first, auditory experience possesses a temporal field within which the absence of sounds can be perceived. According to the second, purely Moorean account, it is our capacity to listen in the absence of sounds that underlies the phenomenon of experiencing silence. (shrink)
Early formulations of disjunctivism about perception refused to give any positive account of the nature of hallucination, beyond the uncontroversial fact that they can in some sense seem to the same to the subject as veridical perceptions. Recently, some disjunctivists have attempt to account for hallucination in purely epistemic terms, by developing detailed account of what it is for a hallucinaton to be indiscriminable from a veridical perception. In this paper I argue that the prospects for purely epistemic (...) treatments of hallucinations are dim, and that this undermines the case for disjunctivism. (shrink)
In the eyes of some of its critics, disjunctivism fails to support adequately the key claim that a particular hallucination might be indistinguishable from a certain kind of veridical perception despite the two states having nothing other than this in common. Scott Sturgeon, for example, has complained that disjunctivism ‘‘offers no positive story about hallucination at all’’ (2000: 11) and therefore ‘‘simply takes [indistinguishability] for granted’’ (2000: 12). So according to Sturgeon, what the disjunctivist needs to provide is (...) a plausible explanation of just how two mental states which have no common component might be indistinguishable for their subject and this in turn will require the telling of a positive story about hallucination. This is the goal of the present essay. (shrink)
Phenomenal character is determined by representational content, which both hallucinatory and veridical experiences can share. But in the case of veridical experience, unlike hallucination, the external objects of experience literally have the properties one is aware of in experience. The representationalist can accept the common factor assumption without having to introduce sensory intermediaries between the mind and the world, thus securing a form of direct realism.
According to the epistemic theory of hallucination, the fundamental psychological nature of a hallucinatory experience is constituted by its being ‘introspectively indiscriminable’, in some sense, from a veridical experience of a corresponding type. How is the notion of introspective indiscriminability to which the epistemic theory appeals best construed? Following M. G. F. Martin, the standard assumption is that the notion should be construed in terms of negative epistemics: in particular, it is assumed that the notion should be explained in (...) terms of the impossibility that a hallucinator might possess a certain type of knowledge on a certain basis. I argue that the standard assumption is mistaken. I argue that the relevant notion of introspective indiscriminability is better construed in terms of positive epistemics: in particular, I argue that the notion is better explained by reference to the fact that it would be rational for a hallucinator positively to make a certain type of judgement, were that judgement made on a certain basis. (shrink)
The paper proposes a minimal definition of dreaming in terms of immersive spatiotemporal hallucination (ISTH) occurring in sleep or during sleep–wake transitions and under the assumption of reportability. I take these conditions to be both necessary and sufficient for dreaming to arise. While empirical research results may, in the future, allow for an extension of the concept of dreaming beyond sleep and possibly even independently of reportability, ISTH is part of any possible extension of this definition and thus is (...) a constitutive condition of dreaming. I also argue that the proposed ISTH model of dreaming, in conjunction with considerations on the epistemic relationship between dreaming and dream reports, raises important questions about the extent to which dreams typically involve a detailed body representation—an assumption that plays an important role in philosophical work on dreaming. As a commonly accepted definition of dreaming is lacking in current dream research, the ISTH model, which integrates conceptual analysis and epistemological considerations with results from empirical research, is an important contribution to this field. By linking dreaming to felt presence, full-body illusions, and autoscopic phenomena such as out-of-body experiences in wakefulness and in the hypnagogic state, the ISTH model of dreaming also helps integrate dream research, both theoretically and experimentally, with the study of other altered states of consciousness involving hallucinations. It makes straightforward and investigable predictions by claiming that all of these experiences have amodal spatiotemporal hallucinations as their common denominator. Finally, it is theoretically relevant for the philosophical discussion on minimal phenomenal selfhood. (shrink)
Patrick Suppes'' set-theoretical approach to the analysis of theories, and Joseph D. Sneed''s metatheory are briefly outlined. The notions of observation, illusion and hallucination are reconstructed according to these approaches. It is argued that the terms perception and truth are theoretical with respect to observation but nontheoretical with respect to illusion and hallucination. Hallucination is construed as a special kind of illusion.
If perception is constructed, what keeps perception from becoming mere hallucination unlinked to world events? The visual system has evolved two strategies to anchor itself and correct its errors. One involves completing missing information on the basis of knowledge about what most likely exists in the scene. For example, the visual system fills in information only in cases where it might be responsible for the data loss. The other strategy involves exploiting the physical stability of the environment as a (...) reference frame with respect to which the eyes and body can move. (shrink)
We argue that the pivotal role assigned by Northoff to the principle of top-down modulation in catatonia might successfully be applied to other symptoms of schizophrenia, for example, hallucinations. Second, we propose that Northoff's account would benefit from a more comprehensive analysis of the cognitive level of explanation. Finally, contrary to Northoff, we hypothesize that “top-down modulation” might play as important a role as “horizontal modulation” in affective-behavioral alterations.
In his article “Constructive Empiricism Now” van Fraassen chooses an extremely interesting example to defend his thesis that scientific theories are only representations, so that the aim of science is to give us reliable, empirically adequate, descriptions of the observable aspects of the world. For him, there is no continuum of observable/unobservable, as he draws a line of distinction at a point that eliminates from his ontology such cases as fields of forces and sub-atomic particles. As a result, he puts (...) forward the position that electronic images in the microscope and subatomic particles are “public hallucinations” and not “real things”. What I thus propose to do is to examine van Fraassen’s anti-realism through the looking class of realism, my aim being to defend a realist view of science: To this purpose, I will focus on two main issues: (a) the question of representations in science and in particular of images we “see” through a microscope and (b) the question of the criteria for defining physical reality. In this context, I will argue that van Fraassen’s definition of the “real” is an anti-realist version of the positivist trend, which cannot fit in the picture of science that emerges today. To understand, thus, the world of physics we need to re-examine our definition of reality and make space for an ontology that goes beyond the well-defined spatio-temporal existence of what van Fraassen calls a “real thing”. (shrink)
Disjunctivism about perceptual appearances, as I conceive of it, is a theory which seeks to preserve a naïve realist conception of veridical perception in the light of the challenge from the argument from hallucination. The naïve realist claims that some sensory experiences are relations to mind-independent objects. That is to say, taking experiences to be episodes or events, the naïve realist supposes that some such episodes have as constituents mind-independent objects. In turn, the disjunctivist claims that in a case (...) of veridical perception like this very kind of experience that you now have, the experiential episode you enjoy is of a kind which could not be occurring were you having an hallucination. The common strategy of arguments from hallucination set out to show that certain things are true of hallucinations, and hence must be true of perceptions. For example, it is argued that hallucinations must have non-physical objects of awareness, or that such states are not relations to anything at all, but are at best seeming relations to objects. In insisting that veridical perceptual experience is of a distinct kind from hallucination, the disjunctivist denies that any of these conceptions of hallucination challenges our conception of veridical perceptions as relations to mind-independent objects. More specifically, I assume that the disjunctivist advocates naïve realism because they think that this position best articulates how sensory experience seems to us to be just through reflection. If the disjunctivist is correct in this contention, then anyone who accepts the conclusion of the argument from hallucination must also accept that the nature of sensory experience is other than it seems to us to be. In turn, one may complain that any such error theory is liable to lead to sceptical consequences. A Humean scepticism about the senses launches a challenge about our knowledge of the world through questioning the conception we have of what sense experience is, and how it can provide knowledge of the world.. (shrink)
Of all the problems attending the sense-datum theory, arguably the deepest is that it draws a veil of appearances over the external world. Today, the sense-datum theory is widely regarded as an overreaction to the problem of hallucination. Instead of accounting for hallucination in terms of intentional relations to sense data, it is often thought that we should account for it in terms of intentional relations to properties. In this paper, however, I argue that in the versions that (...) might address the problem of hallucination, this newer account is guilty of a vice similar to sense-datum theory’s: it draws a veil of abtracta over the concrete world. (shrink)
We can learn much about perceptual experience by thinking about how it can mislead us. In this paper, I explore whether, and how, olfactory experience can mislead. I argue that, in the case of olfactory experience, the traditional distinction between illusion and hallucination does not apply. Integral to the traditional distinction is a notion of ‘object-failure’—the failure of an experience to present objects accurately. I argue that there are no such presented objects in olfactory experience. As a result, olfactory (...) experience can only mislead by means of a kind of property hallucination. The implications of my arguments are twofold. First, we see that accounts of representational content cannot always be based on the visual model. And, secondly, we see that we must recast the notion of nonveridicality, allowing for a notion of non-veridical experience that is disengaged from any particular object. (shrink)
Abstract: How exactly should the relation between a veridical perception and a corresponding hallucination be understood? I argue that the epistemic notion of ‘indiscriminability’, understood as lacking evidence for the distinctness of things, is not suitable for defining this relation. Instead, we should say that a hallucination and a veridical perception involve the same phenomenal properties. This has further consequences for attempts to give necessary and sufficient conditions for the identity of phenomenal properties in terms of indiscriminability, and (...) for considerations about the phenomenal sorites. (shrink)
The subjective character of a given experience leaves open the question of its precise status. If it looks to a subject K as if there is an object of a kind F in front of him, the experience he is having could be veridical, or hallucinatory. Advocates of the Causal Theory of perception (whom I shall call.
In the first monograph in this exciting area since then, William Fish develops a comprehensive disjunctive theory, incorporating detailed accounts of the three ...
Nicholas Nathan tries to resist the current version of the causal argument for sense-data in two ways. First he suggests that, on what he considers to be the correct reconstruction of the argument, it equivocates on the sense of proximate cause. Second, he defends a form of disjunctivism, by claiming that there might be an extra mechanism involved in producing veridical hallucination that is not present in perception. I argue that Nathan’s reconstruction of the argument is not the appropriate (...) one, and that, properly interpreted, the argument does not equivocate on proximate cause. Furthermore, I claim that his postulation of a modified mechanism for hallucinations is implausibly ad hoc. (shrink)
In this paper we consider, and reject, Harold Langsams defenceof the Theory of Appearing, in this journal (1997), in the faceof three standard arguments against it. These arguments are:the argument from hallucination; the argument from the samecause-same effect principle; and the argument from perceptualtime-gap.
Many professional organizations have established codes of ethics which members are expected to adhere to. These ethical codes serve an important function by containing the rules that govern the conduct of the members of the profession. Should the tourism industry be governed by a code of ethics? Is it important enough and large enough to spend a lot of time and energy developing a code of ethics since tourism is based on service rather than a physical good, which does not (...) lend itself to standardization or control? This paper will examine these issues. (shrink)
Several authors have recently argued that the content of pains (and bodily sensations more generally) is imperative rather than descriptive. I show that such an account can help resolve competing intuitions about phantom limb pain. As imperatives, phantom pains are neither true nor false. However, phantom limb pains presuppose falsehoods, in the same way that any imperative which demands something impossible presupposes a falsehood. Phantom pains, like many chronic pains, are thus commands that cannot be satisfied. I conclude by showing (...) that some of the negative psychological consequences of chronic pain are a direct consequence of their imperative nature. (shrink)
Many naive realists endorse negative disjunctivist strategy in order to deal with the challenge presented by the possibility of phenomenologically indistinguishable halucination. In the first part of this paper I argue that this approach is methodologically inconsistent because it undercuts the phenomenological motivation that underlies the the appeal of naive realism. In the second part of the paper I develop an alternative to the negative disjunctivist account along broadly Meinongian lines. In the last section of this paper I consider and (...) evaluate a somewhat similar but rival viewof hallucination developed by Mark Johnston. (shrink)
A perceptual experience of a given object seems to make the object itself present to the perceiver’s mind. Many philosophers have claimed that naïve realism (the view that to perceive is to stand in a primitive relation of acquaintance to the world) provides a better account of this phenomenological directness of perceptual experience than does the content view (the view that to perceive is to represent the world to be a certain way). But the naïve realist account of this phenomenology (...) has a conspicuous shortcoming: it explains the phenomenological directness of veridical perceptual experiences but not of hallucinations. Conversely, I maintain that a particular variety of the content view provides a unified account of the phenomenological directness of both veridical and hallucinatory experiences. If so, then contrary to what is often assumed, the phenomenological facts concerning perceptual experience are explained better by the content view than by naïve realism, and consequently, we have a compelling reason to prefer the content view to naïve realism. (shrink)
Synesthetes are people who report having perceptual experiences that are very unusual, such as ?seeing? sounds as colors or ?smelling? colors as odors. It is commonly assumed these days that such synesthetic experiences must be instances of misperceptions. Against this widespread assumption, I will highlight that there is reason to think that at least some synesthetic experiences can be viewed as truly veridical perceptions, and not as illusions or hallucinations. On this view, which I will back up by conceptual arguments (...) and empirical data, synesthesia does sometimes enable the individual to truly pick up on worldly features. In failing to take this possibility on board, the participants in this debate have thus unduly restricted the scope of dialectical options. Finally, the reassessment of synesthetic experiences that I defend in this paper will turn out to have important ramifications not just for synesthesia research, but also for perception theories more generally. (shrink)
Defending a form of naïve realism about visual experiences is quite popular these days. Those naïve realists who I will be concerned with in this paper make a central claim about the subjective aspects of perceptual experiences. They argue that how it is with the perceiver subjectively when she sees worldly objects is literally determined by those objects. This way of thinking leads them to endorse a form of disjunctivism, according to which the fundamental psychological nature of seeings and hallucinations (...) is distinct. I will oppose their central claim by defending a version of the so-called ‘causal argument’, which dwells on ideas about causation and explanation in perception. The aim of this discussion is to highlight that the subjective aspects of perceptual experiences cannot be explained in naïve realist terms. Instead, it will be argued that one needs to appeal to a mental factor which does not involve worldly objects as constituents, and which is common to seeings and hallucinations. (shrink)
The NMDA receptor (NMDAR) channel has been proposed to function as a coincidence-detection mechanism for afferent and reentrant signals, supporting conscious perception, learning, and memory formation. In this paper we discuss the genesis of distorted perceptual states induced by subanesthetic doses of ketamine, a well-known NMDA antagonist. NMDAR blockage has been suggested to perturb perceptual processing in sensory cortex, and also to decrease GABAergic inhibition in limbic areas (leading to an increase in dopamine excitability). We propose that perceptual distortions and (...) hallucinations induced by ketamine blocking of NMDARs are generated by alternative signaling pathways, which include increase of excitability in frontal areas, and glutamate binding to AMPA in sensory cortex prompting Ca ++ entry through voltage-dependent calcium channels (VDCCs). This mechanism supports the thesis that glutamate binding to AMPA and NMDARs at sensory cortex mediates most normal perception, while binding to AMPA and activating VDCCs mediates some types of altered perceptual states. We suggest that Ca ++ metabolic activity in neurons at associative and sensory cortices is an important factor in the generation of both kinds of perceptual consciousness. (shrink)
The NMDA receptor (NMDAR) channel has been proposed to function as a coincidence-detection mechanism for afferent and reentrant signals, supporting conscious perception, learning, and memory formation. In this paper we discuss the genesis of distorted perceptual states induced by subanesthetic doses of ketamine, a well-known NMDA antagonist. NMDAR blockage has been suggested to perturb perceptual processing in sensory cortex, and also to decrease GABAergic inhibition in limbic areas (leading to an increase in dopamine excitability). We propose that perceptual distortions and (...) hallucinations induced by ketamine blocking of NMDARs are generated by alternative signaling pathways, which include increase of excitability in frontal areas, and glutamate binding to AMPA in sensory cortex prompting Ca++ entry through voltage-dependent calcium channels (VDCCs). This mechanism supports the thesis that glutamate binding to AMPA and NMDARs at sensory cortex mediates most normal perception, while binding to AMPA and activating VDCCs mediates some types of altered perceptual states. We suggest that Ca++ metabolic activity in neurons at associative and sensory cortices is an important factor in the generation of both kinds of perceptual consciousness. (shrink)
Michael Martin aims to affirm a certain pattern of first-person thinking by advocating disjunctivism, a theory of perceptual experience which combines naive realism with the epistemic conception of hallucination. In this paper I argue that we can affirm the pattern of thinking in question without the epistemic conception of hallucination. The first part of my paper explains the link that Martin draws between the first-person thinking and the epistemic conception of hallucination. The second part of my paper (...) explains how we can achieve Martin’s ambition without Martin’s theory. One resource that I enlist for this purpose is a naive-realist friendly conception of first-person access to experience. The metaphysical theory that I enlist is a form of naive realism that endorses an intentionalist or representationalist “common-factor” approach to veridical and hallucinatory experience. The third part of my paper briefly develops this theory. (shrink)
A comprehensive theory of the structure and cognitive function of the human imagination, and its relationship to perceptual experience, is developed, largely through a critique of the account propounded in Colin McGinn's Mindsight. McGinn eschews the highly deflationary (and unilluminating) views of imagination common amongst analytical philosophers, but fails to develop his own account satisfactorily because (owing to a scientifically outmoded understanding of visual perception) he draws an excessively sharp, qualitative distinction between imagination and perception (following Wittgenstein, Sartre, and others), (...) and because of his fatally flawed, empirically ungrounded conception of hallucination. In fact, however, an understanding of perception informed by modern visual science will enable us to unify our accounts of perception, mental imagery, dreaming, hallucination, creativity, and other aspects of imagination within a single coherent theoretical framework. (shrink)
It will be obvious to anyone with a slight knowledge of twentieth-century analytic philosophy that one of the central themes of this kind of philosophy is the nature of perception: the awareness of the world through the five senses of sight, touch, smell, taste, and hearing. Yet it can seem puzzling, from our twenty-first-century perspective, why there is a distinctively philosophical problem of perception at all. For when philosophers ask ‘what is the nature of perception?’, the question can be confused (...) with other, purely empirical, questions. For example: how do our sense-organs actually work? What are the mechanisms of smell and taste? How do vision and touch actually provide us with information about the world around us? There is much general agreement, in its broad outlines, about how to answer such questions empirically; but it is not clear what role, if any, philosophy has to play in answering these empirical questions. So if these were the only questions about the nature of perception, then it would not be clear exactly what the philosophy of perception is supposed to be about. Some philosophers (e.g. Brewer 2000) have argued that there is a distinctively philosophical question here, but it is epistemological, viz. how does perception provide 1 reason for our beliefs about the empirical world? This, it seems, is a question which remains to be answered even after the empirical world is done. This is because the question about reasons is normative rather than scientific or descriptive. Even once the psychological theory of vision, for example, has done its job in describing fully the mechanisms of vision, the normative question still can be asked: what makes this process result in something which gives a reason, something which justifies a belief? Suppose I see a bottle before me, and come to believe on the basis of this that there is a bottle before me. My reason for believing that this is a bottle is that I can see it. But what makes seeing the bottle a reason for this belief? It can be argued that the need to give a satisfactory answer to this question constrains our choice of theory of perception.. (shrink)
In this paper, I examine the so-called disjunctive views on hallucinations. I argue that neither of the options open to the disjunctivist is capable of accommodating basic phenomenological facts about hallucinatory experiences and the explanatory demands behind the classical argument from hallucination. A positive characterization of the hallucinatory case is not attractive to a disjunctivist once she is disposed to accept certain commonalities with veridical experiences. Negative disjunctivism glosses the hallucinatory disjunct in terms of indiscriminability. I will argue that (...) this move either renounces to characterize phenomenally the hallucinatory experience or does not take seriously questions about why indiscriminability is possible in the phenomenal realm. (shrink)
In the present paper, I shall argue that disjunctively construed naïve realism about the nature of perceptual experiences succumbs to the empirically inspired causal argument. The causal argument highlights as a first step that local action necessitates the presence of a type-identical common kind of mental state shared by all perceptual experiences. In a second step, it sets out that the property of being a veridical perception cannot be a mental property. It results that the mental nature of perceptions must (...) be exhausted by the occurrence of inner sensory experiences that narrowly supervene on the perceiver. That is, empirical objects fail directly to determine the perceptual consciousness of the perceiver. The upshot is that not only naïve realism, but also certain further forms of direct realism have to be abandoned. (shrink)
Auditory verbal hallucinations (AVHs) are a highly complex and rich phenomena, and this has a number of important clinical, theoretical and methodological implications. However, until recently, this fact has not always been incorporated into the experimental designs and theoretical paradigms used by researchers within the cognitive sciences. In this paper, we will briefly outline two recent examples of phenomenologically informed approaches to the study of AVHs taken from a cognitive science perspective. In the first example, based on Larøi and Woodward (...) (Harv Rev Psychiatry 15:109–117, 2007 ), it is argued that reality monitoring studies examining the cognitive underpinnings of hallucinations have not reflected the phenomenological complexity of AVHs in their experimental designs and theoretical framework. The second example, based on Jones (Schizophr Bull, in press, 2010 ), involves a critical examination of the phenomenology of AVHs in the context of two other prominent cognitive models: inner speech and intrusions from memory. It will be shown that, for both examples, the integration of a phenomenological analysis provides important improvements both on a methodological, theoretical and clinical level. This will be followed by insights and critiques from philosophy and clinical psychiatry—both of which offer a phenomenological alternative to the empiricist–rationalist conceptualisation of AVHs inherent to the cognitive sciences approach. Finally, the paper will conclude with ideas as to how the cognitive sciences may integrate these latter perspectives into their methodological and theoretical programmes. (shrink)
As our chief aim is a comprehensive theory of perception which will cover all the facts, ... JR Smythies' Analysis of Perception I discuss in Ch. VI, § 6. ...
Most accounts of veridical perception draw upon conventional causal theories of perception for an explanatory framework. Recently developed enactive or sensorimotor theories of perception pose a challenge to such accounts, necessitating a redefinition of veridical perception. I propose and defend one such definition, drawing upon empirical studies of perception, the resources of the enactive approach and phenomenology. I argue that perceptual experience engages an organism in a network of sensorimotor dependencies with the perceived object, and that veridical perceptions involve experiential (...) mastery of these dependencies. A thought example involving the phoneme restoration effect is used to compare this definition favourably with traditional accounts of veridical perception that involve the generation of matching content with appropriate causal history or patterns of counterfactual dependence. I also defend my account of veridical perception against several objections. (shrink)
INTRODUCTION This book is a systematic study of the problem of perception and knowledge. I intend to analyze the problem, to expound and criticize the most ...
What we perceive is the product of an intrinsic process and not part of external physical reality. This notion is consistent with the philosophical position of transcendental idealism but also agrees with physiological findings on the thalamocortical system. -Frequency rhythms of discharge activity from thalamic and cortical neurons are facilitated by cholinergic arousal and resonate in thalamocortical networks, thereby transiently forming assemblies of coherent oscillations under constraints of sensory input and prefrontal attentional mechanisms. Perception and conscious experience may be based (...) on such assemblies and sensory input to thalamic nuclei plays merely a constraining role in their formation. In schizophrenia, the ability of sensory input to modulate self-organisation of thalamocortical activity may be generally reduced. If during arousal thalamocortical self-organisation is underconstrained by sensory input, then attentional mechanisms alone may determine the content of perception and hallucinations may arise. (shrink)
As many as two million people in the United Kingdom repeatedly see people, animals, and objects that have no objective reality. Hallucinations on the border of sleep, dementing illnesses, delirium, eye disease, and schizophrenia account for 90% of these. The remainder have rarer disorders. We review existing models of recurrent complex visual hallucinations (RCVH) in the awake person, including cortical irritation, cortical hyperexcitability and cortical release, top-down activation, misperception, dream intrusion, and interactive models. We provide evidence that these can neither (...) fully account for the phenomenology of RCVH, nor for variations in the frequency of RCVH in different disorders. We propose a novel Perception and Attention Deficit (PAD) model for RCVH. A combination of impaired attentional binding and poor sensory activation of a correct proto-object, in conjunction with a relatively intact scene representation, bias perception to allow the intrusion of a hallucinatory proto-object into a scene perception. Incorporation of this image into a context-specific hallucinatory scene representation accounts for repetitive hallucinations. We suggest that these impairments are underpinned by disturbances in a lateral frontal cortex–ventral visual stream system. We show how the frequency of RCVH in different diseases is related to the coexistence of attentional and visual perceptual impairments; how attentional and perceptual processes can account for their phenomenology; and that diseases and other states with high rates of RCVH have cholinergic dysfunction in both frontal cortex and the ventral visual stream. Several tests of the model are indicated, together with a number of treatment options that it generates. Key Words: Blindness; Charles Bonnet; cholinergic; cortical release; delirium; dementia; dream intrusion; hallucination; Perception and Attention Deficit (PAD) model; schizophrenia. (shrink)
It is common both in philosophy and in the cognitive sciences (broadly understood as ranging from, say, neuroscience to developmental or evolutionary psychology) to distinguish between two kinds of hallucinations.1 What differentiates them is whether they are subjectively indistinguishable from genuine perceptions and therefore mistaken by us for the latter. While perceptual (or ‘true’) hallucinations cannot, from the subject’s perspective, be told apart from perceptions, non-perceptual (or ‘pseudo’) hallucinations can and usually are. Sometimes, when subjects, say, auditorily hallucinate someone else (...) calling their name or commenting on their behaviour, they are able to realise, on the basis of how they subjectively experience their episode of hallucination, that they are not perceiving real speech: their hallucination is non-perceptual. This happens, for instance, when subjects suffering from schizophrenia or other illnesses hear ‘inner voices’ speaking to them. But in other circumstances, the subjects concerned are - even under conditions of proper mental health and rationality - in no position to recognise the hallucinatory status of their experience without the help of some external evidence: their hallucination is perceptual. Wrongly hearing the phone ringing while taking a shower, say, is a good example of this kind of hallucination.2 When philosophers speak or write about hallucinations, they usually concentrate on perceptual hallucinations. One reason for this is the fact that philosophers tend to address the topic of hallucination, not for its own sake, but only in the context of some wider issues. Thus, when they are discussing hallucinations, they are primarily interested in other topics, such a how - or whether - we are able to acquire knowledge about the external world, in which sense our mental states are directed at objects and properties, how best to account for what our experiences are subjectively like, which features suffice for something to count as a conscious experience, and so on.. (shrink)
A comprehensive theory of the structure and cognitive function of the human imagination, and its relationship to perceptual experience, is developed, largely through a critique of the account propounded in Colin McGinn's Mindsight. McGinn eschews the highly deflationary (and unilluminating) views of imagination common amongst analytical philosophers, but fails to develop his own account satisfactorily because (owing to a scientifically outmoded understanding of visual perception) he draws an excessively sharp, qualitative distinction between imagination and perception (following Wittgenstein, Sartre, and others), (...) and because of his fatally flawed, empirically ungrounded conception of hallucination. In fact, however, an understanding of perception informed by modern visual science will enable us to unify our accounts of perception, mental imagery, dreaming, hallucination, creativity, and other aspects of imagination within a single coherent theoretical framework. (shrink)
When philosophers speak or write about hallucinations, they usually have perceptual (or ’true’) hallucinations in mind - that is, hallucinations which the subject mistakes for genuine perceptions and which have the same impact on his mental lives as the latter.1 One reason for this is the fact that philosophers tend to address the topic of hallucination, not for its own sake, but only in the context of some wider issues. Thus, when they are discussing hallucinations, they are primarily interested (...) in other topics, such a how - or whether - we are able to acquire knowledge about the external world, in which sense our mental states are directed at objects and properties, how best to account for what our experiences are subjectively like, which features suffice for something to count as a conscious experience, and so on. Especially the epistemic question, but also the connected issues in the philosophy of mind, lead them first of all to the phenomenon of genuine perception. For perceptions are precisely those mental episodes which point us to, and bring us into contact with, the world; and they also constitute the paradigm examples of conscious episodes with a distinctive phenomenal character. Hallucinations, on the other hand, do neither. Instead, they become relevant for the epistemic and related considerations only in so far as they give rise to sceptical scenarios and cast doubt on the common-sense (or naive) conception of the nature of perceptual experiences. And, in both cases, only those hallucinations matter which are indistinguishable from genuine perceptions with respect to their content and character.2 In the cognitive sciences (broadly understood as ranging from, say, neuroscience to developmental or evolutionary psychology), by contrast, hallucinations are much more prominent objects of study, and moreover objects of study in their own right. From the perspective of empirical investigations of the brain and mind - whether they utilise neuroimaging, observe behaviour, or examine verbal reports - hallucinations simply form one class of mental phenomena among many, all of which are ultimately in the same need of being studied and accounted for as part of our attempt to come to a full understanding of how our psychology works and is neurally realised.. (shrink)
