There is evidence from neuropsychological and psychophysical measurements that conscious sensory information is processed in discrete time segments. The segmentation process may be described as neuronal activity at a frequency of 40 Hz. Stimulus-induced neuronal activities of this frequency are found in the middle latency range of the auditory evoked potential . First, we have studied the effects of different general anesthetics on MLAEP and auditory evoked 40-Hz activity. Second, we investigated MLAEP and explicit and implicit memory for information presented (...) during cardiac anesthesia. In the awake patients peak latencies of the MLAEP were in the normal range. An auditory evoked 40-Hz activity was present 20–100 ms poststimulus. Under nonspecific anesthetics MLAEP and the 40-Hz activity were suppressed, and under receptor-specific agents MLAEP and the 40-Hz activity were partly preserved. None of the cardiac patients had conscious explicit recall of the intraoperative events, whereas some patients showed unconscious implicit memory for an intraoperative tape message. The implicit memory could be related to midlatency auditory evoked potentials. No implicit memory was detectable when MLAEP and the primary cortical processing of the auditory stimuli and 40-Hz activity were blocked. Implicit memory could be detected in more than 50% of the cases when MLAEP, a 30-Hz activity, and the primary cortical stimulus processing were preserved. In conclusion, our observations support the view that a high frequency oscillatory mechanisms, recorded as a grouped neuronal activity in the MLAEP, may be part of a basic neuronal program for conscious sensory information processing. (shrink)

Theories of binding have recently come into the focus of the consciousness debate. In this review, we discuss the potential relevance of temporal binding mechanisms for sensory awareness. Specifically, we suggest that neural synchrony with a precision in the millisecond range may be crucial for conscious processing, and may be involved in arousal, perceptual integration, attentional selection and working memory. Recent evidence from both animal and human studies demonstrates that specific changes in neuronal synchrony occur during all of these (...) processes and that they are distinguished by the emergence of fast oscillations with frequencies in the gamma-range. (shrink)

There has been an explosion of work on consciousness in the last 30–40 years from philosophers, psychologists, and neurologists. Thus, there is a need for an interdisciplinary, comprehensive volume in the field that brings together contributions from a wide range of experts on fundamental and cutting-edge topics. The Routledge Handbook of Consciousness fills this need and makes each chapter’s importance understandable to students and researchers from a variety of backgrounds. Designed to complement and better explain primary sources, this (...) volume is a valuable "first-stop" publication for undergraduate or graduate students enrolled in any course on "Consciousness," "Philosophy of Mind," or "Philosophy of Psychology," as well as a valuable handbook for researchers in these fields who want a useful reference to have close at hand. The 34 chapters, all published here for the first time, are divided into three parts: Part I covers the "History and Background Metaphysics" of consciousness, such as dualism, materialism, free will, and personal identity, and includes a chapter on Indian philosophy. Part II is on specific "Contemporary Theories of Consciousness," with chapters on representational, information integration, global workspace, attention-based, and quantum theories. Part III is entitled "Major Topics in Consciousness Research," with chapters on psychopathologies, dreaming, meditation, time, action, emotion, multisensory experience, animal and robot consciousness, and the unity of consciousness. -/- Each chapter begins with a brief introduction and concludes with a list of "Related Topics," as well as a list of "References," making the volume indispensable for the newcomer and experienced researcher alike. (shrink)

Impressions, energy radiated by phenomena in the momentary environmental scene, enter sensory neurons, creating in afferent nerves a data stream. Following Kant, by our inner sense the mind perceives its own thoughts as it ties together sense data into an internalized scene. The mind, residing in the brain, logically a Language Machine, processes and stores items as coded grammatical entities. Kantian synthetic unity in the linguistic brain is able to deliver our experience of the scene as we appear to see (...) it. Uniquely, the brain records its own history, synthesizing a Movie-in-the-Brain, called the Noumenal Cosmos. Attempting thereby to represent the actual Universe, this makes for a sovereign brain that governs itself. The brain is domicile of an Ego, with its selfhood at stake at all times. Yet, it can know itself only by its actions, in which it appears as an actor in its own movie. Phenomena enter garbled, as confused apparitions, and must be put in good form using top–down feedback control by Ego, so that each movie frame makes rational sense within the overall context of the Noumenal Cosmos. A stack of frames is processed typically in 40 Hz rhythm with 300 ms process time each, for about 12 in the stack at any time. Successive neural centers are processing the stack in the brain assembly line, based on data from increasingly global receptive fields. Ego stitches together the movie frames, but only the top frame is in consciousness for 25 ms. The top frame contains the whole scene where the Ego makes an appearance as the actor that imposes Kantian synthetic unity on the scene, merely an assembly of grammatical texts, in a system-internal coded process language, fitting the scene into the Noumenal Cosmos. But Ego observes Ego only to the extent permitted by the objectivity rule, only what it does and thinks, not its true face. From the Noumenal Cosmos, the Ego receives grammatical messages in the internal sense code. They are integrated into a whole in the reaction of the Ego to the momentary scene. The voluntary nature of Ego’s decisions is explained, based on its ability to code in advance its own actions sequentially in time, as it sees fit with a view to an orderly Noumenal Cosmos, records of code being arranged spatially in neural structures. (shrink)

Human consciousness is widely understood to be underpinned by rich and diverse functional networks, whose breakdown results in unconsciousness. Candidate neural correlates of anesthetic-induced unconsciousness include: (1) disrupted frontoparietal functional connectivity; (2) disrupted brain network hubs; and (3) reduced spatiotemporal complexity. However, emerging counterexamples have revealed that these markers may appear outside of the state they are associated with, challenging both their inclusion as markers of conscious level, and the theories of consciousness that rely on their evidence. In (...) this study, we present a case series of three individuals in disorders of consciousness (DOC) who exhibit paradoxical brain responses to exposure to anesthesia. High-density electroencephalographic data were recorded from three patients with unresponsive wakefulness syndrome (UWS) while they underwent a protocol of propofol anesthesia with a targeted effect site concentration of 2 μg/ml. Network hubs and directionality of functional connectivity in the alpha frequency band (8–13 Hz), were estimated using the weighted phase lag index (wPLI) and directed phase lag index (dPLI). The spatiotemporal signal complexity was estimated using three types of Lempel-Ziv complexity (LZC). Our results illustrate that exposure to propofol anesthesia can paradoxically result in: (1) increased frontoparietal feedback-dominant connectivity; (2) posterior network hubs; and (3) increased spatiotemporal complexity. The case examples presented in this paper challenge the role of functional connectivity and spatiotemporal complexity in theories of consciousness and for the clinical evaluation of levels of human consciousness. (shrink)

This essay surveys representationalist theories of phenomenal consciousness as well as the major arguments for them. It also takes up two major objections. The essay is divided into five sections. Section I offers some introductory remarks on phenomenal consciousness. Section II presents the classic view of phenomenal consciousness to which representationalists are opposed. Section III canvasses various versions of representationalism about consciousness. Section IV lays out the main arguments for the representationalist stance. The final section addresses (...) the two objections. (shrink)

This chapter surveys current approaches to consciousness in Anglo-American analytic philosophy. It focuses on five approaches, to which I will refer as mysterianism, dualism, representationalism, higher-order monitoring theory, and self-representationalism. With each approach, I will present in order the leading account of consciousness along its line, the case for the approach, and the case against the approach. I will not issue a final verdict on any approach, though by the end of the chapter it should be evident (...) where my own sympathies lie. (shrink)

Conscious experience is one of the most difficult and thorny problems in psychological science. Its study has been neglected for many years, either because it was thought to be too difficult, or because the relevant evidence was thought to be poor. Bernard Baars suggests a way to specify empirical constraints on a theory of consciousness by contrasting well-established conscious phenomena - such as stimulus representations known to be attended, perceptual, and informative - with closely comparable unconscious ones - (...) such as stimulus representations known to be preperceptual, unattended, or habituated. Adducing data to show that consciousness is associated with a kind of global workplace in the nervous system, and that several brain structures are known to behave in accordance with his theory, Baars helps to clarify many difficult problems. (shrink)

One of the promising approaches to the problem of consciousness has been the Higher-Order Monitoring Theory of Consciousness. According to the Higher-Order Monitoring Theory, a mental state M of a subject S is conscious iff S has another mental state, M*, such that M* is an appropriate representation of M. Recently, several philosophers have developed a Higher-Order Monitoring theory with a twist. The twist is that M and M* are construed as entertaining some kind of (...) constitutive relation, rather than being logically independent of each other. We may call this the Same-Order Monitoring Theory of Consciousness. In this paper, I discuss the nature of the Same-Order Monitoring Theory and argue for its superiority over the more traditional Higher-Order Monitoring Theory. (shrink)

Very plausibly, nothing can be a genuine computing system unless it meets an input-sensitivity requirement. Otherwise all sorts of objects, such as rocks or pails of water, can count as performing computations, even such as might suffice for mentality—thus threatening computationalism about the mind with panpsychism. Maudlin in J Philos 86:407–432, ( 1989 ) and Bishop ( 2002a , b ) have argued, however, that such a requirement creates difficulties for computationalism about conscious experience, putting it in conflict with the (...) very intuitive thesis that conscious experience supervenes on physical activity. Klein in Synthese 165:141–153, ( 2008 ) proposes a way for computationalists about experience to avoid panpsychism while still respecting the supervenience of experience on activity. I argue that his attempt to save computational theories of experience from Maudlin’s and Bishop’s critique fails. (shrink)

The scientific study of consciousness emerged as an organized field of research only a few decades ago. As empirical results have begun to enhance our understanding of consciousness, it is important to find out whether other factors, such as funding for consciousness research and status of consciousness scientists, provide a suitable environment for the field to grow and develop sustainably. We conducted an online survey on people’s views regarding various aspects of the scientific study of (...) class='Hi'>consciousness as a field of research. 249 participants completed the survey, among which 80% were in academia, and around 40% were experts in consciousness research. Topics covered include the progress made by the field, funding for consciousness research, job opportunities for consciousness researchers, and the scientific rigor of the work done by researchers in the field. The majority of respondents (78%) indicated that scientific research on consciousness has been making progress. However, most participants perceived obtaining funding and getting a job in the field of consciousness research as more difficult than in other subfields of neuroscience. Overall, work done in consciousness research was perceived to be less rigorous than other neuroscience subfields, but this perceived lack of rigor was not related to the perceived difficulty in finding jobs and obtaining funding. Lastly, we found that, overall, the global workspace theory was perceived to be the most promising (around 28%), while most non-expert researchers (around 22% of non-experts) found the integrated information theory (IIT) most promising. We believe the survey results provide an interesting picture of current opinions from scientists and researchers about the progresses made and the challenges faced by consciousness research as an independent field. They will inspire collective reflection on the future directions regarding funding and job opportunities for the field. (shrink)

Theories of Consciousness provides an introduction to a variety of approaches to consciousness, questions the nature of consciousness, and contributes to current debates about whether a scientific understanding of consciousness is possible. While discussing key figures including Descartes, Fodor, Dennett and Chalmers, the book incorporates identity theories, representational theories, intentionality, externalism and new information-based theories.

The most remarkable fact about the universe is that certain parts of it are conscious. Somehow nature has managed to pull the rabbit of experience out of a hat made of mere matter. Making its own contribution to the current, lively debate about the nature of consciousness, Theories of Consciousness introduces variety of approaches to consciousness and explores to what extent scientific understanding of consciousness is possible. Including discussion of key figures, such as Descartes, Foder, Dennett (...) and Chalmers, the book covers identity theories, representational theories, intentionality, externalism, and the new information-based theories. (shrink)

When the cognitive neuroscience of consciousness is finally written, it will likely have many of the elements documented in this fine book. My review is relatively detailed because, out of fourteen authors of the eight articles in this book, only four have previously appeared in the Journal of Consciousness Studies. Stanislas Dehaene , The Cognitive Neuroscience of Consciousness Cambridge, MA: MIT Press, 2001, pp. 243 price $40.00 ISBN 0-262-54131-9.

The idea of representation has been central in discussions of intentionality for many years. But only more recently has it begun playing a wider role in the philosophy of mind, particularly in theories of consciousness. Indeed, there are now multiple representational theories of consciousness, corresponding to different uses of the term "conscious," each attempting to explain the corresponding phenomenon in terms of representation. More cautiously, each theory attempts to explain its target phenomenon in terms of _intentionality_, and (...) assumes that intentionality is representation. (shrink)

This article compares the three frameworks for theories of consciousness that are taken most seriously by neuroscientists, the view that consciousness is a biological state of the brain, the global workspace perspective and an account in terms of higher order states. The comparison features the “explanatory gap” (Nagel, 1974; Levine, 1983) the fact that we have no idea why the neural basis of an experience is the neural basis of that experience rather than another experience or no experience (...) at all. It is argued that the biological framework handles the explanatory gap better than the global workspace of higher order views. The article does not discuss quantum theories or “panpsychist” accounts according to which consciousness is a feature of the smallest particles of inorganic matter (Chalmers, 1996; Rosenberg, 2004). Nor does it discuss the “representationist” proposals (Tye, 2000; Byrne, 2001a) that are popular among philosophers but not neuroscientists. (shrink)

This paper provides a brief introduction to quantum theory and the proceeds to discuss the different ways in which the relationship between quantum theory and mind/consciousness is seen in some of the main alternative interpretations of quantum theory namely by Bohr; von Neumann; Penrose: Everett; and Bohm and Hiley. It briefly considers how qualia might be explained in a quantum framework, and makes a connection to research on quantum biology, quantum cognition and quantum computation. The paper (...) notes that it is widely agreed that conscious experience has dynamical and holistic features. It asks whether these features might in some way be a reflection of the dynamic and holistic quantum physical processes associated with the brain that may underlie (and make possible) the more mechanistic neurophysiological processes that contemporary cognitive neuroscience is measuring. If so, these macroscopic processes would be a kind of shadow, or amplification of the results of quantum processes at a deeper (pre-spatial or "implicate") level where our minds and conscious experience essentially live and unfold. The macroscopic, mechanistic level is of course necessary for communication, cognition and life as we know it, including science; but perhaps the experiencing (consciousness) of that world and the initiation of our actions takes place at a more subtle, non-mechanical level of the physical world, which quantum theory has begun to discover. At the very least a quantum perspective will help a “classical” consciousness theorist to become better aware of some of the hidden assumptions in his or her approach. Given that consciousness is widely thought to be a “hard” problem, its solution may well require us to question and revise some of our assumptions that now seem to us completely obvious. This is what quantum theory is all about – learning, on the basis of scientific experiments, to question the “obvious” truths about the nature of the physical world and to come up with more coherent alternatives. (shrink)

Using empirical research on pain, sound and taste, I argue against the combination of intentionalism about consciousness and a broadly ‘tracking’ psychosemantics of the kind defended by Fodor, Dretske, Hill, Neander, Stalnaker, Tye and others. Then I develop problems with Kriegel and Prinz's attempt to combine a Dretskean psychosemantics with the view that sensible properties are Shoemakerian response-dependent properties. Finally, I develop in detail my own 'primitivist' view of sensory intentionality.

Many people have thought that consciousness.

Phenomenal consciousness is the property mental states, events, and processes have when, and only when, there is something it is like for their subject to undergo them, or be in them. What it is like to have a conscious experience is customarily referred to as the experience’s phenomenal character. Theories of consciousness attempt to account for this phenomenal character. This article surveys the currently prominent theories, paying special attention to the various attempts to explain a state’s phenomenal character (...) in terms of its representational content. (shrink)

A satisfactory solution to the problem of consciousness would take the form of a simple yet fully general model that specifies the precise conditions under which any given state of consciousness occurs. Science has uncovered numerous correlations between consciousness and neural activity, but it has not yet come anywhere close to this. We are still looking for the Newtonian laws of consciousness. -/- One of the main difficulties with consciousness is that we lack a language (...) in which to formulate illuminating generalizations about it. Philosophers and scientists talk about "what it’s like", sensations, feelings, and perceptual states such as seeing and hearing. This language does not allow a precise articulation of the internal structures of conscious states and their inter-relations. It is inadequate to capture relations of the kind we are looking for between conscious states and physical states. -/- In this thesis I refine and defend a theory of consciousness which promises to solve this regimentation problem: the representational theory of consciousness. I argue that the representational theory can solve the regimentation problem and smooth out other important obstacles to a fruitful study of consciousness. I also make a case for the theory independently of its payoffs, and I discuss the leading opposing theories at some length. (shrink)

My target in this paper is "theories of consciousness". There are many theories of consciousness around, and my view is that they are all misconceived. Consciousness is not a normal scientific subject, and needs handling with special care. It is foolhardy to jump straight in and start building a theory, as if consciousness were just like electricity or chemical valency. We will do much better to reflect explicitly on our methodology first. When we do this, (...) we will see that theories of consciousness are trying to answer a question that isn't there. (shrink)

A core commitment of the reflexive theory of consciousness is that conscious states are themselves necessarily the contents of mental states. The strongest argument for this claim—the necessity of inner-content for consciousness—is the argument from unconscious perception. According to this argument, we find evidence for the necessity claim from cases of alleged unconscious perception, the most well-known and widely discussed of these being blindsight. However, the reflexive theory cannot partake in this argument and therefore, must rely (...) on at least one of the other arguments for the necessity claim. These arguments are significantly less convincing than the argument from unconscious perception, and thus the reflexive theory is left in a dialectically weak position. (shrink)

Ambitious higher-order theories of consciousness aim to account for conscious states when these are understood in terms of what-it-is-like-ness. This paper considers two arguments concerning this aim, and concludes that ambitious theories fail. The misrepresentation argument against HO theories aims to show that the possibility of radical misrepresentation—there being a HO state about a state the subject is not in—leads to a contradiction. In contrast, the awareness argument aims to bolster HO theories by showing that subjects are aware of (...) all their conscious states. Both arguments hinge on how we understand two related notions which are ubiquitous in discussions of consciousness: those of what-it-is-like-ness and there being something it is like for a subject to be in a mental state. This paper examines how HO theorists must understand the two crucial notions if they are to reject the misrepresentation argument but assert the awareness argument. It shows that HO theorists can and do adopt an understanding—the HO reading—which seems to give them what they want. But adopting the HO reading changes the two arguments. On this reading, the awareness argument tells us nothing about those states there is something it is like to be in, and so offers no support to ambitious HO theories. And to respond to the misrepresentation understood according to the HO reading is to simply ignore the argument presented, and so to give no response at all. As things stand, we should deny that HO theories can account for what-it-is-like-ness. (shrink)

The paper contains an argument against functionalist theories of consciousness. The argument exploits an intuition to the effect that parts of an individual's brain that are not in use at a time t, can have no bearing on whether that individual is conscious at t. After presenting the argument, I defend it against two possible objections, and then distinguish it from two arguments to which it appears, on the surface to be similar.

Consciousness has traditionally been the subject matter of philosophy. However, especially in recent years, various branches of science have attempted to develop theories of consciousness. I evaluate the biological theories of Francis Crick, Gerald Edelman, and Antti Revonsuo in order to gauge the current state of biological accounts of consciousness. I begin with an explication of the easy and hard problems of consciousness as defined by David Chalmers. Next, I summarize how each theory defines ‘ (...) class='Hi'>consciousness’ and then I evaluate each theoretical model. Finally, I evaluate the models in terms of the easy problems and, especially, the hard problem. My aim in this work is to demonstrate that the current biological theories of consciousness are inadequate. This claim is not tantamount to one that claims that the theories are ineffective. On the contrary, these theories tend to be more useful than not. However, these biological models do not address the most essential component of consciousness that is subjective phenomenological experience. (shrink)

This article presents the case for an approach to consciousness that I call illusionism. This is the view that phenomenal consciousness, as usually conceived, is illusory. According to illusionists, our sense that it is like something to undergo conscious experiences is due to the fact that we systematically misrepresent them as having phenomenal properties. Thus, the task for a theory of consciousness is to explain our illusory representations of phenomenality, not phenomenality itself, and the hard problem (...) is replaced by the illusion problem. Although it has had powerful defenders, illusionism remains a minority position, and it is often dismissed as failing to take consciousness seriously. This article seeks to rebut this accusation. It defines the illusionist programme, outlines its attractions, and defends it against some common objections. It concludes that illusionism is a coherent and attractive approach, which deserves serious consideration. (shrink)

In its recent history, the philosophy of mind has come to resemble an entry into the genre of Hammer horror or pulpy science fiction. These days it is unusual to encounter a major philosophical work on the mind that is not populated with bats, homunculi, swamp-creatures, cruelly imprisoned genius scientists, aliens, cyborgs, other-worldly twins, self-aware Computer programs, Frankenstein-monster-like ‘Blockheads,’ or zombies. The purpose of this paper is to review the role in the philosophy of mind of one of these fantastic (...) thought-experiments — the zombie — and to reassess the implications of zombie arguments, which I will suggest have been widely misinterpreted. I shall argue that zombies, far from being the enemy of materialism, are its friend; and furthermore that zombies militate against the computational model of consciousness and in favour of more biologically-rooted conceptions, and hence that zombie- considerations support a morereductivekind of physicalism about consciousness than has been in vogue in recent years. (shrink)

In this discussion paper, I argue that no theory of consciousness can simultaneously respect four initially plausible metaphysical claims – namely, “first-person realism”, “non-solipsism”, “non-fragmentation”, and “one world” – but that any three of the four claims are mutually consistent. So, theories of consciousness face a “quadrilemma”. Since it will be hard to achieve a consensus on which of the four claims to retain and which to give up, we arrive at a landscape of competing theories, all (...) of which have pros and cons. I will briefly indicate which kinds of theories correspond to the four horns of the quadrilemma. (shrink)

In this paper I argue that the Integrated Information Theory of Consciousness has an underlying emergentist metaphysics, specifically of a kind that has received minimal attention and we may call functionalist emergentism. I will try to show that in this scientific theory conscious experience is a functional-role property possessed by the whole system, not by their parts, which is dependent on, but also (purportedly) causally powerful over and above, the properties of the parts. However, I will argue (...) that depicting conscious experience as a functional-role emergent property threatens the whole coherence of the theory because, by definition, functional-realizers do all the causal work associated with the instantiation of any functional-role property on any occasion. Hence, to preserve the causal power of consciousness, which, as we will see, is one of the fundamental building blocks of the theory, linked to the assertion of the very existence of consciousness, phenomenal properties should be re-thought as realizers of the relevant informationally integrated causal-roles. (shrink)

This paper sketches a new and somewhat heterodox metaphysical theory of consciousness: the “many-worlds theory”. It drops the assumption that all conscious subjects’ experiences are features of one and the same world and instead associates different subjects with different “first-personally centred worlds”. We can think of these as distinct “first-personal realizers” of a shared “third-personal world”, where the latter is supervenient, in a sense to be explained. This is combined with a form of modal realism, according to (...) which different subjects’ first-personally centred worlds are all real, though only one of them is present for each subject. The theory offers a novel way of capturing the irreducibly subjective nature of conscious experience without lapsing into solipsism. The paper also looks at some scientific theories of consciousness, such as integrated information theory, through the proposed lens and reconsiders the hard problem of consciousness. (shrink)

The Integrated Information Theory is a leading scientific theory of consciousness, which implies a kind of panpsychism. In this paper, I consider whether IIT is compatible with a particular kind of panpsychism, known as Russellian panpsychism, which purports to avoid the main problems of both physicalism and dualism. I will first show that if IIT were compatible with Russellian panpsychism, it would contribute to solving Russellian panpsychism’s combination problem, which threatens to show that the view does not (...) avoid the main problems of physicalism and dualism after all. I then show that the theories are not compatible as they currently stand, in view of what I call the coarse-graining problem. After I explain the coarse-graining problem, I will offer two possible solutions, each involving a small modification of IIT. Given either of these modifications, IIT and Russellian panpsychism may be fully compatible after all, and jointly enable significant progress on the mind–body problem. (shrink)

According to (what I will call) an inner awareness theory of consciousness, you are in a (phenomenally) conscious state only if you are aware, in some sense, of your being in the state. This theory is widely held, but what arguments are there for holding it? In this paper, I gather together in a systematic way the main arguments for holding the theory and suggest that none of them is persuasive. I end the paper by asking (...) what our attitude to the theory should be if there is no existing argument for it. (shrink)

ABSTRACTAmbitious Higher-order theories of consciousness – Higher-order theories that purport to give an account of phenomenal consciousness – face a well-known objection from the possibility of ra...

An overview of higher-order representational theories of consciousness. Representational theories of consciousness attempt to reduce consciousness to “mental representations” rather than directly to neural or other physical states. This approach has been fairly popular over the past few decades. Examples include first-order representationalism (FOR) which attempts to explain conscious experience primarily in terms of world-directed (or first-order) intentional states (Tye 2005) as well as several versions of higher-order representationalism (HOR) which holds that what makes a mental state (...) M conscious is that it is the object of some kind of higher-order mental state directed at M. The primary focus of this entry is on HOR and especially higher-order thought (HOT) theory. The key question that should be answered by any theory of consciousness is: What makes a mental state a conscious mental state? Section 1 introduces the overall representationalist approach to consciousness and briefly discuss Tye’s FOR. Section 2 presents three major versions of HOR: higher-order thought theory, dispositional higher-order thought theory, and higher-order perception theory. In section 3, a number of common and important objections and replies are presented. Section 4 briefly outlines a close connection between HOT theory and conceptualism, that is, the claim that the representational content of a perceptual experience is entirely determined by the conceptual capacities the perceiver brings to bear in her experience. Section 5 examines several hybrid higher-order and “self-representational” theories of consciousness which all hold that conscious states are self-directed in some way. Section 6 addresses the potentially damaging claim that HOT theory requires neural activity in the prefrontal cortex (PFC) in order for one to have conscious states. (shrink)