Over the past several years, the study of self-related cognition has garnered increasing interest amongst psychologists and cognitive neuroscientists. Concomitantly, lesion and neuroimaging studies have demonstrated the importance of intact cortico-cortical and cortico-subcortical connections for supporting high-level cognitive functions. Commissurotomy or “split-brain” patients provide unique insights into the role of the cerebral commissures in maintaining an individual’s sense of self, as well as into the unique self-representation capabilities of each cerebral hemisphere. Here we review empirical work examining the integrity of (...) self-related processes in patients with various disconnection syndromes, focusing on studies of self-recognition, ownership, and agency. Taken together, this body of work suggests that an intact corpus callosum enabling interhemispheric transfer is necessary for some, but not all types of self-representations. (shrink)

To assess the ability of the disconnected cerebral hemispheres to recognize images of the self, a split-brain patient was tested using morphed self-face images presented to one visual hemifield at a time while making “self/other” judgments. The performance of the right and left hemispheres of this patient as assessed by a signal detection method was not significantly different, though a measure of bias did reveal hemispheric differences. The right and left hemispheres of this patient independently and equally possessed the ability (...) to self-recognize, but only the right hemisphere could successfully recognize familiar others. This supports a modular concept of self-recognition and other-recognition, separately present in each cerebral hemisphere. (shrink)

The clinical and para-clinical examination of residual self-consciousness in non-communicative severely brain damaged patients remains exceptionally challenging. Passive presentation of the patient’s own name and own face are known to be effective attention-grabbing stimuli when clinically assessing consciousness at the patient’s bedside. Event-related potential and functional neuroimaging studies using such self-referential stimuli are currently being used to disentangle the cognitive hierarchy of self-processing. We here review neuropsychological, neuropathological, electrophysiological and neuroimaging studies using the own name and own face paradigm obtained (...) in conscious waking, sleep, pharmacological coma, pathological coma and related disorders of consciousness. Based on these results we discuss what we currently do and do not know about the functional significance of the neural network involved in “automatic” and “conscious” self-referential processing. (shrink)

Consciousness in experimental subjects is typically inferred from reports and other forms of voluntary behaviour. A wealth of everyday experience confirms that healthy subjects do not ordinarily behave in these ways unless they are conscious. Investigation of consciousness in vegetative state patients has been based on the search for neural evidence that such broad functional capacities are preserved in some vegetative state patients. We call this the standard approach. To date, the results of the standard approach have suggested that some (...) vegetative state patients might indeed be conscious, although they fall short of being demonstrative. The fact that some vegetative state patients show evidence of consciousness according to the standard approach is remarkable, for the standard approach to consciousness is rather conservative, and leaves open the pressing question of how to ascertain whether patients who fail such tests are conscious or not. We argue for a cluster-based ‘natural kind’ methodology that is adequate to that task, both as a replacement for the approach that currently informs research into the presence or absence of consciousness in vegetative state patients and as a methodology for the science of consciousness more generally. 1. Introduction2. The Vegetative State3. The Standard Approach4. The Natural Kind Methodology5. Is Consciousness a Special Case? 5.1 Is consciousness a natural kind?5.2 A special obstacle?6. Conclusion. (shrink)

: This paper argues for a distinction between possession of a unified consciousness and possession of a single stream of consciousness. Although the distinction has widespread applicability in discussions of the structure of consciousness and of pathologies of conscious experience, I will illustrate its importance primarily using the debate about consciousness in split-brain subjects, suggesting that those who have argued that split-brain subjects have two streams of consciousness apiece and those who have argued that they have a unified consciousness may (...) both be right. (shrink)

Some philosophers have argued that so long as two neural events, within a subject, are both of the same type and both carry the same content, then these events may jointly constitute a single mental token, regardless of the sort of causal relation to each other that they bear. These philosophers have used this claim—which I call the “singularity-through-redundancy” position—in order to argue that a split-brain subject normally has a single stream of consciousness, disjunctively realized across the two hemispheres. This (...) paper argues, against this position, that the kind of causal relations multiple neural events bear to each other constrains the mental tokens with which functionalists who are realists can identify them. (shrink)

Dual-Brain Psychology is a theory and its clinical applications that come out of the author's clinical observations and from the Split-brain Studies. The theory posits, based on decades of rigorous, peer-reviewed experiments and clinical reports, that, in most patients, one brain's cerebral hemisphere when stimulated by simple lateral visual field stimulation, or unilateral transcranial photobiomodulation, reveals a dramatic change in personality such that stimulating one hemisphere evokes, as a trait, a personality that is more childlike and more presently affected by (...) childhood maltreatments that are usually not presently appreciated but are the proximal cause of the patient's symptoms. The personality associated with the other hemisphere is much more mature, less affected by the traumas, and less symptomatic. The theory can be applied to in-depth psychotherapy in which the focus is on helping the troubled side to bear and process the traumas with the help of the therapist and the healthier personality. A person's symptoms can be evoked to aid the psychotherapy with hemispheric stimulation and the relationship between the dual personalities can be transformed from conflicted and sabotaging to cooperating toward overall health. Stimulating the positive hemisphere in most therapy patients rapidly relieves symptoms such as anxiety, depression, or substance cravings. Two randomized controlled trials used unilateral transcranial photobiomodulation to the positive hemisphere as a stand-alone treatment for opioid cravings and both revealed high effect sizes. The theory is supported by brain imaging and rTMS studies. It is the first psychological theory and application that comes out of and is supported by rigorous peer-reviewed experimentation. (shrink)

In this commentaryI evaluate the claim made byKeenan, Nelson, OÕConnor, and Pascual-Leone (2001) that since self-recognition results from right hemispheric activity, self-awareness too is likely to be produced by the activity of the same hemisphere. This reasoning is based on the assumption that self-recognition represents a valid operationalization of self-awareness; I present two views that challenge this rationale. Keenan et al. also support their claim with published evidence relating brain activityand self-awareness; I closelyexamine their analysis of one specific review of (...) literature and conclude that it appears to be biased. Finally, recent research suggests that inner speech (which is associated with left hemispheric activity) is linked to self-awareness—an observation that further casts doubt on the existence of a right hemispheric self-awareness. Ó 2002 Elsevier Science (USA). All rights reserved. (shrink)

Localizing the self in the brain has been the goal of consciousness research for centuries. Recently, there has been an increase in attention to the localization of the self. Here we present data from patients suffering from a loss of self in an attempt to understand the neural correlates of consciousness. Focusing on delusional misidentification syndrome , we find that frontal regions, as well as the right hemisphere appear to play a significant role in DMS and DMS related disorders. These (...) data are placed in the context of neuroimaging findings. (shrink)

This paper presents a review of studies that were aimed at determining which brain regions are recruited during visual self-recognition, with a particular focus on self-face recognition. A complex bilateral network, involving frontal, parietal and occipital areas, appears to be associated with self-face recognition, with a particularly high implication of the right hemisphere. Results indicate that it remains difficult to determine which specific cognitive operation is reflected by each recruited brain area, in part due to the variability of used control (...) stimuli and experimental tasks. A synthesis of the interpretations provided by previous studies is presented. The relevance of using self-recognition as an indicator of self-awareness is discussed. We argue that a major aim of future research in the field should be to identify more clearly the cognitive operations induced by the perception of the self-face, and search for dissociations between neural correlates and cognitive components. (shrink)

In this dissertation, I examine the nature and structure of consciousness. Conscious experience is often said to be phenomenally unified, and subjects of consciousness are often self-conscious. I ask whether these features necessarily accompany conscious experience. Is it necessarily the case, for instance, that all of a conscious subject's experiences at a time are phenomenally unified? And is it necessarily the case that subjects of consciousness are self-conscious whenever they are conscious? I argue that the answer to the former is (...) affirmative and the latter negative. In the first chapter, I set the stage by distinguishing phenomenal unity from other species of conscious unity. A pair of conscious states is phenomenally unified if they are experienced together as part of a single experience that encompasses them both. In this and the next two chapters I defend the thesis that, necessarily, for any subject (of conscious mental states) at any time, all of that subject's conscious mental states (at that time) are part of a single, maximal state of consciousness. I call this thesis the "Unity Thesis." I proceed by considering some preliminary questions that might be raised about the Unity Thesis. For instance, the thesis presupposes that it is coherent to talk about parts of mental states. I consider objections by Tye and Searle and argue that the notion of an experiential part is unproblematic. In the remaining pages of the chapter, I present the source of the biggest challenge to the Unity Thesis: the data gathered from split-brain subjects. The Unity Thesis is formulated using the notion of a maximal state of consciousness. In the second chapter, I attempt to precisify this notion in a way that does not pre-emptively decide the debate over the Unity Thesis. In informal terms, a maximal state of consciousness is a sum of conscious states that are i) simultaneous, ii) have the same subject, and iii) all have a conjoint phenomenology. I call this the Consensus View. I then consider two unorthodox views that the Consensus View does not take off the table: the views that a "collective consciousness" and a "spread consciousness" are possible. A collective subject is one that can enjoy the experiences of an indeterminate number of "lesser" subjects of consciousness by sharing them together with those subjects. A spread subject is one that can enjoy the experiences of an indeterminate number of lesser subjects of consciousness, but it does so, not by sharing those experiences with the lesser subjects, but by absorbing the lesser subjects of experience into itself, thereby erasing the traditional boundaries between the entities we intuitively think of as subjects of experience. I argue that, although the Consensus View does not decide against them, these views stretch the bounds of coherence and should not, therefore, be accepted. Having presented an account of what maximal state of consciousness is, I define a stream of consciousness in terms of a maximal states of consciousness. In the rest of chapter two, I consider and argue against a number of different ways of interpreting the split-brain data that are either inconsistent with the Unity Thesis or attribute more than one subject of consciousness to split-brain subjects. Among the views I consider are Lockwood's partial-unity view and the views, by theorists such as Sperry, Koch, Puccetti, Marks, and Tye, that split-brain subjects have two non-overlapping streams of consciousness. In chapter three, I consider a recent attempt by Bayne to account for the split-brain data in a way that does not attribute two streams of consciousness to them. According to Bayne's Switch Model, the consciousness of split-brain subjects can be likened to that of a ball that is passed back and forth between the two hemispheres of the upper-brain. The hemispheres take turns supporting a single stream of consciousness. I consider the empirical data in some detail and argue that the data is not as compatible with the Switch Model as Bayne claims. I close the chapter by presenting the rough outline of an interpretation of the split-brain data that is consistent with both the Unity Thesis and the split-brain data. In chapter four, I turn from defending the Unity Thesis to examining an attempt to account for conscious unity. Rosenthal has offered a theory of conscious unity as an extension of his higher-order theory of consciousness. I consider his account of conscious unity in light of a well-known objection to his theory: the (Representational) Mismatch Objection. It can be asked what it is like for a subject of experience when a higher-order state misrepresents its target first-order state. If what it is like for the subject corresponds to the content of the higher-order state, then it appears as though higher-order representation is unnecessary for conscious experience, for it would appear as though it is possible for a state to be conscious without being represented by a higher-order state. If what it is like corresponds to the content of the lower-order state, then it would again seem as though representation at the higher-order level is unnecessary for conscious experience, for the higher-order state would not seem to be doing any work in generating the experience. I consider and argue against two recent defences of Rosenthal's higher-order theory from the Mismatch Objection. Then I turn to Rosenthal's account of conscious unity. Rosenthal's account posits two mental mechanisms. I refer to the ways of accounting for conscious unity via these two mechanisms as the "gathering strategy" and the "common-ascription strategy" respectively. Both of these strategies, I argue, appear to locate the basis for certain phenomenal facts in higher-order representational facts. This raises a prima facie question: does Rosenthal's account of conscious unity land him square within the sights of the Mismatch Objection? Although the gathering strategy may ultimately be understood in a way that does not make it subject to the Mismatch Objection, Rosenthal has certain commitments that bar this strategy from serving as a complete account of conscious unity. This is problematic for Rosenthal, I argue, because his common-ascription strategy faces some difficult questions. This strategy makes conscious unity due to an implicit expectation a subject of consciousness has that, whenever he or she engages in introspection, an explicit sense of conscious unity will be generated. I argue that it is very difficult to see how such an implicit sense could both avoid the Mismatch Objection and do the work it needs to do in order to account for conscious unity. In chapter five, the discussion turns from the unity of consciousness to self-consciousness. The question that is considered in this and the last chapter is the question whether conscious experience is necessarily accompanied by self-consciousness. The affirmative answer to this question I call the Ubiquity Thesis. I spend some time distinguishing robust conceptions of self-consciousness from minimal conceptions of self-consciousness. The notion of self-consciousness invoked by the Ubiquity Thesis is a minimal one. In spite of the fact that the Ubiquity Thesis invokes only a minimal or thin conception of self-consciousness, I believe the thesis to be false and argue against it. In this chapter I take up the views of Husserl. Husserl is often regarded as the progenitor of the phenomenological tradition, a tradition in which many philosophers affirm the Ubiquity Thesis. I examine and argue against an interpretation of Husserl's work, one defended by Zahavi, according to which Husserl could be seen to defend the Ubiquity Thesis. One claim that Husserl makes is that, in order for an object to become the intentional target of a conscious state, it must be given to consciousness beforehand. It is possible, during acts of deliberate introspection, for consciousness to take itself as its object. On Husserl's view, this requires consciousness to be given to itself beforehand. This self-givenness of consciousness, argues Zahavi, can be seen as a kind of minimal self-consciousness. Husserl has also offered an account of this self-givenness of consciousness and it appears in his discussion of inner time-consciousness. I attempt to argue, using some of Husserl's other views regarding psychological stances (or standpoints), that consciousness is not given to itself outside of the adoption of a certain psychological standpoint. I also offer an alternative way of accounting for inner time-consciousness, one that does not have, as a built-in feature, that consciousness always has itself as a secondary object. In the sixth and final chapter, I take up a contemporary defence of the Ubiquity Thesis. Kriegel, a higher-order theorist like Rosenthal, has argued that every conscious state is conscious in virtue of the fact that it represents itself. This self-representation is understood as a kind of self-consciousness and, thus, his theory can be seen as affirming the Ubiquity Thesis. In the first part of the chapter, I take issue with the way in which Kriegel lays out the conceptual terrain. In particular, Kriegel countenances a property he calls "intransitive state self-consciousness." I argue that this way of speaking is confused. I then turn to considering Kriegel's account. Kriegel identifies the species of self-consciousness that pervades all of conscious experience with a peripheral awareness of one's own mental states. I argue that such a peripheral inner awareness does not accompany all of our mental states and, thus, that Kriegel's views do not give us reason to accept the Ubiquity Thesis. (shrink)

This is a bibliography of books and articles on consciousness in philosophy, cognitive science, and neuroscience over the last 30 years. There are three main sections, devoted to monographs, edited collections of papers, and articles. The first two of these sections are each divided into three subsections containing books in each of the main areas of research. The third section is divided into 12 subsections, with 10 subject headings for philosophical articles along with two additional subsections for articles in cognitive (...) science and neuroscience. Of course the division is somewhat arbitrary, but I hope that it makes the bibliography easier to use. This bibliography has first been compiled by Thomas Metzinger and David Chalmers to appear in print in two philosophical anthologies on conscious experience . From 1995 onwards it has been continuously updated by Thomas Metzinger, and now is freely available as a PDF-, RTF-, or HTML-file. This bibliography mainly attempts to cover the Anglo-Saxon and German debates, in a non-annotated, fully formatted way that makes it easy to "cut and paste" from the original file. To a certain degree this bibliography also contains items in other languages than English and German - all submissions in other languages are welcome. Last update of current version: July 13th, 2001. (shrink)

This thesis has, as its primary target, the neo-cartesianism, or property dualism of certain philosophers of mind: David Chalmers, Tim Bayne, and others. All begin with a pre-theoretic commitment to the view that all perceptual states are conscious. They define consciousness by saying that it is synonymous with having ‘qualia’ – a term directed at phenomenal properties which defy reduction to physical states. The thesis argues that this position is challenged by certain neurological conditions, - blindsight, visual form agnosia etc- (...) which we can generalise as ‘dissociations’: conditions in which functions are separated from awareness. The thesis holds that these are examples of unconscious perception, which present the case for a different pre-theoretic position, and a redefinition of concepts used in the vicinity. Insofar as the neo-cartesians recognise the empirical, their inclination to reject the dissociations is challenged with new cases and paradigms which have emerged in recent years. It is contended that the dissociations disrupt Chalmers’ coherence between the phenomenal and the psychological, Bayne’s commitment to the Unity of Consciousness, and Phillips’ campaign against unconscious perception. In addition, synaesthesia is advanced as a problem case for Bayne’s unity contention. I argue that the dissociations are not easily dismissed, and present a real challenge for neo-cartesianism. In exploring this challenge, the thesis contributes to the case for a different philosophy of mind – a Higher Order Thought approach. The notion of unconscious perception – it is contended - much more easily finds an accommodation in HOT theories, so this thesis contributes to existing arguments for that position. HOT theories also have an advantage in being receptive to reduction, in giving a developmental account of consciousness, and in being more open to the accommodation of empirical discoveries. In each respect, there is an advantage over the respective positions taken by Chalmers and Bayne. (shrink)

The extent to which observed behavior in the complete commissurotomy patients is supported by only one hemisphere would depend on individual differences interacting with a variety of factors such as genetics, intelligence, and so on. The lesson imparted here is that there is sufficient functional redundancy in the neocortex so that the capacity to maintain a wide range of abilities is within the control of one hemisphere. And, yet, as seen in what is missing in the patients' behavior, one hemisphere (...) is not quite enough. Nature seems to have intended that the two hemispheres complement each other, that the full range of human behavior be best accomplished through interaction between the left and right hemispheres. (shrink)

The present review of literature surveys two main issues related to self-referential processes: (1) Where in the brain are these processes located, and do they correlate with brain areas uniquely specialized in self-processing? (2) What are the empirical and theoretical links between inner speech and self-awareness? Although initial neuroimaging attempts tended to favor a right hemispheric view of selfawareness, more recent work shows that the brain areas which support self-related processes are located in both hemispheres and are not uniquely activated (...) during self-reflective tasks. Furthermore, self-awareness at least partially relies on internal speech. An activation of Broca's area (which is known to sustain inner speech) is observed in a significant number of brain-imaging studies of self-reflection. Loss of inner speech following brain damage produces self-awareness deficits. Inner speech most likely can internally reproduce social mechanisms leading to self-awareness. Also, the process of self-reflection can be seen as being a problem-solving task, and self-talk as being a cognitive tool the individual uses to effectively work on the task. It is noted that although a large body of knowledge already exists on self-awareness, little is known about individual differences in dispositional self-focus and types of self-attention (e.g., rumination vs. self-reflection). (shrink)