Consciousness seems to be an enigmatic phenomenon: it is difficult to imagine how our perceptions of the world and our inner thoughts, sensations and feelings could be related to the immensely complicated biological organ we call the brain. This volume presents the thoughts of some of the leading philosophers and cognitive scientists who have recently participated in the discussion of the status of consciousness in science. The focus of inquiry is the question: "Is it possible to incorporate consciousness into science?" (...) Philosophers have suggested different alternatives -- some think that consciousness should be altogether eliminated from science because it is not a real phenomenon, others that consciousness is a real, higher-level physical or neurobiological phenomenon, and still others that consciousness is fundamentally mysterious and beyond the reach of science. At the same time, however, several models or theories of the role of conscious processing in the brain have been developed in the more empirical cognitive sciences. It has been suggested that non-conscious processes must be sharply separated from conscious ones, and that the necessity of this distinction is manifested in the curious behavior of certain brain-damaged patients. This book demonstrates the dialogue between philosophical and empirical points of view. The writers present alternative solutions to the brain-consciousness problem and they discuss how the unification of biological and psychological sciences could thus become feasible. Covering a large ground, this book shows how the philosophical and empirical problems are closely interconnected. From this interdisciplinary exploration emerges the conviction that consciousness can and should be a natural part of our scientific world view. (shrink)
Several theories claim that dreaming is a random by-product of REM sleep physiology and that it does not serve any natural function. Phenomenal dream content, however, is not as disorganized as such views imply. The form and content of dreams is not random but organized and selective: during dreaming, the brain constructs a complex model of the world in which certain types of elements, when compared to waking life, are underrepresented whereas others are over represented. Furthermore, dream content is consistently (...) and powerfully modulated by certain types of waking experiences. On the basis of this evidence, I put forward the hypothesis that the biological function of dreaming is to simulate threatening events, and to rehearse threat perception and threat avoidance. To evaluate this hypothesis, we need to consider the original evolutionary context of dreaming and the possible traces it has left in the dream content of the present human population. In the ancestral environment human life was short and full of threats. Any behavioral advantage in dealing with highly dangerous events would have increased the probability of reproductive success. A dream-production mechanism that tends to select threatening waking events and simulate them over and over again in various combinations would have been valuable for the development and maintenance of threat-avoidance skills. Empirical evidence from normative dream content, children's dreams, recurrent dreams, nightmares, post traumatic dreams, and the dreams of hunter-gatherers indicates that our dream-production mechanisms are in fact specialized in the simulation of threatening events, and thus provides support to the threat simulation hypothesis of the function of dreaming. Key Words: dream content; dream function; evolution of consciousness; evolutionary psychology; fear; implicit learning; nightmares; rehearsal; REM; sleep; threat perception. (shrink)
In this paper I develop the thesis that dreams are essential to an understanding of waking consciousness. In the first part I argue in opposition to the philosophers Malcolm and Dennett that empirical evidence now shows dreams to be real conscious experiences. In the second part, three questions concerning consciousness research are addressed. (1) How do we isolate the system to be explained (consciousness) from other systems? (2) How do we describe the system thus isolated? (3) How do we reveal (...) the mechanisms on which this system is based? I suggest that empirical dream research combined with other empirical approaches can help us to sketch answers to all of these questions. I argue that the subjective form of dreams reveals the subjective, macro-level form of consciousness in general and that both dreams and the everyday phenomenal world may be thought of as constructed “virtual realities”. A major task for empirical consciousness research is to find out the mechanisms which bind this experienced world into a coherent whole. (shrink)
Event-related potential studies have attempted to discover the processes that underlie conscious visual perception by contrasting ERPs produced by stimuli that are consciously perceived with those that are not. Variability of the proposed ERP correlates of consciousness is considerable: the earliest proposed ERP correlate of consciousness coincides with sensory processes and the last one marks postperceptual processes. A negative difference wave called visual awareness negativity , typically observed around 200 ms after stimulus onset in occipitotemporal sites, gains strong support for (...) reflecting the processes that correlate with, and possibly enable, aware visual perception. Research suggests that the early parts of conscious processing can proceed independently of top-down attention, although top-down attention may modulate visual processing even before consciousness. Evidence implies that the contents of consciousness are provided by interactions in the ventral stream, but indispensable contributions from dorsal regions influence already low-level visual responses. (shrink)
The cognitive mind-brain is haunted by the ghost of consciousness. Cognitive science must face this ghost, since consciousness is perhaps the most important mental phenomenon: it forms a seemingly united, multimodal phenomenological world around the subject who experiences this world from a certain point of view. Many current approaches to consciousness fail to illuminate the nature of this “experienced world”. Some philosophers want to eliminate consciousness from science for good, others build theories in which the concept of consciousness is distorted (...) beyond recognition. I argue that elimination and Daniel Dennett's “multiple drafts” model do not offer genuine explanations for consciousness. However, certain empirically-based approaches to consciousness succeed in exorcising its ghostly reputation and, at the same time, in preserving the experienced world of consciousness as an important explanandum. (shrink)
The binding problem is frequently discussed in consciousness research. However, it is by no means clear what the problem is supposed to be and how exactly it relates to consciousness. In the present paper the nature of the binding problem is clarified by distinguishing between different formulations of the problem. Some of them make no mention of consciousness, whereas others are directly related to aspects of phenomenal experience. Certain formulations of the binding problem are closely connected to the classical philosophical (...) problem of the unity of consciousness and the currently fashionable search for the neural correlates of consciousness. Nonetheless, only a part of the current empirical research on binding is directly relevant to the study of consciousness. The main message of the present paper is that the science of consciousness needs to establish a clear theoretical view of the relation between binding and consciousness and to encourage further empirical work that builds on such a theoretical foundation. (shrink)
The threat simulation theory of dreaming states that dream consciousness is essentially an ancient biological defence mechanism, evolutionarily selected for its capacity to repeatedly simulate threatening events. Threat simulation during dreaming rehearses the cognitive mechanisms required for efficient threat perception and threat avoidance, leading to increased probability of reproductive success during human evolution. One hypothesis drawn from TST is that real threatening events encountered by the individual during wakefulness should lead to an increased activation of the system, a threat simulation (...) response, and therefore, to an increased frequency and severity of threatening events in dreams. Consequently, children who live in an environment in which their physical and psychological well-being is constantly threatened should have a highly activated dream production and threat simulation system, whereas children living in a safe environment that is relatively free of such threat cues should have a weakly activated system. We tested this hypothesis by analysing the content of dream reports from severely traumatized and less traumatized Kurdish children and ordinary, non-traumatized Finnish children. Our results give support for most of the predictions drawn from TST. The severely traumatized children reported a significantly greater number of dreams and their dreams included a higher number of threatening dream events. The dream threats of traumatized children were also more severe in nature than the threats of less traumatized or non-traumatized children. (shrink)
We tested the new threat simulation theory of the biological function of dreaming by analysing 592 dreams from 52 subjects with a rating scale developed for quantifying threatening events in dreams. The main predictions were that dreams contain more frequent and more severe threats than waking life does; that dream threats are realistic; and that they primarily threaten the Dream Self who tends to behave in a relevant defensive manner in response to them. These predictions were confirmed and the theory (...) empirically supported. We suggest that the threat simulation theory of dreaming may have wider implications for theories about the function of consciousness. (shrink)
We investigated whether inconsistencies in previous studies regarding emotional experiences in dreams derive from whether dream emotions are self-rated or externally evaluated. Seventeen subjects were monitored with polysomnography in the sleep laboratory and awakened from every rapid eye movement sleep stage 5 min after the onset of the stage. Upon awakening, participants gave an oral dream report and rated their dream emotions using the modified Differential Emotions Scale, whereas external judges rated the participants’ emotions expressed in the dream reports, using (...) the same scale. The two approaches produced diverging results. Self-ratings, as compared to external ratings, resulted in greater estimates of emotional dreams; positively valenced dreams; positive and negative emotions per dream; and various discrete emotions represented in dreams. The results suggest that this is mostly due to the underrepresentation of positive emotions in dream reports. Possible reasons for this discrepancy are discussed. (shrink)
The philosophical foundations of consciousness science -- The historical foundations of consciousness science -- The conceptual foundations of consciousness science -- Neuropsychological deficits of visual consciousness -- Neuropsychological dissociations of visual consciousness from behaviour -- Neuropsychological disorders of self-awareness -- Methods and design of NCC experiments -- Studies on the neural basis of consciousness as a state -- Studies on the neural basis of visual consciousness.
To study whether the distinction between introspective and non-introspective states of mind is an empirical reality or merely a conceptual distinction, we measured event-related potentials elicited in introspective and non-introspective instruction conditions while the observers were trying to detect the presence of a masked stimulus. The ERPs indicated measurable differences related to introspection in both preconscious and conscious processes. Our data support the hypothesis that introspective states empirically differ from non-introspective states.
Binding can be described at three different levels: In neuroscience it refers to the integration of single-cell activities to form functional neural assemblies, especially in response to global stimulus properties; in cognitive science it refers to the integration of distributed modular input processing to form unified representations for memory and action, and in consciousness studies it refers to the unity of phenomenal consciousness . To describe and explain the unity of consciousness, detailed phenomenological descriptions of binding at the phenomenal level (...) and clarification of the underlying cognitive and neural mechanisms are required. The disunity of consciousness during dreaming is a fruitful avenue to study phenomenal binding and its mechanisms. The notion of the 'bizarreness' of dreams is closely related to the concept of 'binding': bizarreness can be reconceptualized as referring to different types of unusual combinations of features in the binding of dream images coherently together. The present study concentrates on the representation of human characters and the bizarreness found in these representations. We developed a rating scale that distinguishes different types of bizarreness on the basis of the unusual combinations of elements that are manifested in dream images. The data consisted of 592 dream reports in the home-based dream diaries of 52 students. The results indicate that about half of the human characters appearing in our dreams contain bizarre elements, and that certain types of bizarreness are more frequent than others. Phenomenal features intrinsic to the representation of a person are less frequently bizarre than is the external relation between the person and the context . Thus, binding the local features of a representation coherently together appears to be less prone to errors than binding several different information streams together into a coherent phenomenal model of the world. (shrink)
Malcolm-Smith, Solms, Turnbull and Tredoux [Malcolm-Smith, S., Solms, M.,Turnbull, O., & Tredoux, C. . Threat in dreams: An adaptation? Consciousness and Cognition, 17, 1281–1291.] have made an attempt to test the Threat-Simulation Theory , a theory offering an evolutionary psychological explanation for the function of dreaming [Revonsuo, A. . The reinterpretation of dreams: An evolutionary hypothesis of the function of dreaming. Behavioral and Brain Sciences, 23, 877–901]. Malcolm-Smith et al. argue that empirical evidence from their own study as well as (...) from some other studies in the literature does not support the main predictions of the TST: that threatening events are frequent and overrepresented in dreams, that exposure to real threats activates the threat-simulation system, and that dream threats contain realistic rehearsals of threat avoidance responses. Other studies, including our own, have come up with results and conclusions that are in conflict with those of Malcolm-Smith et al. In this commentary, we provide an analysis of the sources of these disagreements, and their implications to the TST. Much of the disagreement seems to stem from differing interpretations of the theory and, consequently, of differing methods to test it. (shrink)
The most challenging objections to the Threat Simulation Theory (TST) of the function of dreaming include such issues as whether the competing Random Activation Theory can explain dreaming, whether TST can accommodate the apparently dysfunctional nature of post-traumatic nightmares, whether dreams are too bizarre and disorganized to constitute proper simulations, and whether dream recall is too biased to reveal the true nature of dreams. I show how these and many other objections can be accommodated by TST, and how several lines (...) of new supporting evidence are provided by the commentators. Accordingly TST offers a promising new approach to the function of dreaming, covering a wide range of evidence and theoretically integrating psychological and biological levels of explanation. (shrink)
“Altered State of Consciousness” (ASC) has been defined as a changed overall pattern of conscious experience, or as the subjective feeling and explicit recognition that one's own subjective experience has changed. We argue that these traditional definitions fail to draw a clear line between altered and normal states of consciousness (NSC). We outline a new definition of ASC and argue that the proper way to understand the concept of ASC is to regard it as a representational notion: the alteration that (...) has happened is not an alteration of consciousness (or subjective experience) per se, but an alteration in the informational or representational relationships between consciousness and the world. An altered state of consciousness is defined as a state in which the neurocognitive background mechanisms of consciousness have an increased tendency to produce misrepresentations such as hallucinations, delusions, and memory distortions. Paradigm examples of such generally misrepresentational, temporary, and reversible states are dreaming, psychotic episodes, psychedelic drug experiences, some epileptic seizures, and hypnosis in highly hypnotizable subjects. The representational definition of ASC should be applied in the theoretical and empirical studies of ASCs to unify and clarify the conceptual basis of ASC research. (shrink)
If we assume that consciousness is a natural biological phenomenon in the brain, should we expect the current brain sensing and imaging methods to somehow ‘discover’ consciousness? The answer depends on the following points: What kind of level of biological organization do we assume consciousness to be? What would count as the discovery of this level? What are the levels of organization from which the currently available research instruments pick signals and acquire data? Single-cell recordings, PET, fMRI, EEG and MEG (...) pick different types of signals from different levels of organization in the brain. However, it seems they do not manage to pick signals that would allow the direct visualization and reconstruction of the higher levels of electrophysiological organization that are crucial for the empirical discovery and theoretical explanation of consciousness. The message of the present paper is twofold: On the one hand, we should be aware of the practical limitations of the currently available methods of cognitive neuroscience and not read too much into the images produced by them. On the other hand, the present limitations could be overcome by more sophisticated methods in the future. Therefore, contrary to what several philosophers have argued, the empirical discovery of consciousness in the brain is not impossible in principle. (shrink)
Cognitive functions associated with the frontal lobes of the brain may be specifi cally involved in hypnosis. Thus, the frontal area of the brain has recently been of great interest when searching for neural changes associated with hypnosis. We tested the hypothesis that EEG during pure hypnosis would differ from the normal non-hypnotic EEG especially above the frontal area of the brain. The composition of brain oscillations was examined in a broad frequency band (130 Hz) in the electroencephalogram (EEG) of (...) a single virtuoso subject. Data was collected in two independent data collection periods separated by one year. The hypnotic and non-hypnotic conditions were repeated multiple times during each data acquisition session. We found that pure hypnosis induced reorganization in the composition of brain oscillations especially in prefrontal and right occipital EEG channels. Additionally, hypnosis was characterized by consistent rightside-dominance asymmetry. In the prefrontal EEG channels the composition of brain oscillations included spectral patterns during hypnosis that were completely different from those observed during non-hypnosis. Furthermore, the EEG spectral patterns observed overall during the hypnotic condition did not return to the pre-hypnotic baseline EEG immediately when hypnosis was terminated. This suggests that for the brain, the return to a normal neurophysiological baseline condition after hypnosis is a time-consuming process. The present results suggest that pure hypnosis is characterized by an increase in alertness and heightened attention, refl ected as cognitive and neuronal activation. Taken together, the present data provide support for the hypothesis that in a very highly hypnotizable person (a hypnotic virtuoso) hypnosis as such may be accompanied by a changed pattern of neural activity in the brain. (shrink)
Pessoa et al. fail to make a clear distinction between visual perception and subjective visual awareness. Their most controversial claims, however, concern subjective visual awareness rather than visual perception: visual awareness is externalized to the “personal level,” thus denying the view that consciousness is a natural biological phenomenon somehow constructed inside the brain.
The research program defended by O'Regan & Noë (O&N) cannot give any plausible explanation for the fact that during REM-sleep the brain regularly generates subjective experiences (dreams) where visual phenomenology is especially prominent. This internal experience is almost invariably organized in the form of “being-in-the-world.” Dreaming presents a serious unaccountable anomaly for the sensorimotor research program and reveals that some of its fundamental assumptions about the nature of consciousness are questionable.
Cortex functional connectivity associated with hypnosis was investigated in a single highly hypnotizable subject in a normal baseline condition and under neutral hypnosis during two sessions separated by a year. After the hypnotic induction, but without further suggestions as compared to the baseline condition, all studied parameters of local and remote functional connectivity were significantly changed. The significant differences between hypnosis and the baseline condition were observable (to different extent) in five studied independent frequency bands (delta, theta, alpha, beta, and (...) gamma). The results were consistent and stable after 1 year. Based on these findings we conclude that alteration in functional connectivity of the brain may be regarded as a neuronal correlate of hypnosis (at least in very highly hypnotizable subjects) in which separate cognitive modules and subsystems may be temporarily incapable of communicating with each other normally. (shrink)
The approach of Hobson et al. is limited to the description of global states of consciousness, although more detailed analyses of the specific contents of consciousness would also be required. Furthermore, their account of the mind-brain relationship remains obscure. Nielsen's discussion suffers from conceptual and definitional unclarity. Mentation during sleep could be clarified by reconceptualizing it as an issue about the contents of consciousness. Vertes & Eastman do not consider the types of memory (emotional) and learning (implicit) that are relevant (...) during REM sleep, and therefore dismiss on inadequate grounds the possibility of memory functions associated with REM sleep. [Hobson et al.; Nielsen; Vertes & Eastman]. (shrink)
I disagree with Ross about the location of colors: They are in the brain, not in the external world. It is difficult to deny that there are colors in our conscious visual experience, and if we take the causal theory of perception seriously, we cannot identify these colors with the beginning of the causal chain in perception (external objects in the distal stimulus field), but we must search for them at the end of the causal chain (in the brain). Several (...) lines of compelling evidence from cognitive neuroscience (e.g., synesthesia, dreaming, and achromatopsia) demonstrate unambiguously that color is in the brain. Furthermore, it seems that Ross has failed to consider one substantial version of subjectivism in his article. This monistic approach to color and consciousness appears to be the least implausible alternative when we try to understand what colors are and where they reside. (shrink)
commentary on Dainton, B. (2000). Stream of Consciousness: Unity and Continuity in Conscious Experience. London: Routledge. ABSTRACT: Stream of Consciousness is a detailed and insightful analysis of the nature of phenomenal consciousness, especially its unity at a time and continuity over stretches of time. I find Dainton's approach to phenomenal consciousness in many ways sound but I also point out one major source of disgreement between us. Dainton believes that to explain phenomenal unity and continuity, no reference to anything outside (...) experience is required. Thus, he postulates a fundamental experiential relation called co-consciousness which is supposed to do all the explanatory work. On the contrary, I hold that to truly explain features of consciousness such as phenomenal unity and continuity, reference to mechanisms outside the phenomenal realm are necessary. (shrink)
The empirical exploration of the neural mechanisms of consciousness is undoubtedly going to be one of the most central lines of research in the scientific study of consciousness. Therefore, it is important for the researchers involved in these studies to have a clear idea of the phenomenon they are searching for and of the capabilities of the methods they are using to accomplish the task. The main point of my paper ‘Can functional brain imaging discover consciousness in the brain?’ was (...) to explicate and clarify these issues that, although central metatheoretical problems for cognitive neuroscience, have not received much attention from either the experimental neuroscientists or the philosophers involved in the study of consciousness. (shrink)
The Gestalt Bubble model of visual consciousness is a courageous attempt to take the first-person perspective as primary in the study of consciousness. I have developed similar ideas as the Virtual Reality Metaphor of consciousness (Revonsuo 1995; 2000). I can, hence, only agree with Lehar about the general shape of a proper research strategy for the study of consciousness. As to the metaphysical basis of the research program, I have, however, several reservations about panexperientialism.
Explanatory problems in the philosophy of neuroscience are not well captured by the division between the radical and the trivial neuron doctrines. The actual problem is, instead, whether mechanistic biological explanations across different levels of description can be extended to account for psychological phenomena. According to cognitive neuroscience, some neural levels of description at least are essential for the explanation of psychological phenomena, whereas, in traditional cognitive science, psychological explanations are completely independent of the neural levels of description. The challenge (...) for cognitive neuroscience is to discover the levels of description appropriate for the neural explanation of psychological phenomena. (shrink)