|
1/15/05
*****PF Discussion: A Place for Consciousness*******
http://www.physicsforums.com/showthread.php?t=59766
|
CONSCIOUSNESS AND THE VOICES OF THE MIND
Few problems have had as interesting an intellectual trajectory through history as that of the mind and its place in nature. Before 1859, the year that Darwin and Wallace independently proposed natural selection as the basis of evolution, this issue was known as the mind/body problem with its various and sometimes ponderous solutions. But after that pivotal date, it came to be known as the problem of consciousness and its origin in evolution. Now the first thing I wish to stress this afternoon is this problem. It is easy for the average layman to understand. But paradoxically, for philosophers, psychologists, and neurophysiologists, who have been so used to a different kind of thinking, it is a difficult thing. What we have to explain is the contrast, so obvious to a child, between all the inner covert world of imaginings and memories and thoughts and the external public world around us. The theory of evolution beautifully explains the anatomy of species, but how out of mere matter, mere molecules, mutations, anatomies, can you get this rich inner experience that is always accompanying us during the day and in our dreams at night? That is the problem we will consider in this symposium. [continued]
|
http://www.julianjaynes.org/pdf/jaynes_mind.pdf
PF Thread: http://www.physicsforums.com/showthread.php?t=58745
|
ON A CONFUSION ABOUT A FUNCTION OF CONSCIOUSNESS
Consciousness is a mongrel concept: there are a number of very different "consciousnesses." Phenomenal consciousness is experience; the phenomenally conscious aspect of a state is what it is like to be in that state. The mark of access-consciousness, by contrast, is availability for use in reasoning and rationally guiding speech and action. These concepts are often partly or totally conflated, with bad results. This target article uses as an example a form of reasoning about a function of "consciousness" based on the phenomenon of blindsight. Some information about stimuli in the blind field is represented in the brains of blindsight patients, as shown by their correct "guesses," but they cannot harness this information in the service of action, and this is said to show that a function of phenomenal consciousness is somehow to enable information represented in the brain to guide action. But stimuli in the blind field are BOTH access-unconscious and phenomenally unconscious. The fallacy is: an obvious function of the machinery of access-consciousness is illicitly transferred to phenomenal consciousness.
|
http://www.bbsonline.org/Preprints/O...bbs.block.html
|
Facing Up to the Problem of Consciousness
Consciousness poses the most baffling problems in the science of the mind. There is nothing that we know more intimately than conscious experience, but there is nothing that is harder to explain. All sorts of mental phenomena have yielded to scientific investigation in recent years, but consciousness has stubbornly resisted. Many have tried to explain it, but the explanations always seem to fall short of the target. Some have been led to suppose that the problem is intractable, and that no good explanation can be given.
To make progress on the problem of consciousness, we have to confront it directly. In this paper, I first isolate the truly hard part of the problem, separating it from more tractable parts and giving an account of why it is so difficult to explain. I critique some recent work that uses reductive methods to address consciousness, and argue that such methods inevitably fail to come to grips with the hardest part of the problem. Once this failure is recognized, the door to further progress is opened. In the second half of the paper, I argue that if we move to a new kind of nonreductive explanation, a naturalistic account of consciousness can be given. I put forward my own candidate for such an account: a nonreductive theory based on principles of structural coherence and organizational invariance and a double-aspect view of information. [continued]
|
http://jamaica.u.arizona.edu/~chalme...rs/facing.html
|
Consciousness and Complexity
Conventional approaches to understanding consciousness are generally concerned with the contribution of speciÞc brain areas or groups of neurons. By contrast, it is considered here what kinds of neural processes can account for key properties of conscious experience. Applying measures of neural integration and complexity, together with an analysis of extensive neurological data, leads to a testable proposalÑthe dynamic core hypothesisÑabout the properties of the neural substrate of consciousness.
|
http://scholar.google.com/url?q=http.../tononi282.pdf
|
Consciousness: The Remembered Present
This chapter summarizes a theory of consciousness based on brain structure and dynamics. The theory centers around the notion of reentry—ongoing recursive signaling across multiple reciprocally connected brain regions present mainly in the thalamocortical system. It recognized the fundamental beginnings provided by the complementary efforts of Ramon y Cajal and William James.[continued]
|
http://www.annalsnyas.org/cgi/conten...ract/929/1/111
|
A sensorimotor account of vision and visual onsciousness
Abstract: Many current neurophysiological, psychophysical, and psychological approaches to vision rest on the idea that when we see, the brain produces an internal representation of the world. The activation of this internal representation is assumed to give rise to the experience of seeing. The problem with this kind of approach is that it leaves unexplained how the existence of such a detailed internal representation might produce visual consciousness. An alternative proposal is made here. We propose that seeing is a way of acting. It is a particular way of exploring the environment. Activity in internal representations does not generate the experience of seeing. The outside world serves as its own, external, representation. The experience of seeing occurs when the organism masters what we call the governing laws of sensorimotor contingency. The advantage of this approach is that it provides a natural and principled way of accounting for visual consciousness, and for the differences in the perceived quality of sensory experience in the different sensory modalities. Several lines of empirical evidence are brought forward in support of the theory, in particular: evidence from experiments in sensorimotor adaptation, visual “filling in,” visual stability despite eye movements, change blindness, sensory substitution, and color perception. [continued]
|
http://scholar.google.com/url?q=http...40525X01410119
|
Toward a theory of episodic memory: The frontal lobes and autonoetic consciousness.
Adult humans are capable of remembering prior events by mentally traveling back in time to reexperience those events. In this review, the authors discuss this and other related capabilities. considering evidence from such diverse sources as brain imaging, neuropsychological experiments, clinical observations, and developmental psychology. The evidence supports a preliminary theory of episodic remembering, which holds that the prefrontal cortex plays a critical, supervisory role in empowering healthy adults with autonoetic consciousness--the capacity to mentally represent and become aware of subjective experiences in the past, present, and future. When a rememberer mentally travels back in subjective time to reexperience his or her personal past, the result is an act of retrieval from episodic memory. (PsycINFO Database Record (c) 2004 APA, all rights reserved)
|
http://content.apa.org/journals/bul/121/3/331
|
the mechanisms of consciousness
A number of recent papers and books discuss theoretical efforts toward a scientific understanding of consciousness. Progress in imaging networks of brain areas active when people perform simple tasks may provide a useful empirical background for distinguishing conscious and unconscious information processing. Attentional networks include those involved in orienting to sensory stimuli, activating ideas from memory, and maintaining the alert state. This paper reviews recent findings in relation to classical issues in the study of attention and anatomical and physical theories of the nature of consciousness. [continued]
|
http://www.pubmedcentral.nih.gov/art...gi?artid=44408
|
Temporal binding, binocular rivalry, and consciousness.
Cognitive functions like perception, memory, language, or consciousness are based on highly parallel and distributed information processing by the brain. One of the major unresolved questions is how information can be integrated and how coherent representational states can be established in the distributed neuronal systems subserving these functions. It has been suggested that this so-called "binding problem" may be solved in the temporal domain. The hypothesis is that synchronization of neuronal discharges can serve for the integration of distributed neurons into cell assemblies and that this process may underlie the selection of perceptually and behaviorally relevant information. As we intend to show here, this temporal binding hypothesis has implications for the search of the neural correlate of consciousness. We review experimental results, mainly obtained in the visual system, which support the notion of temporal binding. In particular, we discuss recent experiments on the neural mechanisms of binocular rivalry which suggest that appropriate synchronization among cortical neurons may be one of the necessary conditions for the buildup of perceptual states and awareness of sensory stimuli. Copyright 1999 Academic Press. [continued]
|
http://www.ncbi.nlm.nih.gov/entrez/q...&dopt=Citation
|
Attention, self regulation and consciousness
Consciousness has many aspects. These include awareness of the world, feelings of control over one's behaviour and mental state (volition), and the notion of a continuing self. Focal (executive) attention is used to control details of our awareness and is thus closely related to volition. Experiments suggest an integrated network of neural areas involved in executive attention. This network is associated with our voluntary ability to select among competing items, to correct error and to regulate our emotions. Recent neuroimaging studies suggest that these various functions involve separate areas of the anterior cingulate. We have adopted a strategy of using marker tasks, shown to activate the brain area by imaging studies, as a means of tracing the development of attentional networks. Executive attention appears to develop first to regulate distress during the first year of life. During later childhood the ability to regulate conflict among competing stimuli builds upon the earlier cingulate anatomy to provide a means of cognitive control. During childhood the activation of cingulate structures relates both to the child's success on laboratory tasks involving conflict and to parental reports of self-regulation and emotional control. These studies indicate a start in understanding the anatomy, circuitry and development of executive attention networks that serve to regulate both cognition and emotion. [continued]
|
http://www.journals.royalsoc.ac.uk/a...lts,1:102022,1
|
Beyond consciousness of external reality: a "who" system for consciousness of action and self-consciousness.
This paper offers a framework for consciousness of internal reality. Recent PET experiments are reviewed, showing partial overlap of cortical activation during self-produced actions and actions observed from other people. This overlap suggests that representations for actions may be shared by several individuals, a situation which creates a potential problem for correctly attributing an action to its agent. The neural conditions for correct agency judgments are thus assigned a key role in self/other distinction and self-consciousness. A series of behavioral experiments that demonstrate, in normal subjects, the poor monitoring of action-related signals and the difficulty in recognizing self-produced actions are described. In patients presenting delusions, this difficulty dramatically increases and actions become systematically misattributed. These results point to schizophrenia and related disorders as a paradigmatic alteration of a "Who?" system for self-consciousness. Copyright 1998 Academic Press. [continued]
|
http://www.ncbi.nlm.nih.gov/entrez/q...&dopt=Citation
|
The neuronal basis for consciousness
Attempting to understand how the brain, as a whole, might be organized seems, for the first time, to be a serious topic of inquiry. One aspect of its neuronal organization that seems particularly central to global function is the rich thalamocortical interconnectivity, and most particularly the reciprocal nature of the thalamocortical neuronal loop function. Moreover, the interaction between the specific and non-specific thalamic loops suggests that rather than a gate into the brain, the thalamus represents a hub from which any site in the cortex can communicate with any other such site or sites. The goal of this paper is to explore the basic assumption that large-scale, temporal coincidence of specific and non-specific thalamic activity generates the functional states that characterize human cognition.[continued]
|
http://scholar.google.com/url?q=http...lTran_1998.pdf
|
Are we explaining consciousness yet?
Theorists are converging from quite different quarters on a version of the global neuronal workspace model of consciousness, but there are residual confusions to be dissolved. In particular, theorists must resist the temptation to see global accessibility as the cause of consciousness (as if consciousness were some other, further condition); rather, it is consciousness. A useful metaphor for keeping this elusive idea in focus is that consciousness is rather like fame in the brain. It is not a privileged medium of representation, or an added property some states have; it is the very mutual accessibility that gives some informational states the powers that come with a subject's consciousness of that information. Like fame, consciousness is not a momentary condition, or a purely dispositional state, but rather a matter of actual influence over time. Theorists who take on the task of accounting for the aftermath that is critical for consciousness often appear to be leaving out the Subject of consciousness, when in fact they are providing an analysis of the Subject, a necessary component in any serious theory of consciousness[continued]
|
http://www.ncbi.nlm.nih.gov/entrez/q...&dopt=Citation
|
Towards a cognitive neuroscience of consciousness: basic evidence and a workspace framework
This introductory chapter attempts to clarify the philosophical, empirical, and theoretical bases on which a cognitive neuroscience approach to consciousness can be founded. We isolate three major empirical observations that any theory of consciousness should incorporate, namely (1) a considerable amount of processing is possible without consciousness, (2)
attention is a prerequisite of consciousness, and (3) consciousness is required for some specifc cognitive tasks, including those that require durable information maintenance, novel combinations of operations, or the spontaneous generation of intentional behavior. We then propose a theoretical framework that synthesizes those facts: the hypothesis of a global neuronal workspace. [continued]
|
http://scholar.google.com/url?q=http...nition2001.pdf
|
The Link between Brain Learning, Attention, and Consciousness
The processes whereby our brains continue to learn about a changing world in a stable fashion throughout life are proposed to lead to conscious experiences. These processes include the learning of top-down expectations, the matching of these expectations against bottom-up data, the focusing of attention upon the expected clusters of information, and the development of resonant states between bottom-up and top-down processes as they
reach an attentive consensus between what is expected and what is there in the outside world. It is suggested that all conscious states in the brain are resonant states and that these resonant states trigger learning of sensory and cognitive representations. The models which summarize these concepts are therefore called Adaptive Resonance Theory, or ART, models. Psychophysical and neurobiological data in support of ART are presented from
early vision, visual object recognition, auditory streaming, variable-rate speech perception, somatosensory perception, and cognitive–emotional interactions, among others. It is noted that ART mechanisms seem to be operative at all levels of the visual system, and it is proposed how these mechanisms are realized by known laminar circuits of visual cortex. It is predicted that the same circuit realization of ART mechanisms will be found in the laminar circuits of all sensory and cognitive neocortex. Concepts and data are summarized concerning how some visual percepts may be visibly, or modally, perceived, whereas amodal percepts may be consciously recognized even though they are perceptually invisible. It is also suggested that sensory and cognitive processing in the What processing stream of the brain obey top-down matching and learning laws that are often complementary to
those used for spatial and motor processing in the brain’s Where processing stream. This enables our sensory and cognitive representations to maintain their stability as we learn more about the world, while allowing spatial and motor representations to forget learned maps and gains that are no longer appropriate as our bodies develop and grow from infanthood to adulthood. Procedural memories are proposed to be unconscious because the inhibitory matching process that supports these spatial and motor processes cannot lead to resonance. ã 1999 Academic Press [continued]
|
http://scholar.google.com/url?q=http...onscCogn99.pdf
|