A theory of consciousness

Consciousness is the subjective awareness of momentary experience interpreted in the context of personal memory and present state. I propose that two brain systems converge to create consciousness. The exogenous system sends information about multimodal external stimuli to basal dendrites in widely dispersed pyramidal cell ensembles in the cortex of the brain; this system produces synchronized fragments of sensations. The endogenous system distributes readout of representations of memories, activated in systems established by associative learning, diffusely to apical dendrites. Convergence of exogenous and endogenous inputs enhances cellular excitability, and fragmented sensations are thereby converted to fragments of perception. Local field potentials periodically modulate all cortical membrane potentials and facilitate synchronous discharge of these excited elements. Feedback between the cortex and the thalamus results in a cortico-thalamo-cortical reverberation, binding the fragments into a unified global percept. Sustained reverberation produces a resonating electromagnetic field of synchronized elements. The momentary content of information in the brain is this distributed coherence, which is negative entropy. Consciousness is a physical property of this field, producing the subjective awareness of this information.     

Toward a theory of visual consciousness.

The visual brain consists of several parallel, functionally specialized processing systems, each having several stages (nodes) which terminate their tasks at different times; consequently, simultaneously presented attributes are perceived at the same time if processed at the same node and at different times if processed by different nodes. Clinical evidence shows that these processing systems can act fairly autonomously. Damage restricted to one system compromises specifically the perception of the attribute that that system is specialized for; damage to a given node of a processing system that leaves earlier nodes intact results in a degraded perceptual capacity for the relevant attribute, which is directly related to the physiological capacities of the cells left intact by the damage. By contrast, a system that is spared when all others are damaged can function more or less normally. Moreover, internally created visual percepts-illusions, afterimages, imagery, and hallucinations-activate specifically the nodes specialized for the attribute perceived. Finally, anatomical evidence shows that there is no final integrator station in the brain, one which receives input from all visual areas; instead, each node has multiple outputs and no node is recipient only. Taken together, the above evidence leads us to propose that each node of a processing-perceptual system creates its own microconsciousness. We propose that, if any binding occurs to give us our integrated image of the visual world, it must be a binding between microconsciousnesses generated at different nodes. Since any two microconsciousnesses generated at any two nodes can be bound together, perceptual integration is not hierarchical, but parallel and postconscious. By contrast, the neural machinery conferring properties on those cells whose activity has a conscious correlate is hierarchical, and we refer to it as generative binding, to distinguish it from the binding that might occur between the microconsciousnesses.     

The many-worlds theory of consciousness

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.     

A software agent model of consciousness.

Baars (1988, 1997) has proposed a psychological theory of consciousness, called global workspace theory. The present study describes a software agent implementation of that theory, called "Conscious" Mattie (CMattie). CMattie operates in a clerical domain from within a UNIX operating system, sending messages and interpreting messages in natural language that organize seminars at a university. CMattie fleshes out global workspace theory with a detailed computational model that integrates contemporary architectures in cognitive science and artificial intelligence. Baars (1997) lists the psychological "facts that any complete theory of consciousness must explain" in his appendix to In the Theater of Consciousness; global workspace theory was designed to explain these "facts." The present article discusses how the design of CMattie accounts for these facts and thereby the extent to which it implements global workspace theory.     

Indirect representation and the self-representational theory of consciousness

According to Uriah Kriegel’s self-representational theory of consciousness, mental state M is conscious just in case it is a complex with suitably integrated proper parts, M ₁ and M ₂, such that M ₁ is a higher-order representation of lower-order representation M ₂. Kriegel claims that M thereby “indirectly” represents itself, and he attempts to motivate this claim by appealing to what he regards as intuitive cases of indirect perceptual and pictorial representation. For example, Kriegel claims that it’s natural to say that in directly perceiving the front surface of an apple one thereby perceives the apple itself. Cases such as this are supposed to provide intuitive support for the principle that if X represents Y, and Y is highly integrated into complex object Z, then X indirectly represents Z. In this paper I provide counterexamples to Kriegel’s principle of indirect representation, before going on to argue that we can explain what is going on in those cases in which the subject seems to represent a complex whole by representing one its parts without positing indirect representations anyway. I then argue that my alternative approach is superior to Kriegel’s in a number of ways, thereby rendering his theory of consciousness implausible.     

A strong developmental theory of field dependence-independence

Assume an X-linked gene in two alleles mediates performance on field dependent-independent tests such as the rod-and-frame test. Only the recessive gene with relative frequency q facilitates field independence. Other genotypes lead to field dependence. Under a simple genetic model, field dependence-independence may be viewed as outcomes of a discrete random variable B with field independent and dependent probabilities π_iq and 1 ? π_iq for men, and π_iq² and 1 ? π_iq² for women, respectively. The parameter π_i is a maturational ageindexed parameter, 0 < π_i ≤ 1, monotonically increasing with development until maturity when π_k = 1. Observations of performance are made on a random variable W of the form W = B + N, where N is normal in distribution independent of B; N represents a composite of influences including error. The model implies testable age-related between- and within-sex predictions regarding E(W) and Var(W), predictions which appear to coincide with major empirical findings; it also generates novel predictions. For instance, W is a mixture of normals distribution. The model is briefly evaluates in two data sets.     

The nature of primary consciousness. A new synthesis

While the philosophical puzzles about “life” that once confounded biology have all been solved by science, much of the “mystery of consciousness” remains unsolved due to multiple “explanatory gaps” between the brain and conscious experience. One reason for this impasse is that diverse brain architectures both within and across species can create consciousness, thus making any single neurobiological feature insufficient to explain it. We propose instead that an array of general biological features that are found in all living things, combined with a suite of special neurobiological features unique to animals with consciousness, evolved to create subjective experience. Combining philosophical, neurobiological and evolutionary approaches to consciousness, we review our theory of neurobiological naturalism that we argue closes the “explanatory gaps” between the brain and subjective experience and naturalizes the “experiential gaps” between subjectivity and third-person observation of the brain.     

Formalization of Damasio's theory of emotion, feeling and core consciousness

This paper contributes an analysis and formalization of Damasio's theory on core consciousness. Three important concepts in this theory are 'emotion', 'feeling' and 'feeling a feeling' (or core consciousness). In particular, a simulation model is described of the dynamics of basic mechanisms leading via emotion and feeling to core consciousness, and dynamic properties are formally specified that hold for these dynamics at a more global level. These properties have been automatically checked for the simulation model. Moreover, a formal analysis is made of relevant notions of representation used by Damasio. As part of this analysis, specifications of representation relations have been verified and confirmed against the simulation model.     

Person and consciousness.

My interlocuter is Locke with his reduction of person to personal consciousness. This reduction is a main reason preventing people from acknowledging the personhood of the earliest human embryo, which lacks all personal consciousness. I show that Catholic Christians who live the sacramental life of the Church have reason to think that they are, as persons, vastly more than what they experience themselves to be, for they believe that the sacraments work effects in them as persons that can only be believed but that cannot be experienced within themselves in this life. I also show that Christians and non-Christians alike have an experience of moral good and evil in themselves that implies that they are, as moral persons, far more than they find in their conscious self-presence. It is, therefore, natural to think that if my being a person so far exceeds my consciousness, I may well have once existed as person even before the awakening of consciousness.     

The global workspace (GW) theory of consciousness and epilepsy

The global workspace (GW) theory proposes that conscious processing results from coherent neuronal activity between widely distributed brain regions, with fronto-parietal associative cortices as key elements. In this model, transition between conscious and non conscious states are predicted to be caused by abrupt non-linear massive changes of the level of coherence within this distributed neural space. Epileptic seizures offer a unique model to explore the validity of this central hypothesis. Seizures are often characterized by the occurrence of brutal alterations of consciousness (AOC) which are largely negatively impacting patients' lives. Recently, we have shown that these sudden AOC are contemporary to non-linear increases of neural synchrony within distant cortico-cortical and cortico-thalamic networks. We interpreted these results in the light of GW theory, and suggested that excessive synchrony could prevent this distributed network to reach the minimal level of differentiation and complexity necessary to the coding of conscious representations. These observations both confirm some predictions of the GW model, and further specify the physiological window of neural coherence (minimum and maximum) associated with conscious processing.