The idea that the thalamo-cortical system is the crucial constituent of the neurobiological mechanisms of consciousness has a long history. For the last few decades, however, consciousness research has to a large extent overlooked the interplay between the cortex and thalamus. Here we revive an integrated view of the neurobiology of consciousness by presenting and discussing several recent major findings about the role of the thalamocortical interactions in consciousness. Based on these findings we propose a specific cellular mechanism how thalamic (...) nuclei modulate the integration of different processing streams within single cortical pyramidal neurons. This theory is inspired by recent work done in rodents, but it integrates decades of work conducted on various species. We illustrate how this new view readily explains various properties and experimental phenomena associated with conscious experience. We discuss the implications of this idea and some of the experiments that need to be done in order to test it. Our view bridges two long-standing perspectives on the neural mechanisms of consciousness and proposes that cortical and thalamo-cortical processing interact at the level of single pyramidal cells. (shrink)

An object in continuous motion is perceived ahead of the briefly flashed object, although the two images are physically aligned , the phenomenon called flash-lag effect. Flash-lag effects have been found also with other continuously changing features such as color, pattern entropy, and brightness as well as with streamed pre- and post-target input without any change of the feature values of streaming items in feature space . We interpret all instances of the flash-lag as a consequence of a more fundamental (...) property of conscious perception in general: acceleration of the speed with which samples of perceptual information become represented in explicit format immediately after the stimulation onset. Decreased visual latency of the samples of stimulus information from the streamed input leads to the relative perceptual lag for the separately flashed stimulus because it is not preceded by adjacent sensory input that would have accelerated its perception. Experimental support for the notion of perceptual acceleration is reviewed. (shrink)

Two standard epistemological accounts are conflated in Dienes & Perner's account of knowledge, and this conflation requires the rejection of their four conditions of knowledge. Because their four metarepresentations applied to the explicit-implicit distinction are paired with these conditions, it follows by modus tollens that if the latter are inadequate, then so are the former. Quite simply, their account misses the link between true reasoning and knowledge.

Starting with Dienes and Perner’s distinction between explicit and implicit knowledge and the traditional philosophical distinction between COS as an object and COS as a subject, we suggest a triple classification of COS experience into three modes, each corresponding to a different state of consciousness. When one acts automatically COS is totally embedded within the representation of the environment. When one monitors or attends to one’s experience, the self is implied by an explicit representation of one’s attitudes, consistent with Descartes’ (...) cogito insight ‘I think therefore I am’ . However, a reflexive thought, e.g., ‘I know fact x,’ requires an explicit representation of the self. This analysis highlights the existence of an intermediate mode of COS as a subject and suggests its possible connection to monitoring one’s behavior. (shrink)

How do humans manage to keep track of a gradually changing object or person as the same persisting individual despite the fact that the extraction of information about this individual must often rely on heterogeneous information sources and heterogeneous tracking methods? The article introduces the Empirical Tracking of Individuals theory to address this problem. This theory proposes an analysis of the concept of integrated tracking, which refers to the capacity to acquire, store, and update information about the identity and location (...) of individuals in our environment. It hypothesizes that certain functions of attention are a key to explaining how the cognitive flexibility of the human mind overcomes the heterogeneity of sources and methods in integrated tracking. At least two premises lend support to this hypothesis. First, heterogeneity of tracking sources is overcome by the combination of information from multiple perceptual modalities and a phenomenon of multisensory 'transparency'. Second, heterogeneity of tracking sources and methods may also be overcome by inferences that combine information across domains to acquire reasons to believe propositions about the target's location and identity. (shrink)

To have an ontology is to interpret a world. In this paper we argue that the brain, viewed as a representational system aimed at interpreting our world, possesses an ontology too. It creates primitives and makes existence assumptions. It decomposes target space in a way that exhibits a certain invariance, which in turn is functionally significant. We will investigate which are the functional regularities guiding this decomposition process, by answering to the following questions: What are the explicit and implicit assumptions (...) about the structure of reality, which at the same time shape the causal profile of the brain's motor output and its representational deep structure, in particular of the conscious mind arising from it (its ''phenomenal output'')? How do they constrain high-level phenomena like conscious experience, the emergence of a first-person perspective, or social cognition? By reviewing a series of neuroscientific results and integrating them with a wider philosophical perspective, we will emphasize the contribution the motor system makes to this process. As it will be shown, the motor system constructs goals, actions, and intending selves as basic constituents of the world it interprets. It does so by assigning a single, unified causal role to them. Empirical evidence demonstrates that the brain models movements and action goals in terms of multimodal representations of organism-object-relations. Under a representationalist analysis, this process can be conceived of as an internal, dynamic representation of the intentionality-relation itself. We will show how such a complex form of representational content, once it is in place, can later function as a functional building block for social cognition and for a more complex, consciously experienced representation of the first-person perspective as well. (shrink)

The representational dynamics of the brain is a subsymbolic process, and it has to be conceived as an "agent-free" type of dynamical self-organization. However, in generating a coherent internal world-model, the brain decomposes target space in a certain way. In doing so, it defines an "ontology": to have an ontology is to interpret a world. In this paper we argue that the brain, viewed as a representational system aimed at interpreting the world, possesses an ontology too. It decomposes target space (...) in a way that exhibits certain invariances, which in turn are functionally significant. A challenge for empirical research is to determine which are the functional regularities guiding this decomposition process. What are the explicit and implicit assumptions about the structure of reality, which at the same time shape the causal profile of the brain's motor output and the representational deep structure of the conscious mind arising from it (its "phenomenal output")? How do they constrain high-level phenomena like conscious experience, the emergence of a first-person perspective, or social cognition? By reviewing a series of neuroscientific results, we focus on the contribution the motor system makes to this process. As it turns out, the motor system constructs goals, actions, and intending selves as basic constituents of the world it interprets. It does so by assigning a single, unified causal role to them. Empirical evidence now clearly shows how the brain actually codes movements and action goals in terms of multimodal representations of organism-object relations. Under a representationalist analysis, this process can be interpreted as an internal representation of the intentionality relation itself. We try to show how such a more complex form of representational content, once it is in place, can later function as the building block for social cognition and a for more complex, consciously experienced representation of the first-person perspective as well. The motor system may therefore play a decisive role in understanding how the functional ontology of the human brain could be gradually extended into the subjective and social domains. (shrink)

The implicit-explicit distinction is applied to knowledge representations. Knowledge is taken to be an attitude towards a proposition which is true. The proposition itself predicates a property to some entity. A number of ways in which knowledge can be implicit or explicit emerge. If a higher aspect is known explicitly then each lower one must also be known explicitly. This partial hierarchy reduces the number of ways in which knowledge can be explicit. In the most important type of implicit knowledge, (...) representations merely reflect the property of objects or events without predicating them of any particular entity The dearest cases of explicit knowledge of a fact are representations of one's own attitude of knowing that fact. These distinctions are discussed in their relationship to similar distinctions such as procedural-declarative, conscious unconscious, verbalizable-nonverbalizable, direct-indirect tests, and automatic voluntary control. This is followed by an outline of how these distinctions can be used to integrate and relate the often divergent uses of the implicit-explicit distinction in different research areas. We illustrate this for visual perception, memory, cognitive development, and artificial grammar learning. (shrink)

COMMENTARY ON: LaBerge, D. "Attention, Awareness, and the Triangular Circuit". Consciousness and Cognition, 6, 149-181.

LaBerge's Triangular Theory of Attention contributes to several important topics in the study of visual attention. First, it expands on the discussion of whether attentive influences manifest themselves as neural suppression or enhancement; LaBerge seems to favour the enhancement viewpoint. Second, the paper proposes circuit loops that may be responsible for the observed enhancement. Finally, a link between awareness and attention is explored and the claim that a representation of self must be considered is made. Here, it will not be (...) possible to provide sensible discussion on all of these points; rather, the focus will be on the first issue, namely whether attention is manifested as enhancement or suppression. I claim that observations of enhancement or suppression depend very much on exactly how measurements are taken. Specific predictions are made: a given neuron exhibits enhanced or suppressed responses as a result of attentive influence depending on where that neuron is located in relation to the three-dimensional structure of attentive influences within the visual processing network. I show here a local, internal, attention control mechanism as an alternate model that provides an explanation for both enhancement and suppression of neural responses. In addition, it solves an important second problem for attention models, namely, information routing, within the same mechanism. The routing problem seems to be ignored by LaBerge. (shrink)

COMMENTARY ON: LaBerge, D. "Attention, Awareness, and the Triangular Circuit". Consciousness and Cognition, 6, 149-181.

COMMENTARY ON: LaBerge, D.. Attention, awareness, and the triangular circuit. Consciousness and Cognition, 6, 149-181. ABSTRACT: LaBerge proposes that underlying attention and self-awareness is a triangular circuit involving interconnected posterior cortical, thalamic and prefrontal neural ensembles. While the target paper makes only passing reference to it, the reticular nucleus of the thalamus is an integral part of the triangular circuit he posits. Indeed, it is essential to a complete understanding of his model.

COMMENTARY ON: LaBerge, D. "Attention, Awareness, and the Triangular Circuit". Consciousness and Cognition, 6, 149-181.

COMMENTARY ON: LaBerge, D. "Attention, Awareness, and the Triangular Circuit". Consciousness and Cognition, 6, 149-181.

Before one can even begin to model consciousness and what exactly it means that it is a subjective phenomenon one needs a theory about what a first-person perspective really is. This theory has to be conceptually convincing, empirically plausible and, most of all, open to new developments. The chosen conceptual framework must be able to accommodate scientific progress. Its ba- sic assumptions have to be plastic as it were, so that new details and empirical data can continuously be fed into (...) the theoretical model as it grows and becomes more refined. This paper makes an attempt at sketching the outlines of such a theory, offering a representationalist analysis of the phenomenal first-person perspective. Three phenomenal target properties are centrally relevant. (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)

Replies are given to the commentaries of the seven cognitive science experts. Additional circuit diagrams clarify thalamic operations in attention and basal ganglia operations by which motivation affects attention. Selection-by-suppression and negative priming are accounted for within frontal control areas. Confusions between the terms awareness and consciousness persist, owing to the powerful habit of using awareness as a synonym for consciousness. Leaving consciousness as an umbrella term to denote many loosely-defined aspects of experience, the term awareness denotes the aspect of (...) experience in which attention is directed to bodily sensations, thereby involving the self in ongoing experience. The responses to the commentaries are organized under three main headings: anatomical properties of the triangular circuit of attention; functions of the triangular circuit in attention; and relations of attention to awareness and self-awareness. (shrink)

A Bradford Book The MIT Press Cambridge, Massachusetts London, England.