In recent years there has been an explosion of scientific work on consciousness in cognitive neuroscience, psychology, and other fields. It has become possible to think that we are moving toward a genuine scientific understanding of conscious experience. But what is the science of consciousness all about, and what form should such a science take? This chapter gives an overview of the agenda.

How can we disentangle the neural basis of phenomenal consciousness from the neural machinery of the cognitive access that underlies reports of phenomenal consciousness? We can see the problem in stark form if we ask how we could tell whether representations inside a Fodorian module are phenomenally conscious. The methodology would seem straightforward: find the neural natural kinds that are the basis of phenomenal consciousness in clear cases when subjects are completely confident and we have no reason to doubt their (...) authority, and look to see whether those neural natural kinds exist within Fodorian modules. But a puzzle arises: do we include the machinery underlying reportability within the neural natural kinds of the clear cases? If the answer is ‘Yes’, then there can be no phenomenally conscious representations in Fodorian modules. But how can we know if the answer is ‘Yes’? The suggested methodology requires an answer to the question it was supposed to answer! The paper argues for an abstract solution to the problem and exhibits a source of empirical data that is relevant, data that show that in a certain sense phenomenal consciousness overflows cognitive accessibility. The paper argues that we can find a neural realizer of this overflow if assume that the neural basis of phenomenal consciousness does not include the neural basis of cognitive accessibility and that this assumption is justified by the explanations it allows. (shrink)

A new strategy for moving forward in the characterization of the Global Neuronal Workspace (GNW) is proposed. According to Dehaene, Changeux and colleagues, broadcasting is the main function of the GNW. However, the dynamic network properties described by recent graph-theoretic GNW models are consistent with many large-scale communication processes that are different from broadcasting. We propose to apply a different graph-theoretic approach, originally developed for optimizing information dissemination in communication networks, which can be used to identify the pattern of frequency (...) and phase-specific directed functional connections that the GNW would exhibit only if it were a broadcasting network. (shrink)

To ‘Darwinize’ a debunking argument is to broaden and thereby strengthen it in ways inspired by Charles Darwin. It is to employ Darwinian strategies that converge on the conclusion that certain putative phenomena – the reality of stance‐independent moral properties, for instance – are illusory or epistemically problematic for animals like us. The aim of this essay is to defend one such strategy and illustrate its power relative to most evolutionary debunking arguments currently on offer.

The idea that attention is necessary for consciousness (the “Necessity Thesis”) is frequently advocated by philosophers and psychologists alike. Experiments involving inattentional and change blindness are thought to support the Necessity Thesis, but they do so only if subjects failing to notice the target stimulus are also not conscious of it. This article uses commonsense phenomenological observations supplemented with empirical data to argue that some subjects failing to notice the target stimulus nonetheless experience its color. Since subjects not noticing the (...) target are commonly assumed to be not attending to it, these scenarios would be instances of consciousness without attention: instead of inattentional and change blindness supporting the Necessity Thesis, they would present counterexamples to it. (shrink)

Two debates loom large in current discussions on phenomenal consciousness. One debate concerns the relation between phenomenal character and representational content. Representationalism affirms, whereas “content separatism” denies, that phenomenal character is exhausted by representational content. Another debate concerns the relation between phenomenal consciousness and cognitive access. “Access separatism” affirms, whereas, e.g., the global workspace model denies, that there are phenomenally conscious states that are not cognitively accessed. I will argue that the two separatist views are related. Access separatism supports content (...) separatism by undermining the most prominent sort of arguments in favor of representationalism, namely ones that appeal to the phenomenology of perceptual experiences. (shrink)

Cognitive theories claim, whereas non-cognitive theories deny, that cognitive access is constitutive of phenomenology. Evidence in favor of non-cognitive theories has recently been collected by Block and is based on the high capacity of participants in partial-report experiments compared to the capacity of the working memory. In reply, defenders of cognitive theories have searched for alternative interpretations of such results that make visual awareness compatible with the capacity of the working memory; and so the conclusions of such experiments remain controversial. (...) Instead of entering the debate between alternative interpretations of partial-report experiments, this paper offers an alternative line of research that could settle the discussion between cognitive and non-cognitive theories of consciousness. Here I relate the neural correlates of cognitive access to empirical research into the neurophysiology of dreams; cognitive access seems to depend on the activity of the dorsolateral prefrontal cortex. However, that area is strongly deactivated during sleep; a period when we entertain conscious experiences: dreams. This approach also avoids the classic objection that consciousness should be inextricably tied to reportability or it would fall outside the realm of science. (shrink)

Block [Block, N. . Two neural correlates of consciousness. Trends in Cognitive Science, 9, 46–52] and Snodgrass claim that a signal detection theory analysis of qualitative difference paradigms, in particular the exclusion failure paradigm, reveals cases of phenomenal consciousness without access consciousness. This claim is unwarranted on several grounds. First, partial cognitive access rather than a total lack of cognitive access can account for exclusion failure results. Second, Snodgrass’s Objective Threshold/Strategic model of perception relies on a problematic ‘enable’ approach to (...) perception that denies the possibility of intentional control of unconscious perception and any effect of following different task instructions on the presence/absence of phenomenal consciousness. Many of Block’s purported examples of phenomenal consciousness without cognitive access also rely on this problematic approach. Third, qualitative difference paradigms may index only a subset of access consciousness. Thus, qualitative difference paradigms like exclusion failure cannot be used to isolate phenomenal consciousness, any attempt to do so still faces serious methodological problems. (shrink)

This article deals with the difficulties of the yet intuitive causal interpretation of the mind–body connection emphasized by metaphysical, theoretical and experimental considerations. It shows that a decisive contribution to determining the nature of this connection can be provided experimentally. This experimental test is designed within the framework of a general systems theory capable of representing the concepts of complementarity and entanglement that are involved in the description of the mind–body connection.

Barsalou has recently argued against the strategy of identifying amodal neural representations by using their cross-modal responses (i.e., their responses to stimuli from different modalities). I agree that there are indeed modal structures that satisfy this “cross-modal response” criterion (CM), such as distributed and conjunctive modal representations. However, I argue that we can distinguish between modal and amodal structures by looking into differences in their cross-modal responses. A component of a distributed cell assembly can be considered unimodal because its responses (...) to stimuli from a given modality are stable, whereas its responses to stimuli from any other modality are not (i.e., these are lost within a short time, plausibly as a result of cell assembly dynamics). In turn, conjunctive modal representations, such as superior colliculus cells in charge of sensory integration, are multimodal because they have a stable response to stimuli from different modalities. Finally, some prefrontal cells constitute amodal representations because they exhibit what has been called ‘adaptive coding’. This implies that their responses to stimuli from any given modality can be lost when the context and task conditions are modified. We cannot assign them a modality because they have no stable relation with any input type. (shrink)

Consciousness remains a mystery—“a phenomenon that people do not know how to think about—yet” (Dennett, , p. 21). Here, I consider how the connectionist perspective on information processing may help us progress toward the goal of understanding the computational principles through which conscious and unconscious processing differ. I begin by delineating the conceptual challenges associated with classical approaches to cognition insofar as understanding unconscious information processing is concerned, and to highlight several contrasting computational principles that are constitutive of the connectionist (...) approach. This leads me to suggest that conscious and unconscious processing are fundamentally connected, that is, rooted in the very same computational principles. I further develop a perspective according to which the brain continuously and unconsciously learns to redescribe its own activity itself based on constant interaction with itself, with the world, and with other minds. The outcome of such interactions is the emergence of internal models that are metacognitive in nature and that function so as to make it possible for an agent to develop a (limited, implicit, practical) understanding of itself. In this light, plasticity and learning are constitutive of what makes us conscious, for it is in virtue of our own experiences with ourselves and with other people that our mental life acquires its subjective character. The connectionist framework continues to be uniquely positioned in the Cognitive Sciences to address the challenge of identifying what one could call the “computational correlates of consciousness” (Mathis & Mozer, ) because it makes it possible to focus on the mechanisms through which information processing takes place. (shrink)

The possibility of consciousness in human brain organoids is sometimes viewed as determinative in terms of the moral status such entities possess, and, in turn, in terms of the research protections such entities are due. This commonsense view aligns with a prominent stance in neurology and neuroscience that consciousness admits of degrees. My paper outlines these views and provides an argument for why this picture of correlating degrees of consciousness with moral status and research protections is mistaken. I then provide (...) an alternative account of the correlation between moral status and consciousness, and consider the epistemic ramifications for research protections of this account. (shrink)

Research into the neural correlates of consciousness (NCC) aims to identify not just those brain areas that are NCC, but also those that are not. In the received method for ruling out a brain area from being an NCC, this is accomplished by showing a brain area’s content to be consistently absent from subjects’ reports about what they are experiencing. This paper points out how this same absence can be used to infer that the brain area’s content is cognitively inaccessible, (...) in which case we would expect its content to be absent from subjects’ reports whether its content is (phenomenally) conscious or not. If so, such reports cannot count as evidence against that brain area being an NCC, and the received method fails. An alternative method (one suggested in Block, 2007) is considered. (shrink)

A key question in studying consciousness is how neural operations in the brain can identify streams of sensory input as belonging to distinct modalities, which contributes to the representation of qualitatively different experiences. The basis for identification of modalities is proposed to be constituted by self-organized comparative operations across a network of unimodal and multimodal sensory areas. However, such network interactions alone cannot answer the question how sensory feature detectors collectively account for an integrated, yet phenomenally differentiated experiential content. This (...) problem turns out to be different from, although related to, the binding problem. It is proposed that the neural correlate of an enriched, multimodal experience is constituted by the attractor state of a dynamic associative network. Within this network, unimodal and multimodal sensory maps continuously interact to influence each other’s attractor state, so that a feature change in one modality results in a fast re-coding of feature information in another modality. In this scheme, feature detection is coded by firing-rate, whereas firing phase codes relational aspects. (shrink)

The Language of Thought: A New Philosophical Direction, by SchneiderSusan. Cambridge, MA: MIT Press, 2011. Pp. xii + 259.

People’s awareness of tactile stimuli has been investigated in far less detail than their awareness of stimuli in other sensory modalities. In an attempt to fill this gap, we provide an overview of studies that are pertinent to the topic of tactile consciousness. We discuss the results of research that has investigated phenomena such as “change blindness”, phantom limb sensations, and numerosity judgments in tactile perception, together with the results obtained from the study of patients affected by deficits that can (...) adversely affect tactile perception such as neglect, extinction, and numbsense. The similarities as well as some of the important differences that have emerged when visual and tactile conscious information processing have been compared using similar experimental procedures are highlighted. We suggest that conscious information processing in the tactile modality cannot be separated completely from the more general processing of spatial information in the brain. Finally, the importance of considering tactile consciousness within the larger framework of multisensory information processing is also discussed. (shrink)

Libet discovered that a substantial duration (> 0.5-1.0 s) of direct electrical stimulation of the surface of the somatosensory cortex at threshold currents is required before human subjects can report that a conscious somatosensory experience had occurred. Using a reaction time method we confirm that a similarly long stimulation duration at threshold currents is required for activation of elementary visual experiences (phosphenes) in human subjects following stimulation of the surface of the striate cortex. However, the reaction times for the subject (...) to respond to the cessation of the visual experience after the end of electrical stimulation could be as brief as 225-242 ms. We also carried out extensive studies in cats under a variety of anesthetic conditions using the same electrodes and parameters of stimulation employed in the human studies to study the patterns of neuronal activity beneath the stimulating surface electrode. Whereas sufficiently strong currents can activate neurons within milliseconds, stimulating currents close to threshold activate sustained neural activity only after at least 350-500 ms. When currents are close to threshold, some neurons are inhibited for several hundreds of millisecond before the balance between inhibition and excitation shifts towards excitation. These results suggest that the prolonged latencies, i.e., latencies beyond 200-250 ms, for the emergence of conscious experience following direct cortical stimulation result from a delay in the sustained activation of underlying cortical neurons at threshold currents rather than being due to any unusually long duration in central processing time. Intracellular records from cortical neurological cells during repetitive electrical stimulation of the surface of the feline striate cortex demonstrate that such stimulation induces a profound depolarizing shift in membrane potential that may persist after each stimulus train. Such a depolarization is evidence that extracellular K+ concentrations have increased during electrical stimulation. Such an increase in extracellular K+ progressively increases cortical excitability until the threshold for sustained activation of cortical neurons is reached and then exceeded. Consequently, the long latency for threshold activation of cortical neurons depends upon a dynamically increasing cortical facilatory process that begins hundreds of milliseconds before there is sustained activation of such neurons. In some cases, this facilatory process must overcome an initial stimulus-induced inhibition before neuronal firing commences. (shrink)

Ned Block’s Overflow Argument purports to establish that the neural basis of phenomenal consciousness is independent of the neural basis of access consciousness. In a recent paper, Block’s argument has been challenged by Peter Carruthers. Carruthers concedes the truth of one of the argument’s key steps, namely, that phenomenal consciousness overflows what is in working memory. At the same time, he rejects the conclusion of the argument by developing an account of this overflow that is alternative to Block’s. In this (...) paper, I argue that Carruthers’s account does not pose a real threat to the Overflow Argument. The overall plausibility of Carruthers’s account rests on the empirical plausibility of a claim concerning global broadcasting which, albeit intuitively plausible in light of a lightly-sketched picture of the impact of attention upon neural matters, he offers no sufficient empirical evidence for. Drawing on some important imaging studies that reveal striking facts about neural responses to visual stimuli, I argue for two intimately related claims: first, that the intuitive plausibility of claims like Carruthers’s is not a guarantee of empirical plausibility; second, that as concerns the same claims, strong empirical evidence is needed before confident judgments of empirical plausibility can reasonably be formulated. (shrink)

This paper examines the possibility of finding evidence that phenomenal consciousness is independent of access. The suggestion reviewed is that we should look for isomorphisms between phenomenal and neural activation spaces. It is argued that the fact that phenomenal spaces are mapped via verbal report is no problem for this methodology. The fact that activation and phenomenal space are mapped via different means does not mean that they cannot be identified. The paper finishes by examining how data addressing this theoretical (...) question could be obtained. (shrink)

1 INSERM-CEA Unit 562, Cognitive Neuroimaging, Service Hospitalier Fre´de´ric Joliot, Orsay, France, 2 CNRS URA2182 Re´cepteurs and Cognition, Institut Pasteur, Paris, France.