A number of ways of taxonomizing human learning have been proposed. We examine the evidence for one such proposal, namely, that there exist independent explicit and implicit learning systems. This combines two further distinctions, between learning that takes place with versus without concurrent awareness, and between learning that involves the encoding of instances versus the induction of abstract rules or hypotheses. Implicit learning is assumed to involve unconscious rule learning. We examine the evidence for implicit learning derived from subliminal learning, (...) conditioning, artificial grammar learning, instrumental learning, and reaction times in sequence learning. We conclude that unconscious learning has not been satisfactorily established in any of these areas. The assumption that learning in some of these tasks is predominantly based on rule abstraction is questionable. When subjects cannot report the “implicitly learned” rules that govern stimulus selection, this is often because their knowledge consists of instances or fragments of the training stimuli rather than rules. In contrast to the distinction between conscious and unconscious learning, the distinction between instance and rule learning is a sound and meaningful way of taxonomizing human learning. We discuss various computational models of these two forms of learning. (shrink)

What makes us conscious? Many theories that attempt to answer this question have appeared recently in the context of widespread interest about consciousness in the cognitive neurosciences. Most of these proposals are formulated in terms of the information processing conducted by the brain. In this overview, we survey and contrast these models. We first delineate several notions of consciousness, addressing what it is that the various models are attempting to explain. Next, we describe a conceptual landscape that addresses how the (...) theories attempt to explain consciousness. We then situate each of several representative models in this landscape and indicate which aspect of consciousness they try to explain. We conclude that the search for the neural correlates of consciousness should be usefully complemented by a search for the computational correlates of consciousness. (shrink)

Reviews evidence which suggests that there may be little or no direct introspective access to higher order cognitive processes. Ss are sometimes unaware of the existence of a stimulus that importantly influenced a response, unaware of the existence of the response, and unaware that the stimulus has affected the response. It is proposed that when people attempt to report on their cognitive processes, that is, on the processes mediating the effects of a stimulus on a response, they do not do (...) so on the basis of any true introspection. Instead, their reports are based on a priori, implicit causal theories, or judgments about the extent to which a particular stimulus is a plausible cause of a given response. This suggests that though people may not be able to observe directly their cognitive processes, they will sometimes be able to report accurately about them. Accurate reports will occur when influential stimuli are salient and are plausible causes of the responses they produce, and will not occur when stimuli are not salient or are not plausible causes. (shrink)

A number of ways of taxonomizing human learning have been proposed. We examine the evidence for one such proposal, namely, that there exist independent explicit and implicit learning systems. This combines two further distinctions, (1) between learning that takes place with versus without concurrent awareness, and (2) between learning that involves the encoding of instances (or fragments) versus the induction of abstract rules or hypotheses. Implicit learning is assumed to involve unconscious rule learning. We examine the evidence for implicit learning (...) derived from subliminal learning, conditioning, artificial grammar learning, instrumental learning, and reaction times in sequence learning. We conclude that unconscious learning has not been satisfactorily established in any of these areas. The assumption that learning in some of these tasks (e.g., artificial grammar learning) is predominantly based on rule abstraction is questionable. When subjects cannot report the rules that govern stimulus selection, this is often because their knowledge consists of instances or fragments of the training stimuli rather than rules. In contrast to the distinction between conscious and unconscious learning, the distinction between instance and rule learning is a sound and meaningful way of taxonomizing human learning. We discuss various computational models of these two forms of learning. (shrink)

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)

This review considers a number of recent theories on the neural basis of consciousness, with particular attention to the theories of Bogen, Crick, Llinás, Newman, and Changeux. These theories allot different roles to various key brain areas, in particular the reticular and intralaminar nuclei of the thalamus and the cortex. Crick's hypothesis is that awareness is a function of reverberating corticothalamic loops and that the spotlight ofintramodalattention is controlled by the reticular nucleus of the thalamus. He also proposed different mechanisms (...) for attention and intention . The current review presents a new hypothesis, based on elements from these hypotheses, includingintermodalattention and olfaction and pain, which may pose problems for Crick's original theory. This work reviews the possible role in awareness and intermodal attention and intention of the cholinergic system in the basal forebrain and the tegmentum; the reticular, the intralaminar, and the dorsomedial thalamic nuclei; the raphe and locus coeruleus; the reticular formation; the ventral striatum and extended amygdala; insula cortex, and other selected cortical areas. Both clinical and basic research data are covered. The conclusion is reached that the brain may work by largely nonlinear parallel processing and much intramodal shifts of attention may be effected by intracortical, or multiple corticothalamic mechanisms . But this is constrained by the functional anatomy of the circuits concerned and waking “awareness” is modulated by the many “nonspecific” systems . But the principal agents for intermodal attention shifts, the “searchlight,” may be two key nuclei of the cholinergic system in the mesencephalon. Clinical loss of consciousness results from damage to these nuclei but not from damage to the cholinergic nucleus basalis of the basal forebrain. (shrink)

Neuroscientists continue to search for 'the' neural correlate of consciousness (NCC). In this article, I argue that a framework in which there are at least two distinct NCCs is increasingly making more sense of empirical results than one in which there is a single NCC. I outline the distinction between phenomenal NCC and access NCC, and show how they can be distinguished by experimental approaches, in particular signal- detection theory approaches. Recent findings in cognitive neuroscience provide an empirical case for (...) two different NCCs. (shrink)

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 specific 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. This framework postulates that, at any given time, many modular cerebral networks are active in parallel and process information in an unconscious manner. An information becomes conscious, however, if the neural population that represents it is mobilized by top-down attentional amplification into a brain-scale state of coherent activity that involves many neurons distributed throughout the brain. The long-distance connectivity of these `workspace neurons' can, when they are active for a minimal duration, make the information available to a variety of processes including perceptual categorization, long-term memorization, evaluation, and intentional action. We postulate that this global availability of information through the workspace is what we subjectively experience as a conscious state. A complete theory of consciousness should explain why some cognitive and cerebral representations can be permanently or temporarily inaccessible to consciousness, what is the range of possible conscious contents, how they map onto specific cerebral circuits, and whether a generic neuronal mechanism underlies all of them. We confront the workspace model with those issues and identify novel experimental predictions. Neurophysiological, anatomical, and brain-imaging data strongly argue for a major role of prefrontal cortex, anterior cingulate, and the areas that connect to them, in creating the postulated brain-scale workspace. (shrink)

The neurosciences have advanced to the point that we can now treat consciousness as a scientific problem like any other. The problem is to explain how brain processes cause consciousness and how consciousness is realized in the brain. Progress is impeded by a number of philosophical mistakes, and the aim of this paper is to remove nine of those mistakes: (i) consciousness cannot be defined; (ii) consciousness is subjective but science is objective; (iii) brain processes cannot explain consciousness; (iv) the (...) problem of ‘qualia’ should be set aside; (v) consciousness is epiphenomenal; (vi) consciousness has no evolutionary function; (vii) a causal account of consciousness is necessarily dualistic; (viii) science is reductionistic, so a scientific account of consciousness would show it reducible to something else; and (ix) an account of consciousness must be an information processing account. (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)

Several forms of dietary learning have been identified in humans. These include flavor–flavor learning, flavor–postingestive learning , and learned satiety. Generally, learning is thought to occur in the absence of contingency or demand awareness. However, a review of the literature suggests that this conclusion may be premature because measures of awareness lack the rigor that is found in studies of other kinds of human learning. If associations do configure outside awareness then this should be regarded as a rare instance of (...) automatic learning. Conversely, if awareness is important, then successful learning may be governed by an individual’s beliefs and predilection to attend to stimulus relationships. For researchers of dietary learning this could be critical because it might explain why learning paradigms have a reputation for being unreliable. Since most food preferences are learned, asking questions about awareness can also tell us something fundamental about everyday dietary control. (shrink)