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)

How internal categories influence how we perceive the world is a fundamental question in cognitive sciences. Yet, the relation between perceptual awareness and perceptual categorization has remained largely uncovered so far. Here, we addressed this question by focusing on face perception during subliminal and conscious perception. We used morphed continua between two face identities and we assessed, through a masked priming paradigm, the perceptual processing of these morphed faces under subliminal and supraliminal conditions. We found that priming from subliminal faces (...) followed linearly the information present in the primes, while priming from visible faces revealed a non-linear profile, indicating a categorical processing of face identities. Our results thus point to a special relation between perceptual awareness and categorical processing of faces, and support the dissociation between two modes of information processing: a subliminal mode involving analog treatment of stimuli information, and a supraliminal mode relying on discrete representation. (shrink)

General anesthesia provides an alternative to typical laboratory paradigms for investigating implicit learning. We assess the evidence that a simple type of learning—priming—can occur without consciousness. Although priming has been shown to be a small but persistent phenomenon in surgical patients there is reason to question whether it occurs implicitly due to problems in detecting awareness using typical clinical signs. This paper reviews the published studies on priming during anesthesia that have included a measure of awareness or of anesthetic depth. (...) We conclude that perceptual priming, but not conceptual priming, takes place in the absence of conscious awareness. (shrink)

This study evaluated the potential contribution of extrageniculate visual pathways to oculomotor orienting reflexes in hemianopic patients. It tested whether extrageniculate pathways mediate inhibition of return —a phenomenon characterized by slowed target detections at recently stimulated locations . Because hemianopic subjects cannot overtly respond to stimuli presented within their hemianopic field, we utilized a spatial cueing paradigm that capitalized on the fact that IOR operates in spatiotopic coordinates. Subjects moved their eyes so that a cue and a target presented at (...) the same spatial location were imaged successively onto blind and seeing portions of their retinas. One hemianopic patient showed a similar IOR effect from cues presented within both the seeing and the hemianopic fields. With a second hemianopic patient, only presentations of the cue to the subject's seeing field produced IOR. The explanation for this discrepancy is not evident. These observations highlight both the potential value and the pitfalls inherent in using “blindsight” as a window into human consciousness. (shrink)

By hypothesis, awareness is involved in the modulation of feedback from semantics to the lexical level in the visual word recognition system. When subjects are aware of the fact that there are many related prime–target pairs in a semantic priming experiment, this knowledge is used to configure the system to feed activation back from semantics to the lexical level so as to facilitate processing. When subjects are unaware of this fact, the default set is maintained in which activation is not (...) fed back from semantics to the lexical level so as to conserve limited resources. Qualitative differences in the pattern of data from two lexical decision experiments that employ masked priming are consistent with this hypothesis. Semantic context and stimulus quality interact when the prime is processed with awareness whereas these same two factors produce additive effects on RT when the prime is unlikely to have been processed with awareness. These experiments thus illustrate one way in which awareness affects the dynamics of visual word recognition. (shrink)

Legally blind participants were able to identify a visual stimulus attribute in the absence of consciously identifying its presence. Specifically, participants—with their corrective lenses removed—correctly guessed the hour-hand position above chance on a clockface shown on a computer screen. This occurred both when presented in a 1-clockface display , as well as when shown a display containing 4 clockfaces , in which only 1 face contained a hand. Even more striking, hand identification accuracy in the 4-clockface condition was comparable whether (...) the clockface containing the hand was or was not correctly identified. That legally blind individuals are capable of identifying stimulus attributes without conscious awareness provides an additional vehicle for exploring implicit perception. Consistent with previous research, the visualsystem can apparently cope with degraded visual input through information available through a secondary pathway via the superior colliculi. (shrink)

This study assessed whether real-life stimulus material can elicit conscious and unconscious priming. A typical masked priming paradigm was used, with brand logo primes. We used a rigorous method to assess participants’ awareness of the subliminal information. Our results show that shortly presented and masked brand logos have the power to prime their brand names and, remarkably, words associated to the brand . However, this only occurred when the logos could be categorized clearly above the consciousness threshold. Once the primes (...) were presented close to the consciousness threshold, no subliminal influences on behavior were observed. (shrink)

Using a metacontrast masking paradigm, prior studies have shown that a target’s color information and form information, can be processed without awareness and that unconscious color processing occurs at early, wavelength-dependent levels in the cortical information processing hierarchy. Here we used a combination of paracontrast and metacontrast masking techniques to explore unconscious color and form priming effects produced by blue, green, and neutral stimuli. We found that color priming in normal observers is significantly reduced when an additional paracontrast mask precedes (...) the target at optimal masking SOAs. However, no reduction of form-priming effects was obtained at similar optimal paracontrast SOAs. We conclude that unconscious color priming depends on an early, wavelength- or stimulus-dependent response of color neurons located at early cortical levels whereas unconscious form priming occurs at later levels. (shrink)

Two experiments examine the effects of unreportable hints on anagram solving performance and on solvers' subjective experience of insight. In Experiment 1, after seeing a hint presented too briefly to identify, participants solved anagrams preceded by the solution fastest and solved anagrams preceded by unrelated hints slowest. Participants' “warmth” ratings for solution hints were more insight-like than those for unrelated hints. In Experiment 2 a hint, or no hint, was presented at one of three different exposure durations. Participants benefited from (...) solution-relevant hints that were either unreportable or reportable, but showed a cost only for unrelated hints that were reportable. Participants' ratings of their insight experiences showed that unreportable solution and semantically related hints produced more insight-like experiences than did unrelated hints. The results suggest that unreportable processing of solution-related information is important for the insight experience. (shrink)

Two experiments examine the effects of unreportable hints on anagram solving performance and on solvers' subjective experience of insight. In Experiment 1, after seeing a hint presented too briefly to identify, participants solved anagrams preceded by the solution fastest and solved anagrams preceded by unrelated hints slowest. Participants' “warmth” ratings for solution hints were more insight-like than those for unrelated hints. In Experiment 2 a hint, or no hint, was presented at one of three different exposure durations . Participants benefited (...) from solution-relevant hints that were either unreportable or reportable, but showed a cost only for unrelated hints that were reportable. Participants' ratings of their insight experiences showed that unreportable solution and semantically related hints produced more insight-like experiences than did unrelated hints. The results suggest that unreportable processing of solution-related information is important for the insight experience. (shrink)

It is often assumed that perceptual experience provides evidence about the external world. But much perception can occur unconsciously, as in cases of masked priming or blindsight. Does unconscious perception provide evidence as well? Many theorists maintain that it cannot, holding that perceptual experience provides evidence in virtue of its conscious character. Against such views, I challenge here both the necessity and, perhaps more controversially, the sufficiency of consciousness for perception to provide evidence about the external world. In addition to (...) motivating and defending the idea that unconscious perception can and does often provide evidence, I observe that whether or not perceptual phenomenology is relevant to the evidentiary status of perception depends on the nature of consciousness. And I argue that a well-supported theory of consciousness—higher-order thought theory—invites a striking conclusion: that perceptual phenomenology is not on its own sufficient to provide for evidence of the external world. (shrink)

This essay is a sustained attempt to bring new light to some of the perennial problems in philosophy of mind surrounding phenomenal consciousness and introspection through developing an account of sensory and phenomenal concepts. Building on the information-theoretic framework of Dretske (1981), we present an informational psychosemantics as it applies to what we call sensory concepts, concepts that apply, roughly, to so-called secondary qualities of objects. We show that these concepts have a special informational character and semantic structure that closely (...) tie them to the brain states realizing conscious qualitative experiences. We then develop an account of introspection which exploits this special nature of sensory concepts. The result is a new class of concepts, which, following recent terminology, we call phenomenal concepts: these concepts refer to phenomenal experience itself and are the vehicles used in introspection. On our account, the connection between sensory and phenomenal concepts is very tight: it consists in different semantic uses of the same cognitive structures underlying the sensory concepts, such as the concept of red. Contrary to widespread opinion, we show that information theory contains all the resources to satisfy internalist intuitions about phenomenal consciousness, while not offending externalist ones. A consequence of this account is that it explains and predicts the so-called conceivability arguments against physicalism on the basis of the special nature of sensory and phenomenal concepts. Thus we not only show why physicalism is not threatened by such arguments, but also demonstrate its strength in virtue of its ability to predict and explain away such arguments in a principled way. However, we take the main contribution of this work to be what it provides in addition to a response to those conceivability arguments, namely, a substantive account of the interface between sensory and conceptual systems and the mechanisms of introspection as based on the special nature of the information flow between them. (shrink)

The traditional model of human cognition (TMHC) postulates an ontological and/or structural gap between conscious and unconscious mental representations. By and large, it sees higher-level mental processes as commonly conceptual or symbolic in nature and therefore conscious, whereas unconscious, lower-level representations are conceived as non-conceptual or sub-symbolic. However, experimental evidence belies this model, suggesting that higher-level mental processes can be, and often are, carried out in a wholly unconscious way and/or without conceptual representations, and that these can be processed unconsciously. (...) This entails that the TMHC, as well as the theories on mental representation it motivates and that in turn support it, is wrong. (shrink)

A series of five experiments investigated the extent of subliminal processing of negation. Participants were presented with a subliminal instruction to either pick or not pick an accompanying noun, followed by a choice of two nouns. By employing subjective measures to determine individual thresholds of subliminal priming, the results of these studies indicated that participants were able to identify the correct noun of the pair – even when the correct noun was specified by negation. Furthermore, using a grey-scale contrast method (...) of masking, Experiment 5 confirmed that these priming effects were evidenced in the absence of partial awareness, and without the effect being attributed to the retrieval of stimulus–response links established during conscious rehearsal. (shrink)

Previous studies suggested that emotions can be correctly interpreted from facial expressions in the absence of conscious awareness of the face. Our goal was to explore whether subordinate information about a face’s gender and race could also become available without awareness of the face. Participants classified the race or the gender of unfamiliar faces that were ambiguous with regard to these dimensions. The ambiguous faces were preceded by face-images that unequivocally represented gender and race, rendered consciously invisible by simultaneous continuous-flash-suppression. (...) The classification of ambiguous faces was biased away from the category of the adaptor only when it was consciously visible. The duration of subjective visibility correlated with the aftereffect strength. Moreover, face identity was consequential only if consciously perceived. These results suggest that while conscious awareness is not needed for basic level categorization, it is needed for subordinate categorization. Emotional information might be unique in this respect. (shrink)

In masked priming tasks responses are usually faster when prime and target require identical rather than different responses. Previous research has extensively manipulated the nature and number of response-affording stimuli. However, little is known about the constraints of masked priming regarding the nature and number of response alternatives. The present study explored the limits of masked priming in a six-choice reaction time task, where responses from different fingers of both hands were required. We studied participants that were either experts for (...) the type of response or novices. Masked primes facilitated responding to targets that required the same response, responses with a different finger of the same hand, and with a homologous finger of the other hand. These effects were modulated by expertise. The results show that masked primes facilitate responding especially for experts in the S–R mapping and with increasing similarity of primed and required response. (shrink)

In vision research metacontrast masking is a widely used technique to reduce the visibility of a stimulus. Typically, studies attempt to reveal general principles that apply to a large majority of participants and tend to omit possible individual differences. The neural plasticity of the visual system, however, entails the potential capability for individual differences in the way observers perform perceptual tasks. We report a case of perceptual learning in a metacontrast masking task that leads to the enhancement of two types (...) of adult human observers despite identical learning conditions. In a priming task both types of observers exhibited the same priming effects, which were insensitive to learning. Findings suggest that visual processing of target stimuli in the metacontrast masking task is based on neural levels with sufficient plasticity to enable the development of two types of observers, which do not contribute to processing of target stimuli in the priming task. (shrink)

Consciousness is central to our lived experience. It is unsurprising, then, that the topic has captivated many students, neuroscientists, philosophers, and other theorists working in cognitive science. But consciousness may seem especially difficult to explain. This is in part because the term “consciousness” has been used in many different ways. The goal of this chapter is to explore several kinds of consciousness: what theorists have called “creature,” “phenomenal,” “access,” “state,” “transitive,” “introspective,” and “self” consciousness. The basic distinctions among these kinds (...) of consciousness are described in Section 1. Section 2 raises potential challenges for explaining these varieties of consciousness and describes a few current theories of them. Section 3 closes the chapter by exploring directions for future work in the cognitive science of consciousness. Along the way, some of the possible interrelationships among these kinds of consciousness are discussed. (shrink)

Previous research has shown implicit semantic processing of faces or pictures, but whether symbolic carriers such as words can be processed this way remains controversial. Here we examine this issue by adopting the continuous flash suppression paradigm to ensure that the processing undergone is indeed unconscious without the involvement of partial awareness. Negative or neutral words projected into one eye were made invisible due to strong suppression induced by dynamic-noise patterns shown in the other eye through binocular rivalry. Inverted and (...) scrambled words were used as controls to provide baselines at orthographic and feature levels, respectively. Compared to neutral words, emotion-described and emotion-induced negative words required longer time to release from suppression, but only for upright words. These results suggest that words can be processed unconsciously up to semantic level since under interocular suppression completely invisible words can lead to different processing speed due to the emotion information they carry. (shrink)

The same-order representation theory of consciousness holds that conscious mental states represent both the world and themselves. This complex representational structure is posited in part to avoid a powerful objection to the more traditional higher-order representation theory of consciousness. The objection contends that the higher-order theory fails to account for the intimate relationship that holds between conscious states and our awareness of them--the theory 'divides the phenomenal labor' in an illicit fashion. This 'failure of intimacy' is exposed by the possibility (...) of misrepresentation by higher-order states. In this paper, I argue that despite appearances, the same-order theory fails to avoid the objection, and thus also has troubles with intimacy. (shrink)

This article discusses how sequential sampling models can be integrated in a cognitive architecture. The new theory Retrieval by Accumulating Evidence in an Architecture (RACE/A) combines the level of detail typically provided by sequential sampling models with the level of task complexity typically provided by cognitive architectures. We will use RACE/A to model data from two variants of a picture–word interference task in a psychological refractory period design. These models will demonstrate how RACE/A enables interactions between sequential sampling and long-term (...) declarative learning, and between sequential sampling and task control. In a traditional sequential sampling model, the onset of the process within the task is unclear, as is the number of sampling processes. RACE/A provides a theoretical basis for estimating the onset of sequential sampling processes during task execution and allows for easy modeling of multiple sequential sampling processes within a task. (shrink)

A classical definition of automaticity establishes that automatic processing occurs without attention or consciousness, and cannot be controlled. Previous studies have demonstrated that semantic priming can be reduced if attention is directed to a low-level of analysis. This finding suggests that semantic processing is not automatic since it can be controlled. In this paper, we present two experiments that demonstrate that semantic processing may occur in the absence of attention and consciousness. A negative semantic priming effect was found when a (...) low-level prime-task was required and when a masked lexical decision prime-task was performed . This paper also discusses the limitations of the inhibitory mechanism involved in negative semantic priming effect. (shrink)

The relations between automatic processing and consciousness are discussed in this paper. It is argued that automatic processing should not be identified with the absence of consciousness. The organism has access to representations resulting from automatic processing, but these representations, in contrast to the representations resulting from nonautomatic processing, are not propositional. Therefore monitoring of the process, the defining feature of nonautomatic processing, is not possible.

Three experiments examined contributions of study phase awareness of word identity to subsequent word-identification priming by manipulating visual attention to words at study. In Experiment 1, word-identification priming was reduced for ignored relative to attended words, even though ignored words were identified sufficiently to produce negative priming in the study phase. Word-identification priming was also reduced after color naming relative to emotional valence rating (Experiment 2) or word reading (Experiment 3), even though an effect of emotional valence upon color naming (...) (Experiment 2) indicated that words were identified at study. Thus, word-identification priming was reduced even when word identification occurred at study. Word-identification priming may depend on awareness of word identity at the time of study. (shrink)

The aim of this paper is to argue that what I call the simple theory of introspection can be extended to account for our introspective knowledge of what we believe as well as what we consciously experience. In section one, I present the simple theory of introspection and motivate the extension from experience to belief. In section two, I argue that extending the simple theory provides a solution to Moore’s paradox by explaining why believing Moorean conjunctions always involves some degree (...) of irrationality. In section three, I argue that it also solves the puzzle of transparency by explaining why it’s rational to answer the question whether one believes that p by answering the question whether p. Finally, in section four, I defend the simple theory against objections by arguing that self-knowledge constitutes an ideal of rationality. (shrink)

In a series of three experiments, we explored the nature of implicit representations in change blindness . Using 3 × 3 letter arrays, we asked subjects to locate changes in paired arrays separated by 80 ms ISIs, in which one, two or three letters of a row in the second array changed. In one testing version, a tone followed the second array, signaling a row for partial report . In the other version, no PR was required. After Ss reported whether (...) a change had been detected and the PR had been completed , they were asked to identify a degraded letter trigram that was either novel, or from a previously shown row . Our findings indicate that when CB occurs, both the pre-change and post-change stimulus information primes despite its unavailability to consciousness. Surprisingly, findings also indicate that when change detection occurs only the post-change information primes. (shrink)

The present study applies a new method for investigating dynamic unconscious processes. The method consists of selection of words from patient interview and test protocols that in the clinicians' judgments capture the patients' conscious symptom experience and the hypothetical unconscious conflict related to the symptom, subliminal and supraliminal presentation of these words, signal analysis of event-related potentials obtained to the word presentations. Eight phobics and three patients suffering from pathological grief reactions served as subjects. A time-frequency ERP analysis revealed that (...) subjects' ERPs classified the unconscious conflict words better subliminally than supraliminally, while the reverse was true for the conscious symptom words = 2.82, p = .011). The relationship between frequency and latency revealed a similar mirror image pattern for the unconscious conflict and conscious symptom words . This method demonstrated that objective, brain-based evidence for unconscious conflict can be obtained. (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)

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)

To which extent is it justified to adopt Kant as a godfather of cognitive science? To prepare the stage for an answer of this question, we need to set aside Kant’s general transcendental approach to the mind which is radically anti-empiricist and instead turn our attention to his specific topics and claims regarding the mind which are often not focus of Kant’s epistemological investigations. If someone is willing to take this stance, it turns out that there are many bridges connecting (...) Kant with contemporary cognitive science. We investigate possible bridges suggested in the literature between some of Kant’s central claims about consciousness, mental content, and functions of mind, and some specific treatments of these topics in contemporary philosophy of mind and cognitive science. While doing so, we offer additional arguments for some proposed bridges, reconstruct others and completely destroy still other bridges by demonstrating that some suggested links between Kant and cognitive science remain only apparent. (shrink)

Research into intuitive problem solving has shown that objective closeness of participants’ hypotheses were closer to the accurate solution than their subjective ratings of closeness. After separating conceptually intuitive problem solving from the solutions of rational incremental tasks and of sudden insight tasks, we replicated this finding by using more precise measures in a conceptual problem-solving task. In a second study, we distinguished performance level, processing style, implicit knowledge and subjective feeling of closeness to the solution within the problem-solving task (...) and examined the relationships of these different components with measures of intelligence and personality. Verbal intelligence correlated with performance level in problem solving, but not with processing style and implicit knowledge. Faith in intuition, openness to experience, and conscientiousness correlated with processing style, but not with implicit knowledge. These findings suggest that one needs to decompose processing style and intuitive components in problem solving to make predictions on effects of intelligence and personality measures. (shrink)