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)

Face perception, perhaps the most highly developed visual skill in humans, is mediated by a distributed neural system in humans that is comprised of multiple, bilateral regions. We propose a model for the organization of this system that emphasizes a distinction between the representation of invariant and changeable aspects of faces. The representation of invariant aspects of faces underlies the recognition of individuals, whereas the representation of changeable aspects of faces, such as eye gaze, expression, and lip movement, underlies the (...) perception of information that facilitates social communication. The model is also hierarchical insofar as it is divided into a core system and an extended system. The core system is comprised of occipitotemporal regions in extrastriate visual cortex that mediate the visual analysis of faces. In the core system, the representation of invariant aspects is mediated more by the face-responsive region in the fusiform gyrus, whereas the representation of changeable aspects is mediated more by the face-responsive region in the superior temporal sulcus. The extended system is comprised of regions from neural systems for other cognitive functions that can be recruited to act in concert with the regions in the core system to extract meaning from faces. (shrink)

Face perception plays a central role in social communication and is, arguably, one of the most sophisticated visual perceptual skills in humans. The organization of neural systems for face perception has stimulated intense debate. This article presents an updated model of distributed human neural systems for face perception. It opens up with a discussion of the Core System for visual analysis of faces with an emphasis on the distinction between perception of invariant features for identity recognition and changeable features for (...) recognition of facial gestures such as expression and eye gaze. The study analyses the roles of systems for the representation of emotion, for person knowledge, and for action understanding in face recognition and perception of expression and gaze. It presents systems that are of particular relevance for social communication and that are illustrative of how distributed systems are engaged by face perception. It concludes with a discussion of modularity and distributed processing in neural representation. (shrink)

The recognition memory for inverted faces is especially difficult when compared with that for non-face stimuli. This face inversion effect has often been used as a marker of face-specific holistic processing. However, whether face processing without awareness is still specific remains unknown. The present study addressed this issue by examining the face inversion effect with the technique of binocular rivalry. Results showed that invisible upright faces could break suppression faster than invisible inverted faces. Nevertheless, no difference was found for invisible (...) upright houses and invisible inverted houses. This suggested that face processing without awareness is still specific. Some face-specific information can be processed by high-level brain areas even when that information is invisible. (shrink)

A substantial body of research has established that even when we are not consciously aware of the faces of others we are nevertheless sensitive to, and impacted by their facial expression. In this paper, we consider this body of research from a new perspective by examining the functions of unconscious perception revealed by these studies. A consideration of the literature from this perspective highlights that existing research methods are limited when it comes to revealing possible functions of unconscious perception. The (...) critical shortcoming is that in all of the methods, the perceived facial expression remains outside of awareness. This is a problem because there are good reasons to believe that one important function of unconsciously perceived negative faces is to attract attention so that they are consciously perceived; such conscious perception, however, is never allowed with existing methodologies. We discuss recent studies of emotional face perception under conditions of visual search that address this issue directly. Further, we suggest that methodologies that do not examine cognitive processes as they occur in more natural settings may result in fundamental misunderstandings of human cognition. (shrink)