To understand the endogenous components of the event-related brain potential (ERP), we must use data about the components' antecedent conditions to form hypotheses about the information-processing function of the underlying brain activity. These hypotheses, in turn, generate testable predictions about the consequences of the component. We review the application of this approach to the analysis of the P300 component. The amplitude of the P300 is controlled multiplicatively by the subjective probability and the task relevance of the eliciting events, whereas its (...) latency depends on the duration of stimulus evaluation. These and other factors suggest that the P300 is a manifestation of activity occurring whenever one's model of the environment must be revised. Tests of three predictions based on this “context updating” model are reviewed. Verleger's critique is based on a misconstrual of the model as well as a partial and misleading reading of the relevant literature. (shrink)

Stephen Cole Kleene was one of the greatest logicians of the twentieth century and this book is the influential textbook he wrote to teach the subject to the next generation. It was first published in 1952, some twenty years after the publication of Godel's paper on the incompleteness of arithmetic, which marked, if not the beginning of modern logic. The 1930s was a time of creativity and ferment in the subject, when the notion of computable moved from the realm of (...) philosophical speculation to the realm of science. This was accomplished by the work of Kurt Gode1, Alan Turing, and Alonzo Church, who gave three apparently different precise definitions of computable. When they all turned out to be equivalent, there was a collective realization that this was indeed the right notion. Kleene played a key role in this process. One could say that he was there at the beginning of modern logic. He showed the equivalence of lambda calculus with Turing machines and with Godel's recursion equations, and developed the modern machinery of partial recursive functions. This textbook played an invaluable part in educating the logicians of the present. It played an important role in their own logical education.". (shrink)

Henri Bergson (1859-1941) is one of the truly great philosophers of the modernist period, and there is currently a major renaissance of interest in his unduly neglected texts and ideas amongst philosophers, literary theorists, and social theorists. Creative Evolution (1907) is the text that made Bergson world-famous in his own lifetime; in it Bergson responds to the challenge presented to our habits of thought by modern evolutionary theory, and attempts to show that the theory of knowledge must have its basis (...) in a theory of life. (shrink)

Theories of binding have recently come into the focus of the consciousness debate. In this review, we discuss the potential relevance of temporal binding mechanisms for sensory awareness. Specifically, we suggest that neural synchrony with a precision in the millisecond range may be crucial for conscious processing, and may be involved in arousal, perceptual integration, attentional selection and working memory. Recent evidence from both animal and human studies demonstrates that specific changes in neuronal synchrony occur during all of these processes (...) and that they are distinguished by the emergence of fast oscillations with frequencies in the gamma-range. (shrink)

Advances in neuroscience implicate reentrant signaling as the predominant form of communication between brain areas. This principle was used in a series of masking experiments that defy explanation by feed-forward theories. The masking occurs when a brief display of target plus mask is continued with the mask alone. Two masking processes were found: an early process affected by physical factors such as adapting luminance and a later process affected by attentional factors such as set size. This later process is called (...) masking by object substitution, because it occurs whenever there is a mismatch between the reentrant visual representation and the ongoing lower level activity. Iterative reentrant processing was formalized in a computational model that provides an excellent fit to the data. The model provides a more comprehensive account of all forms of visual masking than do the long-held feed-forward views based on inhibitory contour interactions. (shrink)

Linking the process of rational decision making to emotions, an award-winning scientist who has done extensive research with brain-damaged patients notes the dependence of thought processes on feelings and the body's survival-oriented regulators. 50,000 first printing.

Little, Brown, 1992 Review by Glenn Branch on Jul 5th 1999 Volume: 3, Number: 27.

The prefrontal cortex has long been suspected to play an important role in cognitive control, in the ability to orchestrate thought and action in accordance with internal goals. Its neural basis, however, has remained a mystery. Here, we propose that cognitive control stems from the active maintenance of patterns of activity in the prefrontal cortex that represent goals and the means to achieve them. They provide bias signals to other brain structures whose net effect is to guide the flow of (...) activity along neural pathways that establish the proper mappings between inputs, internal states, and outputs needed to perform a given task. We review neurophysiological, neurobiological, neuroimaging, and computational studies that support this theory and discuss its implications as well as further issues to be addressed. (shrink)

Henri Bergson (1859-1941) is one of the truly great philosophers of the modernist period, and there is currently a major renaissance of interest in his unduly neglected texts and ideas amongst philosophers, literary theorists, and social theorists. Creative Evolution (1907) is the text that made Bergson world-famous in his own lifetime; in it Bergson responds to the challenge presented to our habits of thought by modern evolutionary theory, and attempts to show that the theory of knowledge must have its basis (...) in a theory of life. (shrink)

The problem of free will lies at the heart of modern scientific studies of consciousness. Some authors propose that actions are unconsciously initiated and awareness of intention is referred retrospectively to the action after it has been performed [e.g. Aarts, H., Custers, R., & Wegner, D. M. . On the inference of personal authorship: Enhancing experienced agency by priming effect information. Consciousness & Cognition, 14, 439–458]. This contrasts with the common impression that our intentions cause those actions. By combining a (...) stop signal paradigm and an intentional action paradigm we show that participants sometimes indicate to have intentionally initiated an action while reaction time data strongly suggest that they in fact failed to stop the action. In a second experiment we demonstrate that the number of trials in which participants misattributed their awareness of intention varied with the intentional involvement during action planning. Our data support the retrospective account of intentional action. Furthermore, we introduce an experimental approach that objectifies introspective judgments of awareness of intention. (shrink)

This long-awaited work by prominent Harvard psychologist Stephen Kosslyn integrates a twenty-year research program on the nature of high-level vision and mental ...

Leading theorists examine the self-representational theory of consciousness as an alternative to the two dominant reductive theories of consciousness, the ..

Having a self is associated with important advantages for an organism.These advantages have been suggested to include mechanisms supporting elaborate capacities for planning, decision-making, and behavioral control. Acknowledging such functionality offers possibilities for obtaining traction on investigation of neural correlates of selfhood. A method that has potential for investigating some of the brain-based properties of self arising in behavioral contexts varying in requirements for such behavioral guidance and control is functional brain imaging. Data obtained with this method are beginning to (...) converge on a set of brain areas that appear to play a significant role in permitting conscious access to representational content having reference to self as an embodied and independent experiencer and agent. These areas have been identified in a variety of imaging contexts ranging from passive state conditions in which they appear to manifest ongoing activity associated with spontaneous and typically ‘self-related’ cognition, to tasks targeting explicitly experienced properties of self, to demanding task conditions where activity within them is attenuated in apparent redirection of cognitive resources in the service of task guidance and control. In this paper, these data will be reviewed and a hypothesis presented regarding a significant role for these areas in enabling degrees of self-awareness and participating in the management of such behavioral control. (shrink)

The ancient dualism of a sensible and an intelligible world important in Neoplatonic and medieval philosophy, down to Descartes and Kant, would seem to be supplanted today by a scientific view of mind-in-nature. Here, we revive the old dualism in a modified form, and describe mind as a symbolic language, founded in linguistic recursive computation according to the Church-Turing thesis, constituting a world L that serves the human organism as a map of the Universe U. This methodological distinction of L (...) vs. U helps to understand how and why structures of phenomena come to be opposed to their nature in human thought, a central topic in Heideggerian philosophy. U is uncountable according to Georg Cantor’s set theory but Language L, based on the recursive function system, is countable, and anchored in a Gray Area within U of observable phenomena, typically symbols, prelinguistic structures, genetic-historical records of their origins. Symbols, the phenomena most familiar to mathematicians, are capable of being addressed in L-processing. The Gray Area is the human Environment E, where we can live comfortably, that we manipulate to create our niche within hostile U, with L offering overall competence of the species to survive. The human being is seen in the light of his or her linguistic recursively computational mind. Nature U, by contrast, is the unfathomable abyss of being, infinite labyrinth of darkness, impenetrable and hostile to man. The U-man, biological organism, is a stranger in L-man, the mind-controlled rational person, as expounded by Saint Paul. Noumena can now be seen to reside in L, and are not fully supported by phenomena. Kant’s noumenal cause is the mental L-image of only partly phenomenal causation. Mathematics occurs naturally in pre-linguistic phenomena, including natural laws, which give rise to pure mathematical structures in the world of L. Mathematical foundation within philosophy is reversed to where natural mathematics in the Gray Area of pre-linguistic phenomena can be seen to be a prerequisite for intellectual discourse. Lesser, nonverbal versions of L based on images are shared with animals. (shrink)

Over a long career, Libet has conducted experiments that have shown, in clear and concrete ways, how the brain produces conscious awareness.

One of the cornerstone books of Western philosophy, Critique of Pure Reason is Kant's seminal treatise, where he seeks to define the nature of reason itself and builds his own unique system of philosophical thought with an approach known as transcendental idealism. He argues that human knowledge is limited by the capacity for perception and attempts a logical designation of two varieties of knowledge: a posteriori, the knowledge acquired through experience; and a priori, knowledge not derived through experience. This accurate (...) translation by J. M. D. Meiklejohn offers a simple and direct rendering of Kant's work that is suitable for readers at all levels. (shrink)