If thought about in retrospect, it is perhaps flabbergasting that the study of consciousness was not considered, and could not be considered, part of science. The impact of the behavioral school of psychology was no doubt both a symptom and a cause of this exclusion. The reasons though for excluding the study of consciousness from science are now properly given to historians, for, as this book is an indication of, extensive scientific research is now being done in this area, and this research is a fascinating story. Once thought to be the domain of mysticism and philosophy, research into consciousness has, finally, entered the domain of the laboratory. The arm-chair speculations of Edmund Husserll are now replaced by the fMRI scan and careful observations. In the words of Francis Crick and Christof Koch, who have written an article for this book, "the time to start the scientific attack is now."
The book is a collection of articles written by active researchers in the field. The preface and the introductory article are excellent and not only introduce the reasons for the book but also put the articles in historical perspective. The author addresses the skepticism of some scientists on whether there is any evidence of conscious experience as such. The articles in the book were selected according to their approach as treating "consciousness as a variable", similar to any other topic of scientific inquiry. He is aware of the problems associated with such a view though, since consciousness, he says, cannot be varied "from the inside". Decreasing it will cause us to lose the ability to observe anything, and the consciousness of others is not accessible directly. The author stresses though that contrary to the assertions of some philosophers, consciousness is not beyond scientific study. We need not depend on "plausible intuitions, thought experiments, or rhetorical brilliance", but can instead rely on experiments and testable hypotheses. He calls this a "verifiable phenomenology" in contrast with the philosophical movement of the last century.
The article by George Mandler also expresses this attitude, asserting that the study of consciousness has been plagued with "philosophical, theological, and pedestrian semantic debris". For Mandler, the "mind" refers to the "totality of theoretical processes ascribed to the individual", and this viewpoint, he believes, will avoid the collapse into solipsism and sophistry that so often accompanies the philosophical view of the mind. Mandler gives an excellent overview of some of the approaches taken in the scientific study of consciousness. He also outlines his personal views on the subject, asserting that for him, consciousness is tied to a system of limited capacity, this limitation referring to the number of "functional units" that can be kept in consciousness at a particular point in time. Mandler does believe though that psychologists and philosophers are correct in their assertion that the content of consciousness is not directly available, and so other strategies must be invented to deal with this content. Most interesting though is that the author does not view consciousness as primary, but instead views it merely as one particular mode of processing. Conscious processing of information cannot therefore be said to have more status than processing that does not.
There are many interesting articles in this book, and space constraints do not permit a detailed review here. Some of articles that this reviewer found interesting or exceptionally well written are: 1. "Consciousness and Isomorphism" by Stephen E. Palmer, which addresses the "inverted spectrum argument". This has been a source of philosophical argumentation ever since John Locke first proposed it in 1690, and asks for a demonstration that the visual experience of colors between two individuals are the same, or whether they are spectrally inverted. The author discusses his reasons for rejecting Locke's assertion that there is no way to tell whether the spectrums are indeed inverted without the two persons "getting into each others heads." 2. "Strategies and Models of Selective Attention" by Anne M. Treisman. The author outlines her strategies for classifying attention tasks and experimental procedures to study them. She restricts herself to tasks that require immediate perception and response, wherein the experimental subjects are subjected to information overload. Her goal is to find out to what extent the mechanisms of selective attention can be encapsulated into a single mechanism. 3. "Aspects of the Theory of Comprehension, Memory, and Attention" by Donald G. MacKay, which attempts to provide evidence for a "modern" version of Wundt's theory, the latter of which asserted that the processing of sentences takes place at two distinct levels, one involving preattentive processes and the other attentive ones. The "modern" version asserts that the perceptual mechanism consists of two distinct and interrelated levels of components, with the first involving limited capacity short-term memory, and the second a large long-term memory. 4. The article "Conscioussness and Complexity" by Giulio Tononi and Gerald M. Edelman. This article, like all the rest in the last part of the book, called "Theory" is fascinating, again because of its attempt to respect the role of experiments. The authors attempt to identify the types of neural processes that account for the key properties of conscious experience, emphasizing that conscious experience is integrated but simultaneously also highly differentiated in that one can experience a large number of different conscious states within a short time. The authors discuss tools for measuring integration, which they call 'functional clustering' and for measuring differentiation, which they call 'neural complexity'. Then they give criteria for determining whether in fact a group of active neurons can contribute to conscious experience. These criteria are encapsulated into the 'dynamic core hypothesis', which they claim is a testable hypothesis on neural contributions to conscious experience. Recent experimental findings are discussed that, in the author's view, show that this hypothesis is viable. These measurements of neural activity shed light on what kind of neural circuits are needed to perform different types of tasks, these tasks sometimes needing conscious control, and sometimes not.