The papers represented in this collection are the outcome of a program of clinical research initiated about 10 years ago with the publication of my book Mind, Brain and Consciousness ( Brown, 1977). This monograph -- little more than an outline of a theory at the time -- sought to develop a new approach to the interpretation of symptoms of brain injury, one based on the concept of microgenesis. A central feature of this approach is the assumption that the symptoms of brain damage represent normal stages in the microtemporal processing of cognitions and behaviors. Symptoms are not aberrations that point to defective mechanisms, but have a deeper meaning. The abnormal behavior that constitutes the symptom is, in reality, a normal processing stage beneath the surface representation. The significance of this interpretation is that the various types of symptoms associated with brain damage -- since they represent stages in normal function -- can be aligned in a series that captures the formative direction of normal processing. Symptoms are data points in clinical investigation, experiments in nature that help us to see -- as research studies often do not -- the processes that occur within cognitive structure.
Working with symptoms in this way, it was possible in broad strokes to reconstruct the stages -- or a theory of the stages -- involved in the production and perception of language. The theory is based on processing rather than on content; that is, on the process through which representations are generated, as opposed to the content of a particular representation -- and it is an approach that is clearly incompatible with existing anatomical models. For one thing, the concept of a flow from one state to the next cannot easily be related to the prevalent notion of centers and connecting pathways. Such concepts are too static to capture the moment-to-moment change inherent in a processing account. The idea that a mechanism or output device located in a special piece of brain tissue is prewired for a given cognitive operation cannot be resolved with changing lesion effects over time -- in recovery or deterioration, as well as over the life span -- nor for that matter with changes in symptom pattern in the course of a single examination.
Another problem with the traditional interpretation of brain/behavior relations has to do with the evolutionary perspective upon which microgenesis is