Mathematical Learning Theory and the New "Mental Forestry"

involved in learning can only be described in terms that sound extravagant. It is our task to consider only one part of this remark­ able progress, but in order to put our review in perspective, we begin with a brief sketch of our impression of the current condition of the psychology of learning and cognition. A little more than 10 years ago, experimental psychologists in the field of learning seemed concerned primarily with changes in the frequency of certain response classes over trials as a function of experimental conditions. Since that time a new psychology of cognition has grown up, at least to the point of adoles­ cence, if not young maturity. While it is important to remember that occasional far-sighted theorists and commentators since James (115) and before have seen clearly that cognition is a complex and worthy subject, it is nonetheless true that the emergent techniques and interests in the study of cogni tive processes such as attention, encoding, search strategies, rehearsal processes, and understanding constitute a kind of revolution.'