Describes the establishment of a psychological space for any set of stimuli by determining metric distances between the stimuli with the probability that a response learned for a stimulus will generalize to the other. (Author/TW)

Projects that soon a complete mechanistic understanding of simple forms of learning will be available. Describes some of the recent advances in neuroscience and psychology in understanding the changes in neural circuits that occur during certain behavioral situations. Suggests that learning involves the activation of second messenger systems. (TW)