More than 75 years ago, at the Second All-Russian Psychoneurological Congress, L. S.Vygotsky presented a paper, “Methods of Reflexological and PsychologicalInvestigations,” in which he began to lay the foundation for a unified theory of mind.Vygotsky's concern was that psychology had lost sight of the uniqueness of human mentalfunctioning, which for him resides in our ability to intentionally mediate, and hence regulate, ourbiologically specified mental systems (i.e., in today's jargon, input systems)through culturally determined means. Contemporary sociocultural psychologists, J. V. Wertschin particular, have noted that, although Vygotsky called for the unification of psychology, in hiswritings, he actually paid very little attention to one part of the mental equation—thebiological, or natural, mind. As it turns out, even those who fault Vygotsky for his failure herehave themselves not focused much attention on the contribution of the natural, or what Frawleyrefers to as the computational, mind, preferring instead to concentrate on the socioculturalparameters of cognition. The present book can be seen as an attempt to bring to fruitionVygotsky's earlier vision of a unified psychology.