Stage-by-Stage Formation as a Method of Psychological Investigation

"Stage-by-stage formation of mental actions and concepts" usually works as a pedagogical method or, at best, a method of educational psychology. If one is thinking only of the final, fully formed procedure of formation, on the one hand, and its results, on the other, this is valid. But if one considers what the development of such a method entails, on what it is based, by what it is constrained, and what changes the "mental actions and concepts" being formed or cultivated undergo, then, clearly, a system of requirements is in operation: disclosing to the subject the objective grounds with regard to which he must orient his actions, reorganizing accordingly the material to be learned, and outlining a series of rigorously sequential changes (of both actions and the concepts of the objects of those actions) to the point even of forming new, strictly mental phenomena.