Abstract
A theoretical frame for the description of the interactional behavior of human subject systems is presented. The subject's interactional pattern is defined by a quadruple of coordinates, each coordinate being the probability of transition between elementary states, defined in terms of initial subject states and input information (external stimuli). The mathematical basis is briefly given to formalize the model of the human dyadic interactions (interaction between mullicomponent systems can be similarly treated, but is beyond the scope of the paper). The possibility of studying theoretically the evolution with age of the interactional basic mechanisms of human subjects is investigated. An experiment empirically confirmed the validity of the theoretical predictions on the evolution of the mechanisms of the pragmatics of students (from 6 years of age) up to adults.