Cybernetics and Systems: An International Journal, 18:489-515, 1987 SIMULATION OF THE DEVELOPMENT OF INDIVIDUAL INTERACTIONAL PATTERNS A. SILVESTRI~ L. MlCH University of Trento, Italy 0. GOUVElA PEREIRA C. PINTO FERREIRA New University of Lisbon, Portugal The questions of how and why individuals develop normal or abnormal intcrper- sonal patterns have received nonconsistent answers in the behavioral sciences. perhaps because they were t w much concerned with the semantics and the syntax aspects of the communication process that mediates human interaction. This pa- per demonstrates that a pragmnric approach is necessary and sufficient to answer the above questions. The information processing aspect of the "single bit of information exchange" model (P. De Giacomo and A. Silvestri, 1979) is devel- oped to create a computer simulation procedure. Using both clinical datn and normal population measurements of KALTEST (0. G. Pereira and C. P. Fer- reira, 1984) as the basic criteria, it is found that the development of a :;table normal pattern of interaction depends on the ability to share proposals with the other significant person in the environment and that the development of an abnor- mal pattern depends on refusal to share coupled with a tendency to escape from the ring of the interaction. If we ask behavioral scientists how and why individuals develop specific interpersonal mechanism, their answers may be divided roughly into two groups. In one group we find mostly that the answers of psychologists- which refer to individual motivation, learning, and cognitive theories-use +~eceased. Supported by international program C.N.R.-I.N.I.C.