["Les liaisons dangereuses": reflections on the optimal psychic ties for mental development].

The activity of linking (i.e. the forming and maintaining of psychic ties), essential for mental functioning, is reviewed with reference to three major psychological trends and their contribution to the understanding of thinking: the cognitivist approach based on Piaget's theory; the studies of early interactions; and the psychoanalytical perspective. The case of a ten year old boy with severe learning difficulties is presented to illustrate certain problems in the coordination process which a specialist can elucidate through psychological assessment. Finally, we discuss the reasons for such dysfunctioning as well as the conditions that favour linking activity.