In studies of social interaction, displays, negotiation and transmission of knowledge and the emergence of common ground usually are researched on the level of sequences of interaction, e.g., question-answer, instruction-compliance, etc. However, it is evident that common ground between participants emerges over extended series of interactions as well. In addition to sequences, cross-sequential and cross-event relationships of adding to, updating of, and revising common ground play an important role for the emergence of shared knowledge, social relationships, and the accomplishment of joint action. However, interactional histories that span over series of interactions have only very rarely been studied yet, and they pose very specific requirements on data-sampling.

In my talk, I will report on a study of the emergence and change of common ground over the course of psychotherapy sessions. I will track how therapist and patient, starting with divergent understandings of the sources of patient’s problems, come to develop a shared view over iterated topicalizations of the same conceptual domains pertaining to the patient’s problems. I will show that the development of common ground not only has a prospective, emerging dimension, but also a retrospective dimension: Participants presuppose and refer back to concepts, positions, and agreements that have been established on prior occasions by various explicit and indexical means. In this way they make use of their shared interactional history as a resource of economical and partner-specific recipient design that rests on shared meanings, which at times can be intransparent to an overhearer who does not know their history. Data come from psychodynamic psychotherapy in German.