Concepts from psychoanalytic self psychology may be valuable in explai
ning confusing clinical experiences in psychotherapy with psychotic pa
tients. In this article, we describe three clinical cases in which the
! patient believed that one of the therapist's body parts was actually
the patient's. This body part ''mixing up'' has traditionally been un
derstood in terms of part objects or transitional objects. We propose
that the twinship selfobject experience provides a better understandin
g and guide to clinical intervention in these circumstances.