of group therapy known as psychodrama (although the entry on psychodrama claims it is not a form of group therapy). Another recent development in the theory and method of group psychotherapy based on an integration of systems thinking is Yvonne Agazarian's systems-centered therapy (SCT), which sees groups functioning within the principles of system dynamics. Her method of "functional subgrouping" introduces a method of organizing group communication so it is less likely to react counterproductively to differences. SCT also emphasizes the need to recognize the phases of group development and the defenses related to each phase in order to best make sense and influence group dynamics. In the United Kingdom group psychotherapy initially developed independently, with pioneers S. H. Foulkes and Wilfred Bion using group therapy as an approach to treating combat fatigue in the Second World War. Foulkes and Bion were psychoanalysts and incorporated psychoanalysis into group therapy by recognising that transference can arise not only between group members and the therapist but also among group members. Furthermore, the psychoanalytic concept of the unconscious was extended with a recognition of a group unconscious, in which the unconscious processes of group members could be acted out in the form of irrational processes in group sessions. Foulkes developed the model known as group analysis and the Institute of Group Analysis, while Bion was influential in the development of group therapy at the Tavistock Clinic. Bion's approach is comparable to social therapy, first developed in the United States in the late 1970s by Lois Holzman and Fred Newman, which is a group therapy in which practitioners relate to the group, not its individuals, as the fundamental unit of development. The task of the group is to "build the group" rather than focus on problem solving or "fixing" individuals. In Argentina an independent school of group analysis stemmed from the work and teachings of Swiss-born Argentine psychoanalyst Enrique Pichon-Rivière. This thinker conceived of a group-centered approach which, although not directly influenced by Foulkes' work, was fully compatible with it. Therapeutic principles Irvin Yalom proposed a number of therapeutic factors (originally termed curative factors but renamed therapeutic factors in the 5th edition of The Theory and Practice of Group Psychotherapy (1st edition 1970, 5th edition 2005). Universality The recognition of shared experiences and feelings among group members and that these may be widespread or universal human concerns, serves to remove a group member's sense of