A T-group or training group (sometimes also referred to as sensitivity-training group, human relations training group or encounter group) is a form of group training where participants (typically between eight and fifteen people) learn about themselves (and about small group processes in general) through their interaction with each other. They use feedback, problem solving, and role play to gain insights into themselves, others, and groups. Experimental studies have been undertaken with the aim of determining what effects, if any, participating in a T-group has on the participants. For example, a 1975 article by Nancy E. Adler and Daniel Goleman concluded that "Students who had participated in a T-group showed significantly more change toward their selected goal than those who had not." Carl Rogers described sensitivity groups as "...the most significant social invention of the century". Concept The concept of encounter as "a meeting of two, eye to eye, face to face," was articulated by J.L. Moreno in Vienna in 1914–15, in his "Einladung zu einer Begegnung" ("Invitation to an Encounter"), maturing into his psychodrama therapy. It was pioneered in the mid-1940s by Moreno's protege Kurt Lewin and his colleagues as a method of learning about human behavior in what became the National Training Laboratories (also known as the NTL Institute) that was created by the Office of Naval Research and the National Education Association in Bethel, Maine, in 1947. First conceived as a research technique with a goal to change the standards, attitudes and behavior of individuals, the T-group evolved into educational and treatment schemes for non-psychiatric patient people. A T-group meeting does not have an explicit agenda, structure, or expressed goal. Under the guidance of a facilitator, the participants are encouraged to share emotional reactions (for example, anger, fear, warmth, or envy) that arise in response to their fellow participants' actions and statements. The emphasis is on sharing emotions, as opposed to judgments or conclusions. In this way, T-group participants can learn how their words and actions trigger emotional responses in the people they communicate with. Group types There are a number of group types. Task groups focus on the here and now, involving learning through doing, activity and processing; and involves daily living skills and work skills. Evaluative groups focus on evaluating the skills, behaviors, needs, and functions of a group and is the first step in a group process. Topical discussion groups focus on a common topic