APA Dictionary of Psychology

in general, any conceptual analysis that assumes that the processes contributing to group development fluctuate around, but regularly return to, a resting point where opposing forces are balanced or held in check. For example, U.S. social psychologist Robert Freed Bales (1916–2004) suggested that groups vary over time in the extent to which they stress the accomplishment of group tasks relative to the improvement of interpersonal relationships among group members.