behavioral systems model, a framework originating in psychology as behavioral systems theory (BST) extended by Dorothy E. Johnson to describe factors that may affect the stability of a person’s behavior. The model examines systems of behavior, not the behavior of an individual at any particular time. In one model, behavior is defined as an integrated response to stimuli. Several subsystems of behavior form the eight human microsystems, which are ingestion, elimination, dependency, sex, achievement, affiliation, aggression, and restoration. Each subsystem comprises several structural components called imperatives, which are goal, set, choice, action, and support. The goal of nursing care is to attain, maintain, or restore balance of the subsystems of behavior for the stability of the patient.