The Roy Adaptation Model for Nursing had its beginning when Sr. Callista Roy entered the masters program in pediatric nursing at University of California Los Angeles in 1964. Her advisor and seminar faculty was Dorothy E. Johnson who was writing and speaking on the need to define the goal of nursing as a way of focusing the development of knowledge for practice. Dr. Roy had read a little about the concept of adaptation and was impressed with the resiliency of children she had cared for in pediatrics. At the first seminar in pediatric nursing, she proposed that the goal of nursing was promoting patient adaptation. Throughout her course work in the master's program Dorothy Johnson encouraged her to develop her concept of adaptation as a framework for nursing. The use of systems theory as defined by von Bertalanffy was an important early concept of the model, as was the work of Helson. Helson defined adaptation as a process of responding positively to environmental changes and described three types of stimuli, focal, contextual and residual. Dr. Roy made appropriate derivations of these concepts for use in describing situations of people in health and illness. Other authors that influenced the early development of the central concepts of the model included Dohrenwend, Lazarus, Mechanic, and Selye. The view of the person as an adaptive system took shape from this early work with the cognator and regulator being added as the major internal processes of the adapting person.