Roy's work is a conceptual model that views the individual as an adaptive system that is a biopsychosocial being required to adapt to environmental stimuli.
Adaptation is considered to take place in one biological and three psychosocial modes.
The physical self deals with body sensation and body image. The four modes are interrelated. Responses in any one mode may have an effect on or act as a stimulus on one or all of the other modes. Environmental stimuli are categorized as focal, contextual, or residual. When the factors making up residual stimuli become known, they are considered contextual stimuli.