The integration of the different disciplines of gerontology can be promoted by pointing to the analogies in biological, medical, psychological, and sociological constructs and theories of aging. Max Bürger's construct of "biomorphosis", the functional age approach in physiology, and the principle of homeostasis can contribute to the formulation of hypotheses and theories in the behavioral and social sciences, too. A common frame of reference for this integrated interdisciplinary gerontology is a differential approach which tries to define different patterns of aging, their biological, clinical, social, and psychological conditions, the control and prediction of the aging process within the frame-work of these patterns and the prevention of adverse patterns. An important contribution of behavioral sciences to this differential gerontological is defined by cognitive theories of behavior which point to the decisive role of the perceived (vs. the "objective") situation in selection of responses of the aged.