(Baltes, 1987) states that Life-span developmental psychology is the field of psychology, thst describes human behavior across from conception to death. he describes life span as being a study constancy and change in behavior throughout the life course from conception to death. The goal of this study is to further our knowledge about how development changesover the entire life. developing a knowledge of the general principles of development and the differences and similarities in development across individuals. -Appling the developmental theory presented in Baltes’s set of six principles that define our understanding of human devemoment.Baltes (1987) give a set of principles which guide the study of human development within a life-span.
