Paul Baltes (1939 - 2006) provided together with his colleagues many of the main approaches to human development from a life-span perspective in a model that has influences a wide range of research, especially on adult development and aging. A key point in their model is that human development is complete and cannot be understood from a single discipline.
Four (4) key features of the life-span perspective were identified by Baltes and his colleagues, namely:
1. Multidirectionality - that development involves both growth and decline; as people grown in one area, they may lose in another at different rate. Example, people's vocabulary ability tends to increase throughout life, but reaction time tends to slow down.
2. Plasticity - a person's capacity is not pre-determined or carved in stone. Many skills can be learned or improved with practices, even in late life.
3. Historical context - each person develops within a particular set of circumstances determined by the historical time in which they are born and the culture in which they grow up. For example, living in a middle-class suburb is 1950's Indianapolits has little in common with living in a poor Latino neighborhood in 1990's in Texas.
4. Multiple causation this is how humans develop results from biological, psychological, socio-cultural, and life-cycle forces. For example, two (2) children growing up in the same family will have different experiences if one has a developmental disability and the other does not. Based on these principles, Baltes and colleagues (2006) proposed that life-span development consists of the dynamic interplay between growth, maintenance and loss regulation.