Three Guiding Propositions
These propositions emphasize conceptual and methodological issues in the study of lifespan behavioral development, and thereby provide a general script for formulating research questions in more specific domains of interest.
For more than three decades, the Center for Lifespan Psychology has promoted a perspective on behavioral development that seeks to integrate age periods, domains of functioning, timescales, and levels of analysis. In part, through these efforts, lifespan psychology has evolved into a distinct conceptual approach within developmental psychology. The Center’s current research agenda can be summarized by three interrelated theoretical propositions that reflect this tradition. In line with the general tenets of lifespan psychology, these propositions emphasize conceptual and methodological issues in the study of lifespan behavioral development, and thereby provide a general script for formulating research questions in more specific domains of interest.
Study lifespan changes in behavior as interactions among maturation, learning, and senescence
Maturation, senescence, and learning mutually enrich and constrain each other throughout the lifespan and must be understood and studied as interacting forces driving the brain–behavior–environment system. In this endeavor, psychologists occupy a central position because they possess a rich and adequate repertoire of experimental and methodological tools to describe and modify the organization of behavior.
Lifespan research theory and methods: Integration across domains, timescales, and levels of analysis
Developmental psychology is faced with three difficult integrative tasks. First, there is the need to integrate theorizing and research practice across functional domains to attain a comprehensive picture of individual development. Second, there is a need to understand the mechanisms that link short-term variations to long-term change. Short-term variations are often reversible and transient, whereas long-term changes are often cumulative, progressive, and permanent. Establishing links between short-term variations and long-term changes is of eminent heuristic value, as it helps to identify mechanisms that drive development into different directions. Third, to arrive at mechanistic explanations of behavioral change, there is the need to integrate behavioral and neuronal levels of analysis. In short, developmental psychology requires theory and methodology apt to integrate (a) multiple domains of functioning, (b) multiple timescales, and (c) multiple levels of analysis.
Exploration of age-graded differences in behavioral plasticity to identify mechanisms of development
Behavioral plasticity, or the alteration of developmental trajectories through experience, is a precious phenomenon. Scientifically, inquiries into the plasticity of human behavior are a rich source of developmental information. Through the assessment of “changes in change,” they offer the promise to observe the operation and proximal consequences of developmental mechanisms. In particular, cognitive intervention studies, in which research participants of different ages are instructed and trained to perform one or more cognitive tasks, come with important validity benefits, such as (a) an increase in experimental control, (b) the identification of age differences near asymptotic performance levels, and (c) the assessment of transfer and maintenance effects. If neurochemical, neuroanatomical, or neurofunctional imaging measures are assessed before, during, and after training, intervention studies also offer new insights into relations between behavioral and neuronal levels of plasticity. Thus, by partly taking control over behavior–environment interactions, the mechanisms of learning can be studied in the context of maturation and senescence. When longitudinal information is available, intervention studies bridge the gap between short-term alterations in performance and long-term developmental trajectories.