In Part One, developmental psychology was briefly defined to illus-
trate the unique features of a developmental approach to the study of behavior.
The dominant focus of this approach is on describing, explaining, and modify-
ing (optimizing) patterns of intraindividual change in behavior and inter-
individual differences in such change characteristics. A methodology for the
study of behavioral development deals with the principles and strategies
involved in the pursuit of knowledge about the ways individuals change
with time.

Any methodology has at least two aspects. The first concerns issues
of the empirical method in general. The nature of knowledge, the nature of the
scientific method, and the strategies of theory construction and hypothesis
testing are examples of such general issues of methodology. The second aspect
of methodology is unique to the subject matter concerned. In our case, it is
specific to developmental psychology. Examples of development-specific
methodology are techniques developed to observe infant activity and social-
interaction patterns in the elderly, or data-analysis models formulated to
quantify and structure behavioral change along multiple dimensions. Compar-
ing the use of cross-sectional designs with the use of longitudinal designs is
another problem characteristic of development-specific methodology.

The chapters in Part Two provide an overview of general aspects of
design methodolog). Occasionally, we will show how issues of general meth-
odology apply to the study of development, particularly when questions of
measurement and the interplay between theory and methodology are dis-
cussed. The use of the term development is a good case in point. Various views
of the term lead to distinct ways of operationalizing research questions,
interpreting data, and building theories.

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