We provide an introduction to the essential constructs involved in dyn
amic modeling. These constructs are then related to issues in psycholo
gical development. In particular, we discuss stages, states, sequences
, and pure transition models as well as cross-sectional and longitudin
al experimental designs. We conclude that transition is a key invarian
ce in development and that single subject, longitudinal designs are es
sential in studying the dynamics of ontogeny. (C) 1994 Academic Press,
Inc.