Description of how a system changes its spatial or temporal organization or both over time. Consequently, it says nothing directly about the mechanism or mechanisms of change (e.g., in ontogenetic development). In dynamical systems terms, such a descriptor is referred to as an order parameter.
See Behavior mechanism, Biology, Child psychology, Cognitive psychology, Description, Developmental bootstrapping, Developmental outcomes, Descriptive explanation, Dynamical systems approaches, Mechanism, Microgenetic method, Model systems, Ontogenetic development, Order parameter, Proximal processes