The term "tropism" refers to the growth characteristics exercised by organisms under the influence of external forces. Contextualizing his argument in biology, aesthetics and literature, Ton Verstegen applies this figure to those architectures in which movement and dynamics play a central role. Verstegen argues that spatial animation always entails metaphoric or conceptual animation, providing examples from a variety of architects and demonstrating how computer technologies in design have affected the possibilities of movement in architecture.