The paper reviews protocol and other empirical studies of design activity, and summarises results relevant to understanding the nature of design cognition from an interdisciplinary, domain-independent overview. Results are presented in three major aspects of design cognition - the formulation of problems, the generation of solutions, and the utilisation of design process strategies. Parallels and comparisons between results are drawn, and a number of issues identified. Many similarities of design cognition across domains of professional practice are found. It seems that the ‘intuitive’ behavior of experienced designers is often highly appropriate to design tasks, although appearing to be ‘unprincipled’ in theory
