A systematic review of protocol studies on conceptual design cognition

This paper reports the first systematic review and synthesis of protocol studies on conceptual design cognition. 47 studies from the domains of architectural design, engineering design, and product design engineering were reviewed towards answering the following question: What is our current understanding of the cognitive processes involved in conceptual design tasks carried out by individual designers? Studies were found to reflect three viewpoints on the cognitive nature of designing: design as search; design as exploration; and design activities. Synthesising the findings of individual studies revealed ten categories of executive and non-executive function studied across the viewpoints: visual perception; mental imagery; semantic association; long term memory; working memory; selective attention; creative thinking; evaluation and decision making; externalisation; and reasoning and problem solving. The review highlights several avenues for future research, centering on the need for general formalisms, more objective methods to supplement protocol analysis, and a shared ontology of cognitive processes.