Unexpected discoveries and S-invention of design requirements: Important vehicles for a design process

Masaki Suwa, John Gero, Terry Purcell

Research output: Contribution to journalArticlepeer-review

254 Citations (Scopus)


Designers, during a conceptual design process, do not just synthesize solutions that satisfy initially given requirements, but also invent design issues or requirements that capture important aspects of the given problem. How do they do this? What becomes the impetus for the invention of important issues or requirements? So-called `unexpected discoveries', the acts of attending to visuo-spatial features in sketches which were not intended when they were drawn, are believed to contribute to it. The purpose of the present research is to verify this hypothesis. Analyzing the cognitive processes of a practising architect in a design session, we found that in about a half of his entire design process there were bi-directional relations between unexpected discoveries and the invention of issues or requirements. Not only did unexpected discoveries become the driving force for the invention of issues or requirements, but also the occurrence of invention, in turn, tended to cause new unexpected discoveries. This has provided empirical evidence for two anecdotal views of designing. First, designing is a situated act; designers invent design issues or requirements in a way situated in the environment in which they design. We call inventions of this sort situated-invention (S-invention). Secondly, a design process progresses in such a way that the problem-space and the solution-space co-evolve. Further, this has brought a pedagogical implication as well as an insight about an important aspect of learning by experience in design.

Original languageEnglish
Pages (from-to)539-567
Number of pages29
JournalDesign Studies
Issue number6
Publication statusPublished - 2000 Nov
Externally publishedYes

ASJC Scopus subject areas

  • Architecture
  • Arts and Humanities (miscellaneous)
  • General Engineering
  • General Social Sciences
  • Computer Science Applications
  • Artificial Intelligence


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