Decision Methods for Design: Insights from Psychology

This work aims at stimulating constructive conversation about decision methods in engineering design by using insights from psychology. I point out that any decision method has two components: coherence, which refers to internal consistency (do design choices satisfy a logical axiom?) and correspondence, which refers to external effectiveness (does a design concept satisfy a functional requirement?). Some researchers argue for “rational” methods such as multi-attribute utility theory, whereas others argue for “heuristics” such as the Pugh process, and the coherence/correspondence distinction can clarify this debate in two ways. First, by analyzing statements in the design literature, I argue that the debate is essentially about different strategies for achieving correspondence: Multi-attribute utility theory aims at achieving coherence with the expectation that coherence will imply correspondence, whereas the Pugh process aims at directly achieving correspondence. Second, I propose a new research question for design: “Under what conditions does achieving coherence imply achieving correspondence?”