ABSTRACT
This chapter presents a psychological analysis of the ways in which designers bridge the gap between an understanding of existing artifacts and the synthesis of new artifacts. We propose a taxonomy of design reasoning, five distinct ways of bringing psychological constraints to bear on the design process: assessing an artifact genre, hillclimbing from a predecessor artifact, process modeling, scenario envisionment, and formative evaluation. We explore how these modes of reasoning complement one another and how their unique contributions can be integrated through design rationale. In a case study exploring the interaction of the modes, we construct a psychological design rationale for a key component of an intelligent tutoring system for Smalltalk, a system-generated display of user goals called the Goalposter.
