Metaphors and models: Conceptual foundations of representations in interactive systems development

When system developers design a computer system (or other information artif act), they must inevitably make judgments as to how to abstract the worksys tem and how to represent this abstraction in their designs. In the past, su ch abstractions have been based either on a traditional philosophy of cogni tion or cognitive psychology or on intuitive, spontaneous philosophies. A n umber of recent developments in distributed cognition (Hutchins, 1995), act ivity theory (Nardi, 1996), and experientialism (Lakoff, 1987) have raised questions about the legitimacy of such philosophies. In this article, we di scuss from where the abstractions come that designers employ and how such a bstractions are related to the concepts that the users of these systems hav e. In particular, we use the theory of experientialism or experiential cogn ition as the foundation for our analysis. Experientialism (Lakoff, 1987) has previously only been applied to human-co mputer interaction (HCI) design in a quite limited way, yet it deals specif ically with issues concerned with categorization and concept formation. We show how the concept of metaphor, derived from experientialism, can be used to understand the strengths and weaknesses of alternative representations in HCI design, how it can highlight changes in the paradigm underlying repr esentations, and how it can be used to consider new approaches to HCI desig n. We also discuss the role that "mental spaces" have in forming new concep ts and designs.