Formality Considered Harmful: Experiences, Emerging Themes, and Directions on the Use of Formal Representations in Interactive Systems

Abstract

This paper reflects on experiences designing, developing, and working with users of a variety of interactive computer systems. The authors propose, based on these experiences, that the cause of a number of unexpected difficulties in human-computer interaction lies in users' unwillingness or inability to make structure, content, or procedures explicit. Besides recounting experiences with system use, this paper discusses why users reject or circumvent formalisms which require such explicit expression, and suggests how system designers can anticipate and compensate for problems users have in making implicit aspects of their tasks explicit. The authors propose computational approaches that address this problem, including incremental and system-assisted formalization mechanisms and methods for recognizing and using undeclared structure; they also propose non-computational solutions that involve designers and users reaching a shared understanding of the task situation and the methods that motivate the formalisms. This paper poses that, while it is impossible to remove all formalisms from computing systems, system designers need to match the level of formal expression entailed with the goals and situation of the users -- a design criteria not commonly mentioned in current interface design.