Lodestones and Leylines: Designing Locomotion in a Personal File System

We report on an exercise intended to help articulate constraints on locomotion and their implications for design. The assumption that locomotion is in service of navigation leads us to consider both cognitive and mechanical constraints. The exercise is to design support for accessing files in a hierarchical file system in the course of ordinary computer-based work. Characterizing the design situation in terms of four possible sources of locomotional constraints (the navigator, the task, the environment and the circumstances) leads to an abstract design of a dynamic locomotional mechanism that provides rapid accurate access to a small set of files. Applying this abstract design in Microsoft WindowsTM and Jazz yields two quite different specific designs. The exercise results in a broad organization of the factors that constrain locomotion into three categories: Locomotional mechanism, Navigational resources and Navigational effect.