The Ecology of Human-Machine Systems II: Mediating 'Direct Perception' in Complex Work Domains

Abstract

Recently, a new class of artifacts has appeared in our environment: complex, high-technology work domains. An important characteristic of such systems is that their goal-relevant properties cannot be directly observed by the unaided eye. As a result, interface design is a ubiquitous problem in the design of these work environments. Nevertheless, the problem is one that has yet to be addressed in an adequate manner. An analogy to human perceptual mechanisms suggests that a smart instrument approach to interface design is needed to supplant the rote instrument (single-sensor-single-indicator) approach that has dominated to this point. Ecological interface design (ED) is a theoretical framework in the smart instrument vein that postulates a set of general, prescriptive principles for design. The goal of E D is twofold: first, to reveal the affordances of the work domain through the interface in such a way as to take advantage of the powerful capabilities of perception and action; and second, to provide the appropriate computer support for the comparatively more laborious process of problem solving. An example of the application of the E D framework is presented in the context of a thermal-hydraulic system. The various steps in the design process are illlustrated, showing how the abstract principles of E D can be applied in a prescriptive manner to develop a concrete design product. An important outcome of this discussion is the novel application of Rasmussen's (1985b) means-end hierarchy to structure the affordances of an ecosystem.