The conceptual foundations of ecological interface design (EID) have been described in various places (Vicente & Rasmussen, 1990, 1992). Many evaluations have been performed of ecological interfaces against nonecological interfaces (Ham & Yoon, 2001; Reising, 1999; Sakuma, Itoh, Yoshikawa, & Monta, 1995; Vicente, Christoffersen, & Pereklita, 1995), and results suggest that EID is a promising approach to interface design for complex systems. However, relatively few descriptions exist of the mechanics of designing an ecological interface, and most of those focus on how information at different levels of an abstraction-decomposition space is mapped to computer screen real estate (Burns, 2000a, 2000b; Dinadis & Vicente, 1996, 1999). Only a few cases include a discussion of how the individual--and often configural--displays that constitute an ecological interface might be selected (Bennett, Nagy, & Flach, 1997; Hansen, 1995; Reising, 1999; Vicente, 1996).
Our goal in this paper is to provide some insight into how the individual display units of an ecological interface might be selected. We focus in particular on semantic mapping (Bennett & Flach, 1992), which is the process by which goal-relevant structures and relations in a work domain are mapped to visual forms that become the basis for an individual display. We first discuss the fundamental principles of EID and of configural display design, focusing especially on the semantic mapping process and three key ways it can be achieved. We then provide a structural and functional description of the Pasteurizer II microworld.
Following the recommendations of EID, we use work domain analysis to inventory the properties and relations that must be represented in an ecological interface for Pasteurizer II. In the main part of the paper we then outline the semantic mapping process for the various displays within the Pasteurizer II ecological interface, focusing particularly on the development of an energy display. We provide a brief report of a subjective evaluation of the configural displays within the Pasteurizer II ecological interface and an objective evaluation of the effectiveness of the ecological interface as a whole compared with a more conventional display. Finally, we draw from our experiences to outline the steps of an analytic process for using ELD.
In this paper we emphasize the distinction between configural displays and ecological interfaces--a distinction that is sometimes obscured. A configural display is a display unit that represents information about functionally related system components in a way that allows the operator to extract not only information about individual components at a local level but also higher-order information about relations between individual components at a more global level (Bennett, Toms, & Woods, 1993; Wickens & Carswell, 1995). In contrast, an ecological interface is a collection of display units, some of which may be configural displays, that together support the information needs of the human operator at various levels of abstraction and aggregation as formally identified in an abstraction-decomposition space (Vicente & Rasmussen, 1990, 1992). We therefore do not talk about ecological displays but, instead, about ecological interfaces and configural displays.
PRINCIPLES OF EID AND CONFIGURAL DISPLAY DESIGN
The ultimate objective of ELD is to provide operators with interfaces that allow them to more effectively engage in adaptive behavior if unanticipated or unexpected circumstances occur, thus making the overall human-machine system safer (Vicente & Rasmussen, 1990, 1992). EID is based on two sets of concepts: Rasmussen's abstraction hierarchy (Rasmussen, 1985) and the distinction among skill-, rule-, and knowledge-based behavior (Rasmussen, 1983). The abstraction hierarchy provides a framework for integrating structural and functional information about a work domain in a way that shows the means-ends relationships that are embodied in it. …