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The following paper provides an assessment of how selected properties of a virtual reality system impact size-distance judgments in a virtual environment. Manipulations are made in viewing conditions (biocular vs. stereoscopic), image resolution, field of view, scene contrast, and target distance, while subjects attempt to match the attributes of a comparison object with a standard object. General findings suggest that under more natural viewing conditions, size-distance judgments in virtual environments differ from those found previously in physical environments; whereas, under impoverished conditions, performance differences between the two environments are similar.systems. Each nomograph produces a design trade-off space that reveals ways to make a VR system which achieves a predicted level of human performance in the virtual environment. One aim of our group is to produce design trade-off nomographs of this nature.

This report has been reviewed by the Office of Public Affairs (PA) and is releasable to the National Technical Information Service (NTIS). At NTIS, it will be available to the general public, including foreign nations. This technical report has been reviewed and is approved for publication.

Work domain analysis (WDA) is an approach developed by Rasmussen (1985) for representing the structure of complex work environments. Many examples of the approach have surfaced in the literature, predominantly of physically coupled causal systems (e.g., process control). For causal systems, the environment is strongly constrained by the laws of nature. This approach can also be used for representing intentional systems (e.g., military command and control), although there is some controversy on this issue. For intentional systems, the environment is strongly constrained by actors' intentions, values, and priorities of practice. This paper discusses the differences between causal and intentional systems and provides direction on how to proceed with a WDA for intentional systems. A WDA is presented for emergency ambulance dispatch management and military command and control to illustrate the approach. Finally, a discussion of the implications and future research recommendations are presented.

We have been developing user interface clients as fully integrated support systems. A Work Centered Support System aids work by using direct and indirect, passive and active methods. An important property of WCSS systems is the use of form representations as passive devices to help reduce work complexity while simultaneously aid users in adaptive problem solving. Based on our experience implementing the design of three WCSSs we have distilled a set of three form-based design principles that help insure a work-centered perspective is expressed in the interface and that aid problem solving. These principles connect problem-solving objects with work domain objects at different levels of abstraction, utilize a first-person work ontology, and organize information selection and layout based on problem relationships. This paper describes the principles and uses illustrations from our designs to indicate how they reduce work complexity.

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In the naturalistic decision-making literature, intuitive cognition is at the heart of a pattern recognitionbased decision model called the recognition-primed decision model. Given the importance of intuitive cognition in naturalistic decision-making theory, we explore the question of what makes intuitive cognition effective for decision making and, in so doing, present an extended empirical and theoretical foundation for the intuitive component in naturalistic decision making. We theorize that intuitive cognition is effective because it (1) possesses a capability for grounded, situational meaning making (sign interpretation); (2) is operative over extended work intervals involving interruptions; and (3) is instrumental in handling situated complexities of everyday living. Other characteristics of intuitive cognition and its foundations are discussed. We propose that intuitive cognition represents the core of cognition-grounded, situational meaning making-whereas analytical cognition represents a form of an intellectual exoskeleton that provides added capabilities (e.g., working memory).

Information superiority is a strategic goal of the US Air Force. To achieve this goal the Air Force aims to produce a battlespace infosphere that will provide an unprecedented degree of connectivity and availability of raw data and value-added information for warfighter use. The AbstractInformation superiority is a strategic goal of the US Air Force. To achieve this goal the Air Force aims to produce a battlespace infosphere that will provide an unprecedented degree of connectivity and availability of raw data and value-added information for warfighter use. The essential challenge of the infosphere is to be able to provide the right information, at the right time, in the right form to enable warfighters to take effective, coordinated action. Although the infosphereÕs core web and agent technologies are clearly able to provide a heterogeneous infosphere, improved interface technologies are also needed to address problems of information overload and how to provide support to specific end-users without the support tools themselves becoming an impediment to task performance. We have developed a prototype WorkCentered Support System software client as a means to address these interface issues. The WCSS approach achieves effective support in a software agent environment by blending direct manipulation, work field organization, and decision, collaborative, and product development aiding in a manner that is tailored to both formal and informal characteristics of user work. In this paper we describe the philosophy behind and characteristics of the WCSS technology. We illustrate the technology with a discussion of an interactive WCSS prototype designed to improve support to military airlift mission planners at the headquarter level.