Anind K. Dey

Understanding and Using Context

Abstract: Context is a poorly used source of information in our computing environments. As a result, we have an impoverished understanding of what context is and how it can be used. In this paper, we provide an operational definition of context and discuss the different ways in which context can be used by context-aware applications. We also present the Context Toolkit, an architecture that supports the building of these context-aware applications. We discuss the features and abstractions in the toolkit that make the task of building applications easier. Finally, we introduce a new abstraction, a situation which we believe will provide additional support to application designers.

Towards a Better Understanding of Context and Context-Awareness

When humans talk with humans, they are able to use implicit situational information, or context, to increase the conversational bandwidth. Unfortunately, this ability to convey ideas does not transfer well to humans interacting with computers. In traditional interactive computing, users have an impoverished mechanism for providing input to computers. By improving the computer’s access to context, we increase the richness of communication in human-computer interaction and make it possible to produce more useful computational services. The use of context is increasingly important in the fields of handheld and ubiquitous computing, where the user?s context is changing rapidly. In this panel, we want to discuss some of the research challenges in understanding context and in developing context-aware applications.

A conceptual framework and a toolkit for supporting the rapid prototyping of context-aware applications

Computing devices and applications are now used beyond the desktop, in diverse environments, and this trend toward ubiquitous computing is accelerating. One challenge that remains in this emerging research field is the ability to enhance the behavior of any application by informing it of the context of its use. By context, we refer to any information that characterizes a situation related to the interaction between humans, applications, and the surrounding environment. Context-aware applications promise richer and easier interaction, but the current state of research in this field is still far removed from that vision. This is due to 3 main problems: (a) the notion of context is still ill defined, (b) there is a lack of conceptual models and methods to help drive the design of context-aware applications, and (c) no tools are available to jump-start the development of context-aware applications. In this anchor article, we address these 3 problems in turn. We first define context, identify categories of contextual information, and characterize context-aware application behavior. Though the full impact of context-aware computing requires understanding very subtle and high-level notions of context, we are focusing our efforts on the pieces of context that can be inferred automatically from sensors in a physical environment. We then present a conceptual framework that separates the acquisition and representation of context from the delivery and reaction to context by a context-aware application. We have built a toolkit, the Context Toolkit, that instantiates this conceptual framework and supports the rapid development of a rich space of context-aware applications. We illustrate the usefulness of the conceptual framework by describing a number of context-aware applications that have been prototyped using the Context Toolkit. We also demonstrate how such a framework can support the investigation of important research challenges in the area of context-aware computing.

The context toolkit: aiding the development of context-enabled applications

Context-enabled applications are just emerging and promisericher interaction by taking environmental context into account.However, they are difficult to build due to their distributednature and the use of unconventional sensors. The concepts oftoolkits and widget libraries in graphical user interfaces has beentremendously successtil, allowing programmers to leverage offexisting building blocks to build interactive systems more easily.We introduce the concept of context widgets that mediate betweenthe environment and the application in the same way graphicalwidgets mediate between the user and the application. We illustratethe concept of context widgets with the beginnings of a widgetlibrary we have developed for sensing presence, identity andactivity of people and things. We assess the success of ourapproach with two example context-enabled applications we havebuilt and an existing application to which we have addedcontext-sensing capabilities.

A stage-based model of personal informatics systems

People strive to obtain self-knowledge. A class of systems called personal informatics is appearing that help people collect and reflect on personal information. However, there is no comprehensive list of problems that users experience using these systems, and no guidance for making these systems more effective. To address this, we conducted surveys and interviews with people who collect and reflect on personal information. We derived a stage-based model of personal informatics systems composed of five stages (preparation, collection, integration, reflection, and action) and identified barriers in each of the stages. These stages have four essential properties: barriers cascade to later stages; they are iterative; they are user-driven and/or system-driven; and they are uni-faceted or multi-faceted. From these properties, we recommend that personal informatics systems should 1) be designed in a holistic manner across the stages; 2) allow iteration between stages; 3) apply an appropriate balance of automated technology and user control within each stage to facilitate the user experience; and 4) explore support for associating multiple facets of peoples lives to enrich the value of systems.

Heuristic evaluation of ambient displays

We present a technique for evaluating the usability and effectiveness of ambient displays. Ambient displays are abstract and aesthetic peripheral displays portraying non-critical information on the periphery of a users attention. Although many innovative displays have been published, little existing work has focused on their evaluation, in part because evaluation of ambient displays is difficult and costly. We adapted a low-cost evaluation technique, heuristic evaluation, for use with ambient displays. With the help of ambient display designers, we defined a modified set of heuristics. We compared the performance of Nielsens heuristics and our heuristics on two ambient displays. Evaluators using our heuristics found more, severe problems than evaluators using Nielsens heuristics. Additionally, when using our heuristics, 3-5 evaluators were able to identify 40--60% of known usability issues. This implies that heuristic evaluation is an effective technique for identifying usability issues with ambient displays.

CybreMinder: A Context-Aware System for Supporting Reminders

Current tools do not provide adequate support to users for handling reminders. The main reason for this is the lack of use of rich context that specifies when a reminder should be presented to its recipient. We describe Cybre-Minder, a prototype context-aware tool that supports users in sending and receiving reminders that can be associated to richly described situations involving time, place and more sophisticated pieces of context. These situations better define when reminders should be delivered, enhancing our ability to deal with them more effectively. We describe how the tool is used and how it was developed using our previously developed Context Toolkit infrastructure for context-aware computing.

The Conference Assistant: combining context-awareness with wearable computing

We describe the Conference Assistant, a prototype mobile, context-aware application that assists conference attendees. We discuss the strong relationship between context-awareness and wearable computing and apply this relationship in the Conference Assistant. The application uses a wide variety of contexts and enhances user interactions with both the environment and other users. We describe how the application is used and the context-aware architecture on which it is based.

A Context-Based Infrastructure for Smart Environments

In order for a smart environment to provide services to its occupants, it must be able to detect its current state or context and determine what actions to take based on the context. We discuss the requirements for dealing with context in a smart environment and present a software infrastructure solution we have designed and implemented to help application designers build intelligent services and applications more easily. We describe the benefits of our infrastructure through applications that we have built.

Personal privacy through understanding and action: five pitfalls for designers

To participate in meaningful privacy practice in the context of technical systems, people require opportunities to understand the extent of the systems’ alignment with relevant practice and to conduct discernible social action through intuitive or sensible engagement with the system. It is a significant challenge to design for such understanding and action through the feedback and control mechanisms of today’s devices. To help designers meet this challenge, we describe five pitfalls to beware when designing interactive systems—on or off the desktop—with personal privacy implications. These pitfalls are: (1) obscuring potential information flow, (2) obscuring actual information flow, (3) emphasizing configuration over action, (4) lacking coarse-grained control, and (5) inhibiting existing practice. They are based on a review of the literature, on analyses of existing privacy-affecting systems, and on our own experiences in designing a prototypical user interface for managing privacy in ubiquitous computing. We illustrate how some existing research and commercial systems—our prototype included—fall into these pitfalls and how some avoid them. We suggest that privacy-affecting systems that heed these pitfalls can help users appropriate and engage them in alignment with relevant privacy practice.