Preparation of this special issue was motivated by the First Workshop on Human-Computer Interaction with Mobile Devices, held at the University of Glasgow in May 1998. Drafts of some of the papers in this collection were presented at that workshop. The call for papers was later broadened to include additional material, and the normal review procedures and criteria of Transactions on Computer-Human Interaction (TOCHI) were used to select the final set of papers presented here.
Mobile computing systems, especially those connected via wireless networks, are beginning to transform the way we interact with computers, and they are likely to change the way we live. This development has largely been driven not by pre-existing user needs, but by advances in technology. However, once the technology is available, users demandindeed, expectthe new functions and facilities offered. It is safe to say that we still understand poorly the way that mobility affects user interaction. Part of the problem is that changes in the technology and its use are so rapid and so volatile that few consistent patterns have yet emerged. The immediate challenges to understanding and developing mobile interaction techniques and technologies are many, arising from the miniaturization of devices, the increased importance of context of use, and the variability of access to networked resources.
The papers in this special issue address some of the problems resulting from these trends and show the development of new ways of thinking about interaction with computer systems to account for the issues emerging from this fundamental shift in human-computer interaction. These new approaches promise to overcome some of the limitations we see in traditional, static, workstation-based forms of interaction. Some of the solutions involve applying new interaction techniques, such as alternative and multiple modes of interaction; others focus on developing flexible software architectures to encompass the demands made by mobile systems. Techniques that exploit the particularities of the context in which mobile devices are being used prevail in much of the work that is emerging and that is represented here.
Our goal as researchers in mobile interaction and interactive technologies is ultimately to be able to understand, identify, and describe the factors that are critical to successful design and, when possible, to be able to predict the effects of design decisions. However, it is also important to develop new interaction techniques and devices that fit better with mobile use. In the early stages of a new technology such as mobile systems, it can be difficult to untangle the exploration of new techniques from the search for understanding. By trying out new techniques and building new systems we are also creating test beds for observing the effects of the new technology and new settings. The papers presented here exhibit just these signs of early work: exploratory prototypes representing new interaction techniques, descriptive models that define a "design space," and informal qualitative evaluations.
In the first article, "Exploiting Space and Location as a Design Framework for Interactive Mobile Systems," Dix, Rodden, et al. focus on the context-sensitivity of mobile devices. They are concerned especially with supporting collaborative work and the distribution of devices in both physical and computational spaces. They produce a framework that structures the design space for developing a distributed computational platform to support the rapid development of applications within that framework.
In "Satchel: Providing Access to Any Document, Any Time, Anywhere," Lamming, Eldridge, et al. describe a new system for providing remote access to documents and a trial for evaluating it. They call this class of system a "document appliance." Features they have adopted to address the limitations of mobile devices include limiting functionality to only the minimal facilities necessary for the task at hand, using context-sensitive information to simplify user interaction, and using a document token-based protocol to minimize demands on bandwidth.
In "Nomadic Radio: Speech and Audio Interaction for Contextual Messaging in Nomadic Environments," Sawhney and Schmandt also focus on an application areain this case, access to messages and information services. Their approach is distinctive for its use of speech and voice to present information and to interact with the device. They describe a number of techniques to provide awareness of incoming messages with minimal intrusiveness; they too rely on context-sensitive techniques to minimize the burden on the user.
In "Improving Selection Performance on Pen-Based Systems: A Study of Pen-Based Interaction for Selection Tasks," Xiangshi Ren and Shinji Moriya investigate the use of pen-based interaction with mobile devices. They discuss two experiments that compare six pen-based selection strategies and associated state transition models for selecting targets on a small screen. They argue that current target selection strategies for pen-based systems are generally imitations of strategies used for mouse and touch-screen devices. They show that these strategies are probably not the most effective, especially when selecting small targets. (See interactions January-February 2001)
Finally, Pascoe, Ryan, and Morse, in "Using While Moving: HCI Issues in Fieldwork Environments," describe an application that has particularly demanding requirements for mobilitysupport for an ecological study recording the feeding patterns of giraffes in Kenya. As in most of the other papers, the authors discuss how to use context to reduce demands on user interaction. One distinction they identify, the "minimal attention user interface" (MAUI), is a trade-off between interaction steps and user attention.
Together, these papers represent an early focus on thinking about mobility and interaction. We can reasonably expect sufficient progress over the next few years, both in understanding and in enhanced technologies, that this special issue will seem quite dated in some respects. However, the main issues tackled (exploiting context, reducing interaction costs using inference and rich modalities, working with a diverse set of interaction modalities) will most probably remain central. In fact, the emphasis required by mobile-oriented HCI research on understanding and utilizing context and diverse interaction techniques is likely to have beneficial consequences for all interactive systems design in the future.
Co-edited by Allan MacLean (Xerox Research Centre Europe) and Philip Gray (University of Glasgow)
Figure. The Satchel system described by Lamming et al. People can pass each other document tokens using their mobile devices (bottom right). The token can then be used from the mobile device to print a copy of the document wherever it is required.
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