Dugald Hutchings, John Stasko, Mary Czerwinski
The term Distributed Display Environment (DDE) compactly describes computer systems that present output to more than one physical display. Often DDEs allow attached input devices to treat the displays as a contiguous surface but this is not necessarily a requirement. Examples include multiple-monitor desktop systems, rooms with networked projectors and displays showing information on any physical surface, or even campus- or city-wide connected information display systems. In any of these physical configurations, there can be a single user, collaborative user groups, or multiple users in non-collaborative situations.
Although much previous HCI research includes implicit or explicit assumptions that a computer system has at most one physical display attached, recent research has recognized that a computer system can have more than one physical display and that people frequently use multiple displays much differently than single-display systems. Research methods and foci have varied, but findings suggest that (1) continuing to define the relevant aspects of DDEs is worthwhile due to obvious and quantifiable benefits of these environments and (2) there are important aspects of interfaces that have been ignored in the past because of the assumption of a single-display output model.
In April 2005 at the CHI conference in Portland, 16 researchers gathered at the Distributed Display Environment workshop to discuss the future of the field. The organizers structured the workshop to encourage discussion of future directions of the field. In particular, only the first 90 minutes covered participants' past work in the area while the remaining five hours were devoted to discussing four specific goals: (1) determine promising areas for new interaction research, (2) detail the aspects of incorporating passive information display into interfaces, (3) determining what to evaluate and how to evaluate it, and (4) outline broader implications of the increasing ubiquity of DDEs to HCI research. While the group discussion did address each of these goals in some way, the researchers became more interested in crafting a first draft of a framework of the many factors that DDE research involves. This interest seems to primarily arise from the wide variety of work that was presented by each researcher in those first 90 minutes; there was a clear desire to build a common language to facilitate a shared understanding of each other's work. As a result, the group devoted most of the time to brainstorming and generating an initial framework, with frequent pauses for discussion when suggested framework elements needed deeper interpretation or explanation.
We now share a selection of framework elements that directly address the multi-display system properties. Note that some very interesting aspects of the framework do not involve properties of the display system at all, such as whether it supports multiple users simultaneously or only a single user at one time, but since these are thoroughly discussed in other forums we leave them aside in this brief article.
One element of the framework is the degree to which an interface supports replication, i.e. showing the same information or UI components on multiple displays simultaneously. The notion that replication can be useful is beginning to appear more frequently and for a variety of situations, such as for personal use in single-user multiple-monitor interface situations , mixed use of personal displays and group-shared displays , mixed use of wall-size displays [4, 1], or critical display environments such as the operating room . One research group has even started to develop general-purpose replication interfaces . Replication can ease the burden of input-device navigation or even physical movement of the eyes or body and the additional display space offered by distributed displays raises questions of how, where, and when replication will be appropriate and effective.
Another element of the framework is the usability of the distributed display environment itself, not necessarily the interfaces used to interact with information in it. Is the relationship of the displays observable, i.e. is there some way that users can discover how the display devices relate to one another? Is the display system dynamic? In particular, in situations of either single-user or co-located collaborative use, how easily and to what degree can users alter the logical configuration of the displays to reflect any physical alterations of the DDE? Is the display system scalable both in the sense that the quantity of displays can be increased and that the variety of displays can be expanded? Dynamicity and scalability are of particular interest since "[multiple displays] are invariably popular with those who try them" .
A final element of the framework relates to evaluating interfaces designed to be used in a distributed display environment. Does "large environment" evaluation address a large pixel-space (number of pixels available to a user), a large physical space (actual distances between displays), or both? Low-fidelity prototyping may provide clues as to how build DDE systems and interfaces, but there is a question as to how well low-fidelity prototypes can generalize to hi-fidelity implementations since many participants may have no exposure to a DDE. Furthermore, the notion that many DDE experiments will involve heterogeneous populations of participants presents questions such as whether there will be a necessary adjustment period during which participants may be less effective in completing tasks followed by a period in which they improve. In other words, participant exposure time may be a key factor in collecting trustworthy experimental data, as well as in providing clues as to how steep of a "learning curve" may be involved in effectively using a DDE. As with all other areas of HCI, researchers may decide to pause to reexamine whether tried-and-true techniques implicitly assume a single display channel.
The three topics that we have addressed should give the reader a taste of the discussion that researchers in the DDE area engaged in at the workshop. We hope to continue to improve the draft of the framework and publish it in a more formal setting. At the conclusion of the workshop the group proposed a number of additional and supplemental steps in order to push the field forward as well as widen the number of researchers taking notice. There are interests in building a set of benchmark tasks so that differing DDE systems can be effectively compared and contrasted and in making toolkits and interfaces widely available so that other researchers can more easily conduct research in the area. For more information about the workshop, please visit www.cc.gatech.edu/~hutch/dde.
Dugald Ralph Hutchings
Georgia Institute of Technology
Georgia Institute of Technology
Mark Ashdown, Brian P. Bailey, Blaine Bell, Jacob T. Biehl, Mary Czerwinski, Katherine Everitt, Steven Feiner, Duke Hutchings, Kori M. Inkpen, Gerd Kortuem, Benoit Mansoux, Laurence Nigay, Kathy Ryall, Chia Shen, John Stasko, Wolfgang Stuerzlinger.
About the Authors:
Duke Hutchings is a PhD candidate in John Stasko's Information Interfaces research group and has held two internships with Mary Czerwinski's Visualization and Interaction research group at Microsoft Research. His work with those groups focuses on window management issues for multiple-monitor systems. More information is available at www.cc.gatech.edu/~hutch.
John Stasko is a professor in the College of Computing and the GVU Center at the Georgia Institute of Technology, where he is director of the Information Interfaces Research Group (www.cc.gatech.edu/gvu/ii). His research is in the area of information visualization, peripheral awareness of information, and software agents.
Mary Czerwinski is a senior researcher with Microsoft Research where she is manager of the Visualization and Interaction Research group (http://research.microsoft.com/vibe). Her primary research areas include spatial cognition, information visualization, and task switching.
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