Communication-minded visualization: a call to action.

Visualization applications can enable interactions between people in powerful and unexpected ways, as illustrated by the following two personal experiences.

In the spring of 2003, the first author created PostHistory, an application to visualize e-mail archives of individuals. (1) Given the personal nature of the data, it was assumed the archive owner would view the data alone. Indeed, during a usability study, the experimenters carefully explained to participants that no one other than the owner would have access to the visualizations. Yet, as soon as users had access to the application, they began finding ways to share the resulting images. Users mailed screen captures to friends and family; they invited colleagues to sit with them to view the screen images together. This sharing triggered deep reminiscing and long conversations about events in their lives, which the users considered an important benefit of the visualization system.

In the winter of 2005, the second author created NameVoyager, a Web-based visualization of historical data on baby name popularity. (2) NameVoyager helps expectant parents find names for their babies and encourages individual exploration of the baby name data. As it turned out, the data was explored, but not just in isolation. Thousands of visitors to the site engaged in conversations about their findings, using discussion forums and blog comments, collectively identifying trends and anomalies and forming conjectures about the data.

Although not specifically designed for communication, the preceding applications created rich opportunities for users to engage in discussions about the data being displayed. Inspired by these experiences, in this paper we introduce the concept of communication-minded visualization (CMV), a visualization designed to support communication and collaborative analysis. Our emphasis is on the design of the user experience rather than the technical implementation challenges.

We believe that designing for communication is essential because users do not interact with visualizations solely to gain personal insights. An insight that matters usually has to be communicated to others. (3) As Johnson et al. point out, (4) visualization plays an important role in many disciplines, such as biology, physics, and genetics. To harness the power of visualization as a working tool for multidisciplinary teams, designers need to pay close attention to how visualization affects and enables the communication of discoveries and the discussion of ideas within multiple contexts.

As in the preceding examples, communication of visualization findings can take place in a variety of ways, ranging from the pervasive screen capture to elaborate narrated videos. Also ubiquitous is the practice of leaning over someone's shoulder to see what is happening on his or her monitor. It is not uncommon to have up to six viewers looking at the same visualization screen as one person interacts with the data. (5) In business meetings screen captures or videos are projected on a large screen. In presentations to professional conferences video sequences have become more common as a way of making interaction and transition techniques easily understandable to viewers. Finally, printouts are used to share analysis and findings.

The process involved in sharing the visualization data is often cumbersome, including screen captures, an image-editing program, and an e-mail program. There seems to be a gap between the visualization application and the sharing process. Current visualization platforms lack support for communicating a user's findings.

Aside from the fact that communication and sharing capabilities are often external to visualization systems, most ad hoc sharing practices suffer from other drawbacks as well. They often rely on interactions that are not very effective in screen capture or printed form. For example, many popular visualizations, such as Map of the Market from SmartMoney, (6) use tooltips--small windows that contain explanatory text when the mouse moves over a target--which are lost in screen capture form. For three-dimensional visual applications, removing the motion element from the user interface means that the viewer loses one of the strongest depth cues. (7) Videos of an interactive computer session can be hard to follow if the viewer has no advance warning regarding the part of the screen where the keyboard or mouse actions take place. Aside from basic legibility problems of screen captures and printouts, an inability to interact with the application (which applies to canned video as well) may reduce the credibility of an analysis. As a result, ad hoc sharing of noninteractive versions of a visualization is not a satisfactory solution.

Although visualization-driven communication abounds in the real world and although some commercial products have started to explore CMV-style interaction, capturing and communicating visualization interaction and discovery processes have received little attention from the research community. In this paper we propose a conceptual framework within which to pursue CMV issues, and we hope this framework will help ground inquiry in this area as well as encourage the emergence of a community of interest. We lay out the range of issues in the area, associate this topic to related research areas, and provide initial guidelines for CMV design and evaluation.

The rest of this paper is organized as follows. First, we describe a number of commercial and experimental visualization systems that address various communication needs. Second, we highlight established research areas whose concerns are related to those in CMV. We point out the relevant topics in these areas and how these issues emerge in CMV. Finally, we outline proposals for the design and evaluation of CMV applications.

EXISTING VISUALIZATION SYSTEMS

Designers of visualization systems have not completely ignored the role of communication and group sharing. We describe here a number of commercial and experimental visualization systems that have been designed with communication in mind.

One such system is CoMotion **, a commercially available product from Maya Viz, LLC. that allows users to synchronously and remotely jointly perform visual data analysis tasks. In CoMotion each user opens a window that provides a common view of the visualization target. Users take turns interacting with the data in the shared view, chatting by means of instant messaging.

The CoMotion architecture led to Command Post of the Future, an application for the United States military that allows the members of a command unit to share information through a collaborative visualization application. All users are located in a command room in which a large visualization screen is the focal point. In addition, users have individual machines running a copy of the visualization application, and the information they generate--manipulations and annotations of maps--shows up at once on all other users' screens. In 2004, the system was deployed in the field, and military personnel credit the application with providing troops with the highest level of insight and situational awareness they had ever experienced. (8)

Since the mid-1990s, several research projects have explored synchronous remote sharing of scientific visualizations under the rubric of "collaborative visualization." (9) Collaborative visualization systems have become important data exploration tools in a range of scientific fields from medical diagnosis (10) to archaeological excavations. (11) The concerns of this field have primarily been related to the technical problem of faithfully replicating one user's experience for another at a different network location. Brodlie et al. (12) provide an excellent survey of the state of the art.

Visualization sharing can also happen asynchronously. DecisionSite ** Posters from Spotfire, Inc. has been designed specifically to support asynchronous sharing of visualizations. The application is a Web-based client that allows users to capture interactive snapshots of analyses and pass them as posters to a co-worker, who in turn can refine the analysis. Users can make notes and set visualization "bookmarks" (pointers to a specific state of the visualization). The notes have associated threads and allow any researcher to see comments made by others. DecisionSite Posters can also be sent using regular e-mail; a recipient of a poster may then view and interact with the poster with a Web browser and even follow the sequence of steps taken by the sender.

DecisionSite Posters was launched in January of 2002 and has seen a slow but steady rate of adoption. According to the company, the product was created in response to customer interest in sharing and collaboration. (5) So far, the communication capabilities in DecisionSite Posters have been used in an unexpected way. Instead of engaging in deeply nested threaded conversations by using the conversation panel, as envisioned by the designers of the system, users have largely used the tool just for presenting their findings to colleagues. The ability to create commentary associated with pointers into the visualization provides an easy way to choreograph a step-by-step presentation. Having such paths coupled with the full-fledged visualization makes it easy for viewers to take advantage of the directed view of the data and at the same time break off, when desired, to freely explore the visualization.