Beth Yost

Beyond visual acuity: the perceptual scalability of information visualizations for large displays

The scalability of information visualizations has typically been limited by the number of available display pixels. As displays become larger, the scalability limit may shift away from the number of pixels and toward human perceptual abilities. This work explores the effect of using large, high resolution displays to scale up information visualizations beyond potential visual acuity limitations. Displays that are beyond visual acuity require physical navigation to see all of the pixels. Participants performed various information visualization tasks using display sizes with a sufficient number of pixels to be within, equal to, or beyond visual acuity. Results showed that performance on most tasks was more efficient and sometimes more accurate because of the additional data that could be displayed, despite the physical navigation that was required. Visualization design issues on large displays are also discussed.

Information visualization on large, high-resolution displays: issues, challenges, and opportunities

Larger, higher-resolution displays are becoming accessible to a greater number of users as display technologies decrease in cost and software for the displays improves. The additional pixels are especially useful for information visualization where scalability has typically been limited by the number of pixels available on a display. But how will visualizations for larger displays need to fundamentally differ from visualizations on desktop displays? Are the basic visualization design principles different? With this potentially new design paradigm comes questions such as whether the relative effectiveness of various graphical encodings are different on large displays, which visualizations and datasets benefit the most, and how interaction with visualizations on large, high-resolution displays will need to change. As we explore these possibilities, we shift away from the technical limitations of scalability imposed by traditional displays (e.g. number of pixels) to studying the human abilities that emerge when these limitations are removed. There is much potential for information visualizations to benefit from large, high-resolution displays, but this potential will only be realized through understanding the interaction between visualization design, perception, interaction techniques, and the display technology. In this paper we present critical design issues and outline some of the challenges and future opportunities for designing visualizations for large, high-resolution displays. We hope that these issues, challenges, and opportunities will provide guidance for future research in this area.

User Interaction with Scatterplots on Small Screens - A Comparative Evaluation of Geometric-Semantic Zoom and Fisheye Distortion

Existing information-visualization techniques that target small screens are usually limited to exploring a few hundred items. In this article we present a scatterplot tool for Personal Digital Assistants that allows the handling of many thousands of items. The applications scalability is achieved by incorporating two alternative interaction techniques: a geometric-semantic zoom that provides smooth transition between overview and detail, and a fisheye distortion that displays the focus and context regions of the scatterplot in a single view. A user study with 24 participants was conducted to compare the usability and efficiency of both techniques when searching a book database containing 7500 items. The study was run on a pen-driven Wacom board simulating a PDA interface. While the results showed no significant difference in task-completion times, a clear majority of 20 users preferred the fisheye view over the zoom interaction. In addition, other dependent variables such as user satisfaction and subjective rating of orientation and navigation support revealed a preference for the fisheye distortion. These findings partly contradict related research and indicate that, when using a small screen, users place higher value on the ability to preserve navigational context than they do on the ease of use of a simplistic, metaphor-based interaction style.Larger, higher resolution displays can be used to increase the scalability of information visualizations. But just how much can scalability increase using larger displays before hitting human perceptual or cognitive limits? Are the same visualization techniques that are good on a single monitor also the techniques that are best when they are scaled up using large, high-resolution displays? To answer these questions we performed a controlled experiment on user performance time, accuracy, and subjective workload when scaling up data quantity with different space-time-attribute visualizations using a large, tiled display. Twelve college students used small multiples, embedded bar matrices, and embedded time-series graphs either on a 2 megapixel (Mp) display or with data scaled up using a 32 Mp tiled display. Participants performed various overview and detail tasks on geospatially-referenced multidimensional time-series data. Results showed that current designs are perceptually scalable because they result in a decrease in task completion time when normalized per number of data attributes along with no decrease in accuracy. It appears that, for the visualizations selected for this study, the relative comparison between designs is generally consistent between display sizes. However, results also suggest that encoding is more important on a smaller display while spatial grouping is more important on a larger display. Some suggestions for designers are provided based on our experience designing visualizations for large displays

The Perceptual Scalability of Visualization

Larger, higher resolution displays can be used to increase the scalability of information visualizations. But just how much can scalability increase using larger displays before hitting human perceptual or cognitive limits? Are the same visualization techniques that are good on a single monitor also the techniques that are best when they are scaled up using large, high-resolution displays? To answer these questions we performed a controlled experiment on user performance time, accuracy, and subjective workload when scaling up data quantity with different space-time-attribute visualizations using a large, tiled display. Twelve college students used small multiples, embedded bar matrices, and embedded time-series graphs either on a 2 megapixel (Mp) display or with data scaled up using a 32 Mp tiled display. Participants performed various overview and detail tasks on geospatially-referenced multidimensional time-series data. Results showed that current designs are perceptually scalable because they result in a decrease in task completion time when normalized per number of data attributes along with no decrease in accuracy. It appears that, for the visualizations selected for this study, the relative comparison between designs is generally consistent between display sizes. However, results also suggest that encoding is more important on a smaller display while spatial grouping is more important on a larger display. Some suggestions for designers are provided based on our experience designing visualizations for large displays.

Shaping the Display of the Future: The Effects of Display Size and Curvature on User Performance and Insights

ABSTRACT As display technology continues to improve, there will be an increasing diversity in the available display form factors and scales. Empirical evaluation of how display attributes affect user perceptions and performance can help designers understand the strengths and weaknesses of different display forms, provide guidance for effectively designing multiple display environments, and offer initial evidence for developing theories of ubiquitous display. Although previous research has shown user performance benefits when tiling multiple monitors to increase the number of pixels, little research has analyzed the performance and behavioral impacts of the form factors of much larger, high-resolution displays. This article presents two experiments in which user performance was evaluated on a high-resolution (96 DPI), high pixel-count (approximately 32 million pixels) display for single-user scenarios in both flat and curved forms. We show that for geospatial visual analytics tasks there is a benefit to larger displays, and a distinct advantage to curving the display to make all portions of the display more accessible to the user. In addition, we found that changing the form factor of the display does have an impact on user perceptions that will have to be considered as new display environments are developed.

A multiple view approach to support common ground in distributed and synchronous geo-collaboration

In this paper we investigate strategies to support knowledge sharing in distributed, synchronous collaboration. Our goal is to propose, justify, and assess a multiple view approach to support common ground in geo-collaboration within multi-role teams. We argue that a collaborative workspace, which includes multiple role-specific views coordinated with a team view, affords a clear separation between role-specific and shared data, enables the team to filter out role-specific details and share strategic knowledge, and allows serendipitous learning about knowledge and expertise within the team. We discuss some key issues that need to be addressed when designing multiple views as a collaborative visualization. We illustrate the design features of a geo-collaborative prototype that address these issues in the context of two collaborative scenarios. We finally describe a laboratory method for investigating how multi-role teams establish common ground while the amount of prior shared knowledge and the type of visualization are experimentally manipulated.

Single complex glyphs versus multiple simple glyphs

Designers of information visualization systems have the choice to present information in a single integrated view or in multiple views. In practice, there is a continuum between the two strategies and designers must decide how much of each strategy to apply. Although high-level design guidelines (heuristics) are available, there are few low-level perceptual design guidelines for making this decision. We performed a controlled experiment with one, two, and four views to evaluate the strengths and weaknesses of these strategies on target detection and trend finding tasks in the context of multidimensional glyphs overlaid onto geographic maps. Results from the target detection tasks suggest that visual encoding is a more important factor when detecting a single attribute than the number of views. Additionally, for detecting two attributes, the trend indicates that reusing the most perceptually salient visual feature in multiple views provides faster performance than an integrated view that must map one of the attributes to a less salient feature.