The size of human fingers and the lack of sensing precision can make precise touch screen interactions difficult. We present a set of five techniques, called Dual Finger Selections, which leverage the recent development of multitouch sensitive displays to help users select very small targets. These techniques facilitate pixel-accurate targeting by adjusting the control-display ratio with a secondary finger while the primary finger controls the movement of the cursor. We also contribute a “clicking ” technique, called SimPress, which reduces motion errors during clicking and allows us to simulate a hover state on devices unable to sense proximity. We implemented our techniques on a multi-touch tabletop prototype that offers computer visionbased tracking. In our formal user study, we tested the performance of our three most promising techniques (Stretch, X-Menu, and Slider) against our baseline (Offset), on four target sizes and three input noise levels. All three chosen techniques outperformed the control technique in terms of error rate reduction and were preferred by our participants, with Stretch being the overall performance and preference winner. Author Keywords Touch screens, tabletop displays, two-finger, bi-manual,

Retrieving the stylus of a pen-based device takes time and requires a second hand. Especially for short intermittent interactions many users therefore choose to use their bare fingers. Although convenient, this increases targeting times and error rates. We argue that the main reasons are the occlusion of the target by the user’s finger and ambiguity about which part of the finger defines the selection point. We propose a pointing technique we call Shift that is designed to address these issues. When the user touches the screen, Shift creates a callout showing a copy of the occluded screen area and places it in a non-occluded location. The callout also shows a pointer representing the selection point of the finger. Using this visual feedback, users guide the pointer into the target by moving their finger on the screen surface and commit the target acquisition by lifting the finger. Unlike existing techniques, Shift is only invoked when necessary—over large targets no callout is created and users enjoy the full performance of an unaltered touch screen. We report the results of a user study showing that with Shift participants can select small targets with much lower error rates than an unaided touch screen and that Shift is faster than Offset Cursor for larger targets. Author Keywords mobile devices, touch-screens, interaction techniques, occlusion,

High precision parameter manipulation tasks typically require adjustment of the scale of manipulation in addition to the parameter itself. This paper introduces the notion of Zoom Sliding, or Zliding, for fluid integrated manipulation of scale (zooming) via pressure input while parameter manipulation within that scale is achieved via x-y cursor movement (sliding). We also present the Zlider (Figure 1), a widget that instantiates the Zliding concept. We experimentally evaluate three different input techniques for use with the Zlider in conjunction with a stylus for x-y cursor positioning, in a high accuracy zoom and select task. Our results marginally favor the stylus with integrated isometric pressure sensing tip over bimanual techniques which separate zooming and sliding controls over the two hands. We discuss the implications of our results and present further designs that make use of Zliding.

Selecting a menu item in a cascading pull-down menu is a frequent but time consuming and complex GUI task. This paper describes an approach aimed to support the user during selection in cascading pull-down menus when using an indirect pointing device. By enhancing such a cascading pulldown menu with “force fields”, the cursor is attracted toward a certain direction, e.g. toward the right hand side within a menu item, which opens up a sub-menu, making the cursor steering task easier and faster. The experiment described here shows that the force fields can decrease selection times, on average by 18%, when a mouse, a track point, or touch pad is used as input device. The results also suggest that selection times in cascading pull-down menus can be modeled using a combination of Fitts ’ law and the steering law. The proposed model proved to hold for all three devices, in both standard and in enhanced cascading pull-down menus, with correlations better than r² = 0.90.

Twenty years after the general adoption of overlapping windows and the desktop metaphor, modern window systems differ mainly in minor details such as window decorations or mouse and keyboard bindings. While a number of innovative window management techniques have been proposed, few of them have been evaluated and fewer have made their way into real systems. We believe that one reason for this is that most of the proposed techniques have been designed using a low fidelity approach and were never made properly available. In this paper, we present Metisse, a fully functional window system specifically created to facilitate the design, the implementation and the evaluation of innovative window management techniques. We describe the architecture of the system, some of its implementation details and present several examples that illustrate its potential.

As noted almost a decade ago, HCI (Human-Computer Interaction) aspects of visual language environments are under-developed. This remains a fact, in spite of the central role played by user interfaces in the acceptance and usability of visual languages. We introduce ZVTM, a toolkit aimed at promoting the development of HCI aspects of visual environments by making the creation of interactive structured graphical editors easier, while favoring the rapid integration of novel interaction techniques such as zoomable user interfaces, distortion lenses, superimposed layers, and alternate scrolling and pointing methods. 1.

This paper first presents an empirical study involving selection of isolated expanding targets, with the goal of determining how to predictively model performance. Various factors, such as the time at which expansion occurs, are varied to investigate their influence on performance

On wall-size displays with pen or touch input, users can have difficulties reaching display contents located too high, too low, or too far away. Drag-and-drop interactions can be further complicated by bezels separating individual display units. Researchers have proposed a variety of interaction techniques to address this issue, such as extending the user's reach (e.g., push-andthrow) and bringing potential targets to the user (drag- and-pop). In this paper, we introduce a new technique called push-and-pop that combines the strengths of push-and-throw and drag-and-pop. We present two user studies comparing six different techniques designed for extending drag-and-drop to wall-size displays. In both studies, participants were able to file icons on a wallsize display fastest when using the push-and-pop interface.

This paper details the design and evaluation of the Delphian Desktop, a mechanism for online spatial prediction of cursor movements in a Windows-Icons-Menus-Pointers (WIMP) environment. Interaction with WIMP-based interfaces often becomes a spatially challenging task when the physical interaction mediators are the common mouse and a high resolution, physically large display screen. These spatial challenges are especially evident in overly crowded Windows desktops. The Delphian Desktop integrates simple yet effective predictive spatial tracking and selection paradigms into ordinary WIMP environments in order to simplify and ease pointing tasks. Predictions are calculated by tracking cursor movements and estimating spatial intentions using a computationally inexpensive online algorithm based on estimating the movement direction and peak velocity. In testing the Delphian Desktop effectively shortened pointing time to faraway icons, and reduced the overall physical distance the mouse (and user hand) had to mechanically traverse. ACM Classification: H.5.2 [User Interfaces]: Graphical

Using a new taxonomy of pointing tasks which includes view pointing beside traditional cursor pointing, we introduce the concept of multi-scale pointing. Analyzing the impact of view size, we demonstrate theoretically and experimentally that (1) the time needed to reach a remotely located target in a multi-scale interface still obeys Fitts ’ law and (2) the bandwidth of the interaction (i.e., the inverse of Fitts ’ law slope) is proportional to view size, a relationship bounded by an early ceiling effect. We discuss these results with special reference to navigation in miniaturized and enlarged interfaces. Categories and Subject Descriptors ACM Classification Keywords: