Identifying a target command can be difficult and time-consuming when the user is unfamiliar with a software system. One technique for assisting command identification is to provide a subset interface that contains only a limited set of the system's capabilities. We examine the design of subset interfaces, showing that subsets can be presented separately to the full user interface (UI) (e.g. in a palette) or in place, with in-place methods using either static or dynamic methods to identify the subset. We introduce the StencilMap and EphemeralMap as in-place subset UIs that, respectively, use static and dynamic highlighting. Both StencilMaps and EphemeralMaps make all of an application's commands concurrently available for selection within a grid. To highlight subset items StencilMaps use a static dark semi-transparent ‘stencil’ overlay to de-emphasise all but the subset items; EphemeralMaps, in contrast, use a short delay, with subset items shown immediately, and other items gradually faded in. A first experiment compares user performance with the in-place presentation of StencilMaps against that of the separate presentation of a subset palette. Results confirm the predicted spatial memory benefits for StencilMaps. A second experiment analyses the performance impact of three approaches to highlighting: none, static highlighting in StencilMaps, and dynamic highlighting in EphemeralMaps. Results show an interesting trade-off – while highlighting can offer benefits in assisting rapid target identification (particularly when the user is unfamiliar with the interface layout), there can also be longer-term performance benefits when highlighting is absent because the increased difficulty of visual search promotes the use and formation of spatial memory.

Touch-based tablet UIs provide few shortcut mechanisms for rapid command selection; as a result, command selection on tablets often requires slow traversal of menus. We developed a new selection technique for multi-touch tablets, called FastTap, that uses thumb-and-finger touches to show and choose from a spatially-stable grid-based overlay interface. FastTap allows novices to view and inspect the full interface, but once item locations are known, FastTap allows people to select commands with a single quick thumb-and-finger tap. The interface helps users develop expertise, since the motor actions carried out as a novice rehearse the expert behavior. A controlled study showed that FastTap was significantly faster (by 33% per selection overall) than marking menus, both for novices and experts, and without reduction in accuracy or subjective preference. Our work introduces a new and efficient selection mechanism that supports rapid command execution on touch tablets, for both novices and experts.

CommandMaps are a promising interface technique that flattens command hierarchies and exploits human spatial memory to provide rapid access to commands. CommandMaps have performed favorably in constrained cued-selection studies, but have not yet been tested in the context of real tasks. In this paper we present two real-world implementations of CommandMaps: one for Microsoft Word and one for an image editing program called Pinta. We use these as our experimental platforms in two experiments. In the first, we show that CommandMaps demonstrate performance and subjective advantages in a realistic task. In the second, we observe naturalistic use of CommandMaps over the course of a week, and gather qualitative data from interviews, questionnaires, and conversations. Our results provide substantial insight into users' reactions to CommandMaps, showing that they are positively received by users and allowing us to provide concrete recommendations to designers regarding when and how they should be implemented in real applications.

Relative spatial consistency - that is, the stable arrangement of objects in a 2D presentation - provides several benefits for interactive interfaces. Spatial consistency allows users to develop memory of object locations, reducing the time needed for visual search, and because spatial memory is long lasting and has a large capacity these performance benefits are enduring and scalable. This suggests that spatial consistency could be used as a fundamental principle for the design of interfaces. However, there are many display situations where the standard presentation is altered in some way: e.g., a window is moved to a new location, scaled, or rotated on a mobile or tabletop display. It is not known whether the benefits of spatial organization are robust to these common kinds of view transformation. To assess these effects, we tested user performance with a spatial interface that had been transformed in several ways, including different degrees of translation, rotation, scaling, and perspective change. We found that performance was not strongly affected by the changes, except in the case of large rotations. To demonstrate the value of spatial consistency over existing mechanisms for dealing with view changes, we compared user performance with a spatially-stable presentation (using scaling) with that of a 'reflowing' presentation (widely used in current interfaces). This study showed that spatial stability with scaling dramatically outperforms reflowing. This research provides new evidence of spatial consistency's value in interface design: it is robust to the view transformations that occur in typical environments, and it provides substantial performance advantages over traditional methods.

Applications typically provide ways for expert users to increase their performance, such as keyboard shortcuts or customization, but these facilities are frequently ignored. To help address this problem, we introduce skillometers -- lightweight displays that visualize the benefits available through practicing, adopting a better technique, or switching to a faster mode of interaction. We present a general framework for skillometer design, then discuss the design and implementation of a real-world skillometer intended to increase hotkey use. A controlled experiment shows that our skillometer successfully encourages earlier and faster learning of hotkeys. Finally, we discuss general lessons for future development and deployment of skillometers.

Designers of GUI applications typically arrange commands in hierarchical structures, such as menus, due to screen space limitations. However, hierarchical organisations are known to slow down expert users. This paper proposes the use of spatial memory in combination with hierarchy flattening as a means of improving GUI performance. We demonstrate these concepts through the design of a command selection interface, called CommandMaps, and analyse its theoretical performance characteristics. We then describe two studies evaluating CommandMaps against menus and Microsoft's Ribbon interface for both novice and experienced users. Results show that for novice users, there is no significant performance difference between CommandMaps and traditional interfaces -- but for experienced users, CommandMaps are significantly faster than both menus and the Ribbon.

Interface guidelines encourage designers to include shortcut mechanisms that enable high levels of expert performance, but prior research has demonstrated that few users switch to using them. To help understand how interfaces can better support a transition to expert performance we develop a framework of the interface and human factors influencing expertise development. We then present a system called Blur that addresses three main problems in promoting the transition: prompting an initial switch to expert techniques, minimising the performance dip arising from the switch, and enabling a high performance ceiling. Blur observes the user's interaction with unaltered desktop applications and uses calm notification to support learning and promote awareness of an alternative hot command interface. An empirical study validates Blur's design, showing that users make an early and sustained switch to hot commands, and that doing so improves their performance and satisfaction.