Interface design guidelines encourage designers to provide high-performance mechanisms for expert users. However, research shows that many expert interface components are seldom used and that there is a tendency for users to persistently fail to adopt faster methods for completing their work. This article summarizes and organizes research relevant to supporting users in making successful transitions to expert levels of performance. First, we provide a brief introduction to the underlying human factors of skill acquisition relevant to interaction with computer systems. We then present our focus, which is a review of the state of the art in user interfaces that promote expertise development. The review of interface research is based around four domains of performance improvement: intramodal improvement that occurs as a factor of repetition and practice with a single method of interaction; intermodal improvement that occurs when users switch from one method to another that has a higher performance ceiling; vocabulary extension, in which the user broadens his or her knowledge of the range of functions available; and task mapping, which examines the ways in which users perform their tasks. The review emphasizes the relationship between interface techniques and the human factors that explain their relative success.

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.

Figure 1. FastTap interface. Left: default state of the interface (gridlines enhanced). Center: FastTap grid overlay after touching the activation button. Right: FastTap selection by chording with the thumb and forefinger, without waiting for the overlay. ABSTRACTTouch-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.

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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.