StencilMaps and EphemeralMaps: spatially stable interfaces that highlight command subsets

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.