Workshop at HCI 2004
The 18th British HCI Group Annual Conference
Leeds Metropolitan University, UK 6-10 September 2004

The fast shift of attention from one subject to another or one activity to another is one of the consequences of information overload. In certain situations the ability to quickly access several information sources, to switch activities, or to change context is advantageous. In other situations it would be more fruitful to create and maintain a focus whilst offering the possibility to switch attention to other contents or activities. This is especially the case in domains where the lack of knowledge and experience of users with the subject at hand may cause a loss of focus, but it also applies to other situations. A large portion of research on human attention in digital environments is based on the findings of cognitive psychology (e.g. Raskin [9]), or experimental psychology (e.g. Bearne [1]). Such studies are characterised by the aim of supporting the attentional choices of the user making the device transparent.
Another area of research focuses instead on designing interfaces and systems capable of guiding the user in the choice of attentional focus. Some of these act as proactive helpers for the user [6-8]. The two approaches are very often regarded as divergent, responding to different needs and requiring different design choices. We believe that this is not necessarily the case. We should not aim at designing transparent or proactive systems. Rather we should aim at designing systems capable of reasoning about users' attention, and consequently decide how best to disappear or to gain and guide user's attention. Focusing on attentional mechanisms also provides a framework that reconciles the direct manipulation user interfaces approach and the interface agents approach as clearly presented and exemplified by Horviz [3].
Reasoning about user's attention must encompass reasoning about reactive processes controlling attention and deliberative processes controlling attention. Further more these processes must be co-ordinated to explain situations in which deliberative process are initiated by reactive processes (e.g. attention shift caused by a visual stimulus), or reactive processes are pruned by deliberative process (e.g. certain external stimuli are not noticed because one's attention is focused elsewhere). Some interesting results in modelling attention as the necessary link between cognition and perception are reported by Hill [2] in his system simulating a virtual human pilot.
A complete account of attentional mechanisms however must take into consideration two more processes that interplay with the reactive and deliberative ones. These are social processes and aesthetic processes controlling attention.