bers of Objects
Integrated Publication and Information Systems Institute ( IPSI)
German National Research Center for Information Technology ( GMD)
64293 Darmstadt, Germany
When retrieving information from databases or search engines, or when configuring user profiles of information filtering systems, users have to describe what objects to retrieve. While some systems require users to describe their needs using textual input, other systems simplify the users' task by proposing a set of items, so that the user's task is reduced to picking or rating these items (e.g. relevance feedback (Haines 93). This task is generally much simpler than writing queries from scratch. In interfaces of this type, users have to provide information of the type "does this item represent my information interest", "do I like this item" or "how much do I like this item". Similar problems are encountered in utility theory, when assessing the user's value functions ( Keeney and Raiffa 76). As an example, Figure 1 shows such a selection user interface. It allows users the selection of TV channels, e.g. to configure their user profile for a TV recommender system. The interface contains about sixty toggle switches.
Assessing a large number of items can be time consuming. How can interfaces handle hundreds of such selection or assessment tasks in an efficient way? Sometimes it is possible to aggregate objects or to provide good defaults, so that only a few objects have to be manipulated in the first place. But what to do if there are no good defaults or too many of them? The set of TV channels that users can receive depends not only on the carrier, such as cable or satellite, but also varies widely depending on the local provider and subscriptions to pay-TV. If the interface provided extra buttons for every useful default configuration, the number of these buttons could easily exceed the number of actual toggles in the interface.