Evaluating the utility and usability of an adaptive hypermedia system

We have evaluated an adaptive hypermedia system, PUSH, and compared it to a non-adaptive variant of the same system. Based on an inferred information-seeking task, PUSH chooses what to show and what to hide in a page using a stretchtext technique, thus attempting to avoid information overload. We studied how successful the subjects were in retrieving the most relevant information, and found that the subjects' solutions were influenced by the choice made by the adaptive system. We also studied how much the adaptivity reduced the amount of actions needed, and found that subjects made substantially fewer actions in the adaptive case. A third measurement was the subjects' subjective preferences for the adaptive or the non-adaptive system, where we found that the subjects clearly preferred the adaptive system. It seems as if the adaptive system requires fewer decisions on behalf of the subject, thereby reducing the cognitive load. (C) 1998 Elsevier Science B.V. All rights reserved.