Task and activity models in hypertext usage

In this chapter we examine hypertext usage from the point of view of the information processing tasks performed by hypertext users. Our main purpose is to provide a general framework to identify the tasks which may be effectively supported by hypertext environments. First we present different approaches to the analysis of information processing tasks, as they appear in hypertext and information retrieval literature: Formal, user-centered and integrated. Then we review empirical studies focusing on the cognitive processes involved in hypertext usage. We examine two general types of tasks: Information search tasks and learning/exploration tasks. Based on these studies we suggest that hypertext usage requires the user to build up a task representation and a task management strategy. These two processes are influenced by individual as well as situational factors. Finally we propose a general framework to represent the task and activity levels involved in using hypertext. The framework includes three levels of analysis: The rational or formal level, the cognitive task representation level and cognitive task management level. The latter is further analyzed as a cycle that includes goal evaluation, selection and processing of goal-relevant information. We briefly discuss the implications of this framework for hypertext design and assessment. 1