The effect of navigational aids on users' navigation strategies in hypertext systems

Hypertext systems have evolved rapidly in the past few years. This evolution had implications not only on the representation of information but also on navigation tools, with current hypertext systems providing their users with different navigation facilities that enable them to choose the ones that best fit the goal and specificity of their tasks. However, users still have difficulties and feel disoriented while searching or retrieving information within hypertext systems.

One of the first solutions proposed to overcome navigation problems was to control and constrain the degree of freedom offered by hypertext systems. Since this solution would withdraw most of the advantages brought by hypertext systems, more recent alternative solutions recommend the implementation of supplementary navigation tools to provide guidance and facilitate the access to the information contained in the hypertext nodes. These supplementary navigation tools are usually referred to as navigational aids.

This research is concerned with the psychological principles underlying the utilisation of navigational aids. It aims to investigate the added value of different navigational aids in terms of how they improve navigation performance (in searching and retrieval tasks), support users’ memory strategies and enhance their understanding of the hypertext structure. These issues were investigated through a set of sixteen experimental conditions manipulating four variables: the hypertext metaphor (spatial or non-spatial); the navigational aid available (none, global site map, bookmark tool or both); time constraint (time pressure or no time limit); and the type of task to be performed (search or retrieval of specific information nodes).

Overall, the experimental results have shown that the effectiveness of navigational aids varies according to the task being performed; navigational aids involving a deeper level of processing in their utilisation are more vulnerable to time pressure; and a navigational aid providing an overview of the hypertext structure fosters the learning of the hypertext structure only when it is not used in conjunction with a navigational aid that removes the requirement for memorising screens and paths.

From a theoretical point of view, this research demonstrated that navigation should be regarded as a multilevel task involving the development of navigation and memory strategies, planning, maintaining orientation, and acquiring knowledge about the hypertext structure. From a practical point of view, this research has reinforced the importance of task analysis when designing navigational aids.