This thesis reports results of a research study into the usefulness of a user-centred approach for designing information retrieval interfaces. The main objective of the research was to examine the usability of an existing Web-based IR system in order to design a user-centred prototype Web interface. A series of usability experiments was carried out with the Web of Science. The first experiment was carried out using both novice and experienced users to see their performance and satisfaction with the interface. A set of search tasks was obtained from a user survey and was used in the study. The results showed that there were no significant differences in the time taken to complete the tasks, and the number of different search terms used between the two search groups. Novice users were significantly more satisfied with the interface than the experienced group. However, the experienced group was significantly more successful, and made fewer errors than the novice users. The second experiment was conducted on novices' learning and retention with the Web of Science using the same equipment, tasks and environment. The results of the original learning phase of the experiment showed that novices could readily pick up interface functionality when a brief training was provided. However, their retention of search skills weakened over time. Their subjective satisfaction with the interface also diminished from learning to retention. These findings suggested that the fundamental difficulties of searching IR systems still remain with the Web-based version. A heuristic evaluation was carried out to find out the usability problems in the Web of Science interface. Three human factors experts evaluate the interface. The heuristic evaluation was very helpful in identifying some interface design issues for Web IR systems. The most fundamental of these was increasing the match between system and the real world. The results of both the usability testing and the heuristic evaluations served as a baseline for designing a prototype Web interface. The prototype was designed based on a conceptual model of users' information seeking. Various usability evaluation methods were used to test the usability of the prototype system. After each round of testing, the interface was modified in accordance with the test findings. A summative evaluation of the prototype interface showed that both novice and experienced users improved their search performance. Comparative analysis with the earlier usability studies also showed significant improvements in performance and satisfaction with the prototype. These results show that user-centred methods can yield better interface design for IR systems.

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