Task difficulty and domain knowledge effects on information search behaviors

This study explores the effect of task difficulty on search behavior changes for users with high and low domain knowledge. A user experiment (n=40) was conducted using 5 search tasks. Participants rated their knowledge of MeSH terms (n=409) and were divided into two domain knowledge levels. Three of the tasks were designed to be difficult tasks with very few relevant documents returned by our search system and two tasks were easy, with many relevant documents returned. Our results showed that in Difficult tasks, users spent significantly longer dwell time on search result pages and visited significantly more content pages than in Easy tasks. In addition, there was an interaction effect of task difficulty and domain knowledge on dwell time of content pages and the percentage of dwell time on content pages to the task completion time. Our results demonstrate that the dwell time on search result pages is a better indicator of task difficulty than the dwell time on content pages if users' domain knowledge level is unknown. Our results have implications for personalization of information retrieval.