Re-finding behaviour in vertical domains

Re-finding is the process of searching for information that a user has previously encountered and is a common activity carried out with information retrieval systems. In this work, we investigate re-finding in the context of vertical search, differentiating and modeling user re-finding behavior within different media and topic domains, including images, news, reference material, and movies. We distinguish the re-finding behavior in vertical domains from re-finding in a general search context and engineer features that are effective in differentiating re-finding across the domains. The features are then used to build machine-learned models, achieving an accuracy of re-finding detection in verticals of 85.7% on average. Our results demonstrate that detecting re-finding in specific verticals is more difficult than examining re-finding for general search tasks. We then investigate the effectiveness of differentiating re-finding behavior in two restricted contexts: We consider the case where the history of a searcher's interactions with the search system is not available. In this scenario, our features and models achieve an average accuracy of 77.5% across the domains. We then examine the detection of re-finding during the early part of a search session. Both of these restrictions represent potential real-world search scenarios, where a system is attempting to learn about a user but may have limited information available. Finally, we investigate in which types of domains re-finding is most difficult. Here, it would appear that re-finding images is particularly challenging for users. This research has implications for search engine design, in terms of adapting search results by predicting the type of user tasks and potentially enabling the presentation of vertical-specific results when re-finding is identified. To the best of our knowledge, this is the first work to investigate the issue of vertical re-finding.