  While current information retrieval systems are effective for known-item
retrieval where the searcher provides a precise name or identifier for the item
being sought, systems tend to be much less effective for cases where the
searcher is unable to express a precise name or identifier. We refer to this as
tip of the tongue (TOT) known-item retrieval, named after the cognitive state
of not being able to retrieve an item from memory. Using movie search as a case
study, we explore the characteristics of questions posed by searchers in TOT
states in a community question answering website. We analyze how searchers
express their information needs during TOT states in the movie domain.
Specifically, what information do searchers remember about the item being
sought and how do they convey this information? Our results suggest that
searchers use a combination of information about: (1) the content of the item
sought, (2) the context in which they previously engaged with the item, and (3)
previous attempts to find the item using other resources (e.g., search
engines). Additionally, searchers convey information by sometimes expressing
uncertainty (i.e., hedging), opinions, emotions, and by performing relative
(vs. absolute) comparisons with attributes of the item. As a result of our
analysis, we believe that searchers in TOT states may require specialized query
understanding methods or document representations. Finally, our preliminary
retrieval experiments show the impact of each information type presented in
information requests on retrieval performance.
