The ostensive model of developing information needs

We present a model of the progressive development of information needs. It is a model that recognises the changing uncertainty inherent in a user’s cognition of his information need. The approach centres around the collection and combination of ostensive evidence. We present uncertainty profiles associated with the discounting of ostensive evidence with respect to its age, and relate that to a new notion of relevance Ostensive Relevance. This notion recognises the transient, inaccessible, spatio-temporal nature of relevance. We describe how these components come together to allow the Ostensive Model to be integrated with the traditional Binary Probabilistic Model. We describe the integration and show that it reveals an implicit assumption in the conventional estimation procedure for a particular conditional probability. The temporal aspects of the Ostensive Model allow a weakening of that assumption. The integration allows direct implementation of the Ostensive Model. Finally, we present an example that demonstrates the intuitive appeal of the approach over existing approaches to Relevance Feedback.