results are to be retrieved for the search purpose at hand. Users perform-ing most lookup tasks are satisfied if the results are presented as a ranked list of documents in descending order of apparent relevance with regard to the search query entered. A common approach used by IR systems is to optimize the precision and recall of the search results [26]. However, in exploratory search activities, retrieving the results most closely matching the given search query might leave users trapped in their initial query con-text [42]. This behavior contributes to users’ perceptions of exploratory search as challenging. Through a theoretically oriented analysis, I suggest that user performance of exploratory searches can be improved by adapting information retrieval algorithms to retrieve broader result sets for search queries of a certain nature. I have validated this hypothesis with a con-trolled study. Considering the models developed in the earlier stages of the research enabled me to propose a suitable approach for designing an adaptive IR system. The proposed approach involves a system that adapts the diversity level of the retrieved results to the predicted task category. If the search task is predicted to be an exploration, the IR system retrieves a broad set of results, covering a wider spectrum of topics. If, on the other hand, the task is a lookup, the system retrieves the documents that best match the search query. In the thesis, I will provide details of the prototype system implemented in line with the approach described above and present results from user studies confirming that the approach indeed helps users to perform both exploratory and lookup search tasks well.
In summary, the thesis builds a conceptualization of information search that allows development of predictive models of search strategies. The models I propose lead naturally towards development of an IR system that provides adaptive support for both exploratory and lookup search tasks.
1.2 Author’s Contribution
The main claims made in this thesis are based on seven publications, which are referred to in the text by the Roman numerals used below. The partic-ulars of the publications and my contributions to them are detailed below.
Publication I: Kumaripaba Athukorala, Eve Hoggan, Anu Lehti¨o, Tuukka Ruotsalo, and Giulio Jacucci (2013). Information-Seeking Behaviors of Computer Scientists: Challenges for Electronic Litera-ture Search Tools. In: Proceedings of the Association for Information Science and Technology (ASIS&T)(pp. 1–11). Wiley. [7]
Contribution: In collaboration with Giulio Jacucci, I identified the need to investigate information search behaviors in the aim of under-standing the common practices and open challenges. I designed the study, receiving feedback from Giulio Jacucci and Eve Hoggan. Anu Lehti¨o and I conducted the interviews and user observations, and she transcribed the interviews for analysis. I prepared the survey ques-tionnaire and performed both quantitative and qualitative analyses of all data collected, receiving feedback from Eve Hoggan and Tuukka Ruotsalo. I wrote the first version of the manuscript, and all the authors participated in revisions.
Publication II: Kumaripaba Athukorala, Antti Oulasvirta, Dorota Glowacka, Jilles Vreeken, and Giulio Jacucci (2014). Narrow or Broad?:
Estimating Subjective Specificity in Exploratory Search. In: Proceed-ings of the International Conference on Information and Knowledge Management (CIKM) (pp. 819–828). ACM. [11]
Contribution: Building a predictive model addressing searches’ sub-jective specificity from observable exploratory search behaviors was my proposal. Receiving feedback from Antti Oulasvirta, Jilles Vreeken, Dorota Glowacka, and Giulio Jacucci, I developed the formal model and designed and conducted the user study. I performed the initial data analysis and validation of the model, while Jilles Vreeken as-sisted in performing the classification tests. I prepared the first draft of the paper, and all of the authors were involved in the revisions.
Publication III: Kumaripaba Athukorala, Dorota Glowacka, Antti Oulasvirta, Jilles Vreeken, and Giulio Jacucci (2015). Is Exploratory Search Different? A Comparison of Information Search Behavior for Exploratory and Lookup Tasks. Journal of the Association for Infor-mation Science and Technology (JASIST), 1–17. Wiley. [10]
Contribution: I formulated the idea of identifying information search behaviors for purposes of distinguishing between exploratory and lookup tasks. I designed and carried out the data collection, receiving feedback from Dorota Glowacka, Antti Oulasvirta, Jilles Vreeken, and Giulio Jacucci. Then, I analyzed the data, while Jilles Vreeken aided in carrying out the classification tests. I wrote the first version of the manuscript, and all the authors participated in the revision stage.
Publication IV: Kumaripaba Athukorala, Alan Medlar, Kalle Ilves, and Dorota Glowacka (2015). Balancing Exploration and Exploita-tion: Empirical Parameterization of Exploratory Search Systems.
1.2 Author’s Contribution 9 In: Proceedings of the International Conference on Information and Knowledge Management (CIKM) (pp. 1703–1706). ACM. [8]
Contribution: Together with Alan Medlar and Dorota Glowacka, I identified the need to calibrate the exploration rate in an exploratory search system, to enable a suitable balance between exploration and moving toward greater specificity (or exploitation). I designed and conducted the data collection, while Alan Medlar ran simulations to identify exploration rates for analysis in the study. Kalle Ilves supported the implementation of the interface, and Alan Medlar de-signed and developed the back end of the system described in the paper. I analyzed the user satisfaction and performance data, and Alan Medlar analyzed the effect of exploration rate on the number of relevant documents selected. Dorota Glowacka rated the relevance of the user-selected documents. In preparation of the first version of the manuscript, I wrote the “Introduction,” “User Study,” “User Satisfaction and Performance,” and “Discussion and Conclusion” sec-tions, while Alan Medlar and Dorota Glowacka drafted the “System Overview” and “Modelling Document Selection” sections. All authors participated in revisions.
Publication V: Kumaripaba Athukorala, Alan Medlar, Antti
Oulasvirta, Giulio Jacucci, and Dorota Glowacka (2016). Beyond Relevance: Adapting Exploration / Exploitation in Information Re-trieval. In: Proceedings of the International Conference on Intelligent User Interfaces (IUI) (pp. 359–369). ACM. [9]
Contribution: I proposed an approach to adapting exploration ver-sus exploitation in IR systems on the basis of the search task type.
I trained a classifier to predict the search goal and integrated this into a search engine that was developed by Alan Medlar and Dorota Glowacka. Then, I designed and conducted the user study, receiving feedback from Alan Medlar, Antti Oulasvirta, Giulio Jacucci, and Dorota Glowacka. Alan Medlar and I together analyzed the data and wrote the “Results” section of the manuscript, and I drafted the first version of the other parts of the manuscript. All of the authors contributed to the revisions.
Publication VI: Tuukka Ruotsalo, Kumaripaba Athukorala, Dorota Glowacka, Ksenia Konyushkova, Antti Oulasvirta, Samuli Kaipiainen, Samuel Kaski, and Giulio Jacucci (2013). Supporting Exploratory Search Tasks with Interactive User Modeling. In: Proceedings of the
Association for Information Science and Technology (ASIS&T)50(1), 1–10. Wiley. [133]
Contribution: I, in cooperation with Tuukka Ruotsalo, proposed an interface for interactive intent modeling and an approach to its inte-gration into search systems. I implemented system logging to collect user interaction data, while Tuukka Ruotsalo, Ksenia Konyushkova, and Samuli Kaipiainen implemented the retrieval algorithm, intent model, and interactive visualization, respectively. I designed and conducted the user study, receiving feedback from Tuukka Ruot-salo, Dorota Glowacka, Antti Oulasvirta, Samuel Kaski, and Giulio Jacucci. Finally, Tuukka Ruotsalo and I analyzed the data and pre-pared the first version of the manuscript, with all authors participat-ing in revisions.
Publication VII: Dorota Glowacka, Tuukka Ruotsalo, Ksenia
Konyushkova, Kumaripaba Athukorala, Samuel Kaski, and Giulio Jacucci (2013). Directing Exploratory Search: Reinforcement Learn-ing from User Interactions with Keywords. In: Proceedings of the International Conference on Intelligent User Interfaces (IUI) (pp.
117–128). ACM. [64]
Contribution: I was involved in the design of the interactive visual-ization and the system features described in the paper. I designed the user study, receiving feedback on this from Dorota Glowacka, Tuukka Ruotsalo, Samuel Kaski, and Giulio Jacucci. Ksenia Konyushkova, Dorota Glowacka, Tuukka Ruotsalo, and I conducted the user studies.
I analyzed the user responses from the questionnaire and wrote the first version of the “User Experiment” section. All authors took part in revisions to the rest of the paper, which Dorota Glowacka had the primary role in the writing.