Actively engaging learners with learning materials has been shown to be very important in the Search as Learning (SAL) setting. One active reading strategy relies on asking so-called adjunct questions, i.e., manually curated questions geared towards essential concepts of the target material. However, manual question creation is impractical given the vast online content. Recent research has explored the effects of Automatic Question Generation (AQG) on aiding human learning. These studies have primarily focused on user studies in controlled online reading scenarios with limited documents. However, the impacts of adjunct questions on learning in the SAL setting, which involves learning through web searching, are not yet well understood. This paper addresses this gap by conducting a user study with automatically generated adjunct questions integrated into the reading interface built on top of a search system. We conducted a between-subjects user study (N = 144) to investigate the incorporation of automatically generated adjunct questions on participants' learning. We employed three different question generation strategies as well as a control condition: (i) synthesis questions; (ii) factoid questions targeting random text spans; and (iii) factoid questions targeting terms and phrases relevant to the information need at hand. We present four major findings: (i) participants who received adjunct questions exhibited significantly more fine-grained reading behaviour, such as longer document dwell time and more scrolls, than those without adjunct questions. However, adjunct questions' influence on learning outcomes depends on the AQG strategy. (ii) Question types significantly influence participants' reading behaviour. (iii) The adjunct questions' target spans significantly influence learning outcomes. Lastly, (iv) participants' prior knowledge levels affect adjunct questions' effects on their learning outcomes and their reaction to different AQG strategies. Our findings have significant design implications for learning-oriented search systems. The data and code is available at https://github.com/zpeide/AQG-AdjunctQuestions.

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At the core of Search-as-Learning (SAL), as a sub-field of Interactive Information Retrieval (IIR), is exploring how people use search engines to acquire knowledge. Inherently interactive, the knowledge acquisition process via a search system involves learners posing queries, analyzing content, and incorporating novel knowledge. Being this iterative process, learning-oriented systems should be designed to support learners in their search process. In this thesis, we study how to design such systems by leveraging concepts from Natural Language Processing (NLP), Information Retrieval (IR), and the learning sciences. We begin this thesis by proposing interventions in a search system to better support learners in their journey with ideas based on instructional scaffolding from the learning sciences. The data collected from this user study gives us insights into how learners interact with search systems and provides us with a rich dataset for the rest of the thesis. With that data available, the rest of this thesis focuses on modeling learner behavior using different paradigms and frameworks. We begin by simulating learners’ behavior, proposing a novel searcher model based on the idea that learning topics are usually subdivided into subtopics. Then, we propose a framework for tracking and predicting a learner’s knowledge state throughout their search session. By using only the information in the documents read by the learner, this framework can accurately predict the learner’s knowledge at the end of their session. Finally, we look into SAL using the underexplored perspective of causality. While most previous works, including our own, mainly look into the correlations between behavior and learning, we take PLS-SEM, a causal modeling technique, to study the causal relationships between the different variables involved in the learning process and how this intricate and complex interactive process unfolds. From this analysis, we not only identify some interesting causal relationships, such as the indirect impact of query quality on learning but also show that the common practice of assessing learning by multiple-choice questions does not fully capture the variability of the learning process. This thesis, therefore, contributes to the field of Search-as-Learning by making all of our datasets and code for simulating and modeling learner behavior available. We also provide several insights into how learners behave while searching and the impact of these behaviors on their learning outcomes. We hope the findings in this thesis can be used as foundations for more principled improvements in learning-oriented search systems.@en

A reliable representation of the user's knowledge state during a learning search session is crucial to understand their real information needs. When a search system is aware of such a state, it can adapt the search results and provide greater support for the user's learning objectives. A common practice to track the user's knowledge state is to consider the content of the documents they read during their search session(s). However, most current work ignores entity mentions in the documents, which, when linked to knowledge graphs, can be a source of valuable information regarding the user's knowledge. To fill this gap, we extend RULK - Representing User Knowledge in Search-as-Learning - with entity linking capabilities. The extended framework RULK represents and tracks user knowledge as a collection of such entities. It eventually estimates the user knowledge gain - learning outcome - by measuring the similarity between the represented knowledge and the learning objective. We show that our methods allow for up to 10% improvements when estimating user knowledge gains.

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Complex search tasks—such as those from the Search as Learning (SAL) domain—often result in users developing an information need composed of several aspects. However, current models of searcher behaviour assume that individuals have an atomic need, regardless of the task. While these models generally work well for simpler informational needs, we argue that searcher models need to be developed further to allow for the decomposition of a complex search task into multiple aspects. As no searcher model yet exists that considers both aspects and the SAL domain, we propose, by augmenting the Complex Searcher Model (CSM), the Subtopic Aware Complex Searcher Model (SACSM)—modelling aspects as subtopics to the user’s need. We then instantiate several agents (i.e., simulated users), with different subtopic selection strategies, which can be considered as different prototypical learning strategies (e.g., should I deeply examine one subtopic at a time, or shallowly cover several subtopics?). Finally, we report on the first large-scale simulated analysis of user behaviours in the SAL domain. Results demonstrate that the SACSM, under certain conditions, simulates user behaviours accurately.

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Heavily pre-trained transformers for language modeling, such as BERT, have shown to be remarkably effective for Information Retrieval (IR) tasks, typically applied to re-rank the results of a first-stage retrieval model. IR benchmarks evaluate the effectiveness of retrieval pipelines based on the premise that a single query is used to instantiate the underlying information need. However, previous research has shown that (I) queries generated by users for a fixed information need are extremely variable and, in particular, (II) neural models are brittle and often make mistakes when tested with modified inputs. Motivated by those observations we aim to answer the following question: how robust are retrieval pipelines with respect to different variations in queries that do not change the queries’ semantics? In order to obtain queries that are representative of users’ querying variability, we first created a taxonomy based on the manual annotation of transformations occurring in a dataset (UQV100) of user-created query variations. For each syntax-changing category of our taxonomy, we employed different automatic methods that when applied to a query generate a query variation. Our experimental results across two datasets for two IR tasks reveal that retrieval pipelines are not robust to these query variations, with effectiveness drops of ≈ 20 % on average. The code and datasets are available at https://github.com/Guzpenha/query_variation_generators.

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Models developed to simulate user interactions with search interfaces typically do not consider the visual layout and presentation of a Search Engine Results Page (SERP). In particular, the position and size of interfacewidgets ---such as entity cards and query suggestions---are usually considered a negligible constant. In contrast, in this work, we investigate the impact of widget positioning on user behaviour. To this end, we focus on one specific widget: the Query History Widget (QHW). It allows users to see (and thus reflect) on their recently issued queries. We build a novel simulation model based on Search Economic Theory (SET) that considers how users behave when faced with such a widget by incorporating its positioning on the SERP. We derive five hypotheses from our model and experimentally validate them based on user interaction data gathered for an ad-hoc search task, run across five different placements of the \qhw on the SERP. We find partial support for three of the five hypotheses, and indeed observe that a widget's location has a significant impact on search behaviour.@en

Web search engines are today considered to be the primary tool to assist and empower learners in finding information relevant to their learning goals- be it learning something new, improving their existing skills, or just fulfilling a curiosity. While several approaches for improving search engines for the learning scenario have been proposed (e.g. a specific ranking function), instructional scaffolding (or simply scaffolding)-a traditional learning support strategy-has not been studied in the context of search as learning, despite being shown to be effective for improving learning in both digital and traditional learning contexts. When scaffolding is employed, instructors provide learners with support throughout their autonomous learning process. We hypothesize that the usageof scaffolding techniques within a search system can be an effective way to help learners achieve their learning objectives whilst searching. As such, this paper investigates the incorporation of scaffolding into a search system employing three different strategies (as well as a control condition): (i) AQe, the automatic expansion of user queries with relevant subtopics; (ii) CURATEDsc, the presenting of a manually curated static list of relevant subtopics on the search engine result page; and (iii) FEEDBACKsc, which projects real-time feedback about a user's exploration of the topic space on top of the CURATEDsc visualization. To investigate the effectiveness of these approaches withrespect to human learning, we conduct a user study (N=126) where participants were tasked with searching and learning about topics such as genetically modified organisms. We find that (i) the introduction of the proposed scaffolding methods in the proposed topics does not significantly improve learning gains. However, (ii) it does significantly impact search behavior. Furthermore, (iii) immediate feedback of the participants' learning (FEEDBACKsc) leads to undesirable user behavior, with participants seemingly focusing on the feedback gauges instead of learning.

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Word embeddings, made widely popular in 2013 with the release of word2vec, have become a mainstay of NLP engineering pipelines. Recently, with the release of BERT, word embeddings have moved from the term-based embedding space to the contextual embedding space—each term is no longer represented by a single low-dimensional vector but instead each term and its context determine the vector weights. BERT’s setup and architecture have been shown to be general enough to be applicable to many natural language tasks. Importantly for Information Retrieval (IR), in contrast to prior deep learning solutions to IR problems which required significant tuning of neural net architectures and training regimes, “vanilla BERT” has been shown to outperform existing retrieval algorithms by a wide margin, including on tasks and corpora that have long resisted retrieval effectiveness gains over traditional IR baselines (such as Robust04). In this paper, we employ the recently proposed axiomatic dataset analysis technique—that is, we create diagnostic datasets that each fulfil a retrieval heuristic (both term matching and semantic-based)—to explore what BERT is able to learn. In contrast to our expectations, we find BERT, when applied to a recently released large-scale web corpus with ad-hoc topics, to not adhere to any of the explored axioms. At the same time, BERT outperforms the traditional query likelihood retrieval model by 40%. This means that the axiomatic approach to IR (and its extension of diagnostic datasets created for retrieval heuristics) may in its current form not be applicable to large-scale corpora. Additional—different—axioms are needed.

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Reproducibility and replicability are key concepts in science, and it is therefore important for information retrieval (IR) platforms to aid in reproducing and replicating experiments. In this paper, we describe the creation of a Docker container for Terrier within the framework of the OSIRRC 2019 challenge, which allows typical runs to be reproduced on TREC Test Collections such as Robust04, GOV2, Core2018. In doing so, it is hoped that the produced Docker image can be of aid to other (re)producing baseline experiments on these test collections. Initiatives like OSIRRC are key in advancing these key concepts in the IR area. By making not only the source code available, but also the exact same environment and standardising inputs and outputs, it is possible to easily compare approaches and thereby improve the quality of the research for Information Retrieval.@en

This demo presents a system for journalists to explore video footage for broadcasts. Daily news broadcasts contain multiple news items that consist of many video shots and searching for relevant footage is a labor intensive task. Without the need for annotated video shots, our system extracts semantics from footage and automatically matches these semantics to query terms from the journalist. The journalist can then indicate which aspects of the query term need to be emphasized, e.g. the title or its thematic meaning. The goal of this system is to support the journalists in their search process by encouraging interaction and exploration with the system.@en

As search systems gradually turn into intelligent personal assistants, users increasingly resort to a search engine to accomplish a complex task, such as planning a trip, renting an apartment, or investing in stocks. A key challenge for the search engine is to understand the user's underlying task given a sample query like “tickets to Panama”, “studios in los angeles”, or “spotify stocks”, and to suggest other queries to help the user complete the task. In this paper, we investigate several strategies for query recommendation by traversing a semantically annotated query log using a mixture of explicit and latent representations of entire queries and of query segments. Our results demonstrate the efectiveness of these strategies in terms of utility and diversity, as well as their complementarity, with signifcant improvements compared to state-of-the-art query recommendation baselines adapted for this task.

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