Result diversification aims to provide searchers with a broader view of a given topic while attempting to maximise the chances of retrieving relevant material. Diversifying results also aims to reduce search bias by increasing the coverage over different aspects of the topic. As such, searchers should learn more about the given topic in general. Despite diversification algorithms being introduced over two decades ago, little research has explicitly examined their impact on search behaviour and performance in the context of Interactive Information Retrieval (IIR). In this paper, we explore the impact of diversification when searchers undertake complex search tasks that require learning about different aspects of a topic (aspectual retrieval). We hypothesise that by diversifying search results, searchers will be exposed to a greater number of aspects. In turn, this will maximise their coverage of the topic (and thus reduce possible search bias). As a consequence, diversification should lead to performance benefits, regardless of the task, but how does diversification affect search behaviours and search satisfaction? Based on Information Foraging Theory (IFT), we infer two hypotheses regarding search behaviours due to diversification, namely that (i) it will lead to searchers examining fewer documents per query, and (ii) it will also mean searchers will issue more queries overall. To this end, we performed a within-subjects user study using the TREC AQUAINT collection with 51 participants, examining the differences in search performance and behaviour when using (i) a non-diversified system (BM25) versus (ii) a diversified system (BM25 + xQuAD) when the search task is either (a) ad-hoc or (b) aspectual. Our results show a number of notable findings in terms of search behaviour: participants on the diversified system issued more queries and examined fewer documents per query when performing the aspectual search task. Furthermore, we showed that when using the diversified system, participants were: more successful in marking relevant documents, and obtained a greater awareness of the topics (i.e. identified relevant documents containing more novel aspects). These findings show that search behaviour is influenced by diversification and task complexity. They also motivate further research into complex search tasks such as aspectual retrieval—and how diversity can play an important role in improving the search experience, by providing greater coverage of a topic and mitigating potential bias in search results.

中文翻译：

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结果多样化对搜索行为和性能的影响

结果多样化旨在向搜索者提供给定主题的更广泛视野，同时尝试最大程度地检索相关材料的机会。多样化的结果还旨在通过增加主题不同方面的覆盖范围来减少搜索偏见。因此，搜索者应该大致了解有关给定主题的更多信息。尽管在二十多年前引入了多样化算法，但是很少有研究明确地研究了它们在交互式信息检索（IIR）的背景下对搜索行为和性能的影响。在本文中，我们探讨了当搜索者执行复杂的搜索任务（需要了解某个主题的不同方面（纵横检索））时，多元化的影响。。我们假设通过使搜索结果多样化，搜索者将面临更多的方面。反过来，这将最大程度地扩大他们对该主题的报道范围（从而减少可能的搜索偏见）。结果，无论任务如何，多样化都应该带来性能收益，但是多样化如何影响搜索行为和搜索满意度？基于信息搜寻理论（IFT），我们推断出关于多样化导致的搜索行为的两个假设，即（i）这将导致搜索者检查每个查询的文档更少；（ii）这也将意味着搜索者将总体上发出更多的查询。为此，我们使用TREC AQUAINT对受试者进行了用户研究收集了51位参与者的信息，检查了在使用（i）非多元化系统（BM25）与（ii）多元化系统（BM25 +  xQuAD）时搜索性能和行为的差异）（当搜索任务是（a）即席或（b）方面的）时。我们的结果显示出在搜索行为方面的许多显着发现：在执行方面搜索任务时，多元化系统的参与者发出了更多的查询，并且每个查询检查的文档更少。此外，我们表明，使用多元化的系统时，参与者可以：在标记相关文件时更加成功，并且对主题有更高的意识（即，确定的包含更多新颖方面的相关文件）。这些发现表明，搜索行为受多元化和任务复杂性的影响。他们还激发了对复杂搜索任务（例如方面检索）的进一步研究的动机，以及多样性如何在改善搜索体验中发挥重要作用，