Playing Your Cards Right: The Effect of Entity Cards on Search Behaviour and Workload.

In addition to merging results of different types (e.g.~images, videos, news items) into a ranked list of Web documents, modern search engines have also started displaying entity cards (ECs) on the results page. Entity cards are intended to enhance search experience in several ways: (i) they help searchers navigate diversified results, (ii) provide a summary of relevant content directly on the results page and (iii) support exploratory search by highlighting relevant entities associated with a given user query. We conducted a large-scale crowd-sourced user study, with more than $700$ unique searchers, to investigate the effects of entity cards on search behaviour and perceived workload. We find that the presence of ECs has a strong effect on both the way users interact with search results and their perceived task workload. Furthermore, by manipulating EC properties content, coherence and vertical diversity), we uncover different effects and interactions between card properties on measures of search behaviour and workload. Our study contributes an in-depth analysis of the effects of entity cards on user interaction with modern Web search interfaces.