Comprehension effects of signalling relationships between documents in search engines

A key task for students learning about a complex topic from multiple documents on the web is to establish the existing rhetorical relations between the documents. Traditional search engines such as Google® display the search results in a listed format, without signalling any relationship between the documents retrieved. New search engines such as Kartoo® go a step further, displaying the results as a constellation of documents, in which the existing relations between pages are made explicit. This presentation format is based on previous studies of single-text comprehension, which demonstrate that providing a graphical overview of the text contents and their relation boosts readers’ comprehension of the topic. We investigated the assumption that graphical overviews can also facilitate multiple-documents comprehension. The present study revealed that undergraduate students reading a set of web pages on climate change comprehended them better when using a search engine that makes explicit the relationships between documents (i.e. Kartoo-like) than when working with a list-like presentation of the same documents (i.e. Google-like). The facilitative effect of a graphical-overview interface was reflected in inter-textual inferential tasks, which required students to integrate key information between documents, even after controlling for readers’ topic interest and background knowledge.