A Study of Snippet Length and Informativeness

Œe design and presentation of a Search Engine Results Page (SERP) has been subject to much research. With many contemporary aspects of the SERP now under scrutiny, work still remains in investigating more traditional SERP components, such as the result summary. Prior studies have examined a variety of di‚erent aspects of result summaries, but in this paper we investigate the inƒuence of result summary length on search behaviour, performance and user experience. To this end, we designed and conducted a withinsubjects experiment using the TREC AQUAINT news collection with 53 participants. Using Kullback-Leibler distance as a measure of information gain, we examined result summaries of di‚erent lengths and selected four conditions where the change in information gain was the greatest: (i) title only; (ii) title plus one snippet; (iii) title plus two snippets; and (iv) title plus four snippets. Findings show that participants broadly preferred longer result summaries, as they were perceived to be more informative. However, their performance in terms of correctly identifying relevant documents was similar across all four conditions. Furthermore, while the participants felt that longer summaries were more informative, empirical observations suggest otherwise; while participants were more likely to click on relevant items given longer summaries, they also were more likely to click on non-relevant items. Œis shows that longer is not necessarily beŠer, though participants perceived that to be the case – and second, they reveal a positive relationship between the length and informativeness of summaries and their aŠractiveness (i.e. clickthrough rates). Œese €ndings show that there are tensions between perception and performance when designing result summaries that need to be taken into account.