How the interface design influences users' spontaneous trustworthiness evaluations of web search results

This study examined to what extent users spontaneously evaluate the trustworthiness of Web search results presented by a search engine. For this purpose, a methodological paradigm was used in which the trustworthiness order of search results was experimentally manipulated by presenting search results on a search engine results page (SERP) either in a descending or ascending trustworthiness order. Moreover, a standard list format was compared to a grid format in order to examine the impact of the search results interface on Web users' evaluation processes. In an experiment addressing a controversial medical topic, 80 participants were assigned to one of four conditions with trustworthiness order (descending vs. ascending) and search results interface (list vs. grid) varied as between-subjects factors. In order to investigate participants' evaluation processes their eye movements and mouse clicks were captured during Web search. Results revealed that a list interface caused more homogenous and more linear viewing sequences on SERPs than a grid interface. Furthermore, when using a list interface most attention was given to the search results on top of the list. In contrast, with a grid interface nearly all search results on a SERP were attended to equivalently long. Consequently, in the ascending trustworthiness order participants using a list interface attended significantly longer to the least trustworthy search results and selected the most trustworthy search results significantly less often than participants using a grid interface. Thus, the presentation of Web search results by means of a grid interface seems to support users in their selection of trustworthy information sources.