Web search engines have become a useful tool helping Web users seek required information. Such Web sites typically present searched results as a textual list that may include thousands of Web pages. Because of the unstructured content and format of information that searchers receive, they often feel the pressure of information overload, which will inevitably compromise the quality of decision-making. Although researchers as well as practitioners have developed various information visualization approaches to enhance information presentation on Web search engines, the benefits of using such technology are unknown. This study will investigate whether and under what circumstances visualization of search results enhances users’ search performance. Cognitive fit theory will be used as the theoretical foundation of this paper. The objectives of the paper are 1) to extent cognitive fit theory in the emergent domain of Web searching, 2) to understand the effects of the user interface on search performance, and 3) to guide search engine designers on how to best present results to support different search tasks.