| The role of top-down and bottom-up processes in visual search is a crucial topic that has received considerable attention. This dissertation first reviews the literature on the visual attributes that guide attention in visual search. It is argued that studies of attentional capture should play an important role in determining these guiding attributes. Attentional capture paradigms are well-suited for unveiling the search strategies that subjects use in visual search and for understanding the relative roles of bottom-up and top-down guidance. Several studies have addressed the issue of search strategy in visual search for a single feature (e.g., Bacon & Egeth, 1994; Theeuwes, 1991). Although additional studies have addressed the role of top-down and bottom-up processes in conjunction search with unequal distractor ratios (e.g., Bacon & Egeth, 1997; Sobel & Cave, 2002), only two experiments have attempted to examine this issue by modifying a standard conjunction search task with equal distractor ratios (Lamy & Tsal, 1999; Friedman-Hill & Wolfe, 1995). A novel visual search procedure was designed for this dissertation to address the role of top-down and bottom-up processes in visual search for conjunctions. The main result is that, surprisingly, bottom-up processes guide attention in a conjunction search task. |
