This study examines consumer information processing heuristics in the context of ambient task complexity. Individual consumers are often called upon to make evaluations of product and advertising stimuli while ambient events not directly related to the purchase at hand may enter the evaluative process and influence the way evaluations are made. Subjects facing a more complex task due to ambient events were found to evaluate the target stimulus in a way that was more consistent with category-based rather than piecemeal processing. Additionally, the findings provide considerable evidence for stereotype-driven evaluations and processing of attribute information. The theoretical and practical implications of this research are discussed. © 1999 John Wiley & Sons, Inc.