VAN HEIL AND MERVIELDE Effects of ambiguity EFFECTS OF AMBIGUITY AND NEED FOR CLOSURE ON THE ACQUISITION OF INFORMATION Alain Van Hiel and Ivan Mervielde Ghent University, Belgium The present research explores the effects of ambiguity and need for cognitive clo- sure on the acquisition of information. Experiments 1 through 3 used various operationalizations of ambiguity. It was shown that ambiguity leads to more in- formed and slower decisionmaking, but high levels of need for closure impeded this tendency to consult more information. However, Experiment 4 revealed that need for closure intensified the ambiguity effect at some time later in the judgmen- tal process. The role of ambiguity and the operation of pre- and postcrystallization processes are discussed within the theoretical framework of need for closure the- ory. Although Kruglanski and colleagues address the concept of ambiguity in parts of their theory—including the definition of the need for clo- sure—only two studies have investigated the relationship between am- biguity and need for closure. On the basis of these studies, Kruglanski and colleagues (Kruglanski, Peri, & Zakai, 1991; Kruglanski, Webster, & Klem, 1993) concluded that need for closure leads to greater information acquisition in the early phases of the knowledge acquisition process (i.e., in the precrystallization phase), whereas need for closure impedes infor- mation acquisition in later phases of this process (i.e., in the postcrystallization phase). These authors also suggest that people start the knowledge acquisition process with highly ambiguous representa- tions, and hence they seem to equate the precrystallization phase with high levels of ambiguity. Social Cognition, Vol. 20, No. 5, 2002, pp. 380-408 380 Correspondence should be addressed to Alain Van Hiel, Department of Developmental and Personality Psychology, Henri Dunantlaan 2, B-9000, Ghent, Belgium; E-mail: alain.vanhiel@rug.ac.be.