Preference-consistent evaluation of information 1 Running Head: PREFERENCE-CONSISTENT EVALUATION OF INFORMATION Effects of Consensus Information and Task Demonstrability on Preference-Consistent Information Evaluation and Decision Quality in Group Decision Making

Groups often fail to solve hidden profiles even when all information is exchanged. This is partly due to biased evaluation of information. We examined the effects of consensus information and task demonstrability on preference-consistent information evaluation and decision quality. The results showed that the evaluation of unshared but not shared information was moderated by consensus information and task demonstrability. For unshared information, majority members exhibited a higher evaluation bias favoring preferenceconsistent information than minority members. Task demonstrability reduced the evaluation bias only when group members received no information about the other members’ preferences. Finally, majority members were less likely to solve the hidden profile than minority members, and this was partially mediated by the evaluation bias favoring preference-consistent unshared information. Preference-consistent evaluation of information 3 Effects of Consensus Information and Task Demonstrability on Preference-Consistent Information Evaluation and Decision Quality in Group Information Pooling Hidden profiles are group decision tasks in which a correct choice alternative exists, but no group member can detect this alternative based on his or her individual information set prior to the discussion (Stasser, 1988). This is due to the distribution of unshared information across group members. In a hidden profile, unshared and shared information point to different decisions, and the alternative implied by the unshared information is the correct one (relative to the entire information set available to the group). Hence, groups can only detect the correct decision by pooling the unshared information. Although hidden profiles are prototypical tasks in which groups can outperform individual decision-makers, research has shown that groups frequently fail to solve hidden profiles (for reviews, see Mojzisch & Schulz-Hardt, 2006; Stasser & Birchmeier, 2003). Two group-level processes have been identified that account for this failure: First, groups fail to exchange the critical unshared information during discussion (Stasser & Titus, 1985). Second, even if group members discuss sufficient unshared information, they do not give much weight to what is discussed but focus rather on negotiating the weighting of their prediscussion preferences (Gigone & Hastie, 1993). Preference-consistent evaluation of information during group information pooling Recent evidence suggests that group-level processes do not fully account for the failure of groups to solve hidden profiles. Even if all information is discussed, the solution of hidden profiles is hampered by the group members’ tendency to stick to their suboptimal preferences (Faulmüller, Kerschreiter, Mojzisch, & Schulz-Hardt, 2010; Greitemeyer & Schulz-Hardt, 2003). This tendency is due to biased evaluation of information. In a hiddenprofile, the critical unshared information (which is required to be exchanged in order to solve Preference-consistent evaluation of information 4 a hidden profile) is typically inconsistent with the group members’ initial preferences. Since preference-consistent information is judged to be more important and compelling than preference-inconsistent information, group members individually tend to stick to their suboptimal preferences and, hence, fail to solve the hidden profile in the group. Therefore, even if all unshared pieces of information are exchanged during discussion, preferenceconsistent evaluation of information fosters the maintenance of the initial incorrect preference and hence hampers the solution of a hidden profile. In the experiments by Greitemeyer and Schulz-Hardt (2003), participants first received information about three alternatives and were asked to indicate their preference. The information was either representative of the entire information set (manifest profile) or not representative (hidden profile). Next, participants received a transcript of a fictitious discussion, containing full information about the alternatives. Participants had to reach a final decision after having studied the transcript. For each item of information, participants had to rate its importance, credibility, and valence. As predicted, most participants failed to solve the hidden profile. Preference-consistent information was evaluated more favorably than preference-inconsistent information (both in the hidden profile and in the manifest profile condition), and this evaluation bias mediated the tendency of individuals to stick to their initial incorrect preferences. Thus, preference-consistent information evaluation works against the solution of hidden profiles even if all information is exchanged. An important lesson that can be learned from this result is that in order to help groups to solve hidden profiles we need to know which variables moderate preference-consistent evaluation of information during group decision-making. Over the last two decades, many studies have focused on the question which variables moderate the exchange of information. In contrast, the question which variables moderate the evaluation of the information Preference-consistent evaluation of information 5 exchanged has been largely neglected. Therefore, the primary aim of the present study was to investigate this issue. Consensus information and the Consensus implies Correctness Heuristic Previous research has found that the distribution of pre-discussion preferences has a strong impact on information exchange and group decision-making (e.g. Brodbeck, Kerschreiter, Mojzisch, Frey, & Schulz-Hardt, 2002; Hollingshead, 1996; Mojzisch & Schulz-Hardt, 2010; Scholten, Van Knippenberg, Nijstad, & De Dreu, 2007; Schulz-Hardt, Brodbeck, Mojzisch, Kerschreiter, & Frey, 2006). So far, however, we do not know whether consensus information (i.e., information about the extent to which the other group members share one’s decision preference) also influences the evaluation of the information exchanged during discussion. But why should consensus information affect preference-consistent evaluation of information? According to research by Chaiken and Stangor (1987), individuals follow a consensus implies correctness heuristic in decision making. This heuristic can be summarized as follows: If many people have come to prefer the same alternative, it is likely to be the better one. Hence, when people learn that their fellow group members have come to the same conclusion (majority feedback) this should make them more convinced about the correctness of their choice. Since confidence in the correctness of one's choice has been found to increase preference-consistent processing of information (Brannon, Tagler, & Eagly, 2007; SchulzHardt, Frey, Lüthgens, & Moscovici, 2000), majority feedback should increase preferenceconsistent evaluation of information. In other words, majority members should exhibit a higher evaluation bias favoring preference-consistent information than minority members. Moreover, we assume that, in general, consensus information has a stronger effect on the evaluation of unshared information than on the evaluation of shared information. Since shared information, by definition, is evaluated before individuals learn about their fellows Preference-consistent evaluation of information 6 group members’ preferences, whereas most of the unshared items are encountered for the first time during the discussion, it is plausible that consensus information has less impact on the evaluation of shared information than on the evaluation of unshared information. So far, only two studies have tested whether consensus information affects group members’ biased evaluation of information, but both studies have important methodological shortcomings. The first study (Greitemeyer & Schulz-Hardt, 2003) found evidence for the impact of biased evaluation of information on decision quality, but did not find any effect of consensus information on biased evaluation of information. However, the failure to find any effect of consensus information may have been due to the fact that participants were not led to believe that they would interact with real fellow group members. Instead, participants received a transcript of a fictitious discussion, with fictitious group members as protagonists. The second study (Van Swol, 2007) employed face-to-face interacting groups and found that minority members rated preference-inconsistent information as more important than majority members did. However, this study did not control for which items of information were pooled during discussion, nor did it examine the impact of consensus information on decision quality. Therefore, it was not possible to test whether the impact of consensus information on the solution of hidden profiles is at least partially mediated by preference-consistent evaluation of information. Summing up, our first hypothesis is that consensus information has a stronger effect on the evaluation of unshared information than on the evaluation of shared information. Second, we hypothesize that majority members exhibit a higher evaluation bias favoring preference-consistent unshared information than minority members. Our third hypothesis is that majority members will be less likely to solve hidden profiles, a tendency which is mediated by biased evaluation favoring preference-consistent unshared information. Task Demonstrability Preference-consistent evaluation of information 7 According to Laughlin (1980), problem solving and decision-making tasks can be ordered on a continuum anchored by intellective and judgmental tasks. Intellective tasks are "problems or decisions for which there exists a demonstrably correct answer within a verbal or mathematical conceptual system", whereas judgmental tasks are "evaluative, behavioral, or aesthetic judgments for which there does not exist a demonstrably correct answer" (Laughlin & Ellis, 1986, p. 177). In the case of intellecti