Rudolf Kerschreiter, Stefan Schulz-Hardt, Andreas Mojzisch, and Dieter Frey (2008)

Biased information search in homogeneous groups: Confidence as a moderator for the effect of anticipated task requirements

Personality and Social Psychology Bulletin, 34(5):679-691.

Examines whether groups united in opinion solely search for information confirming their beliefs irrespective of the anticipated task or whether they are sensitive to the usefulness of new information. In Experiment 1a, 152 German trainee sergeants (all male, aged 19-24 years) divided into 44 homogenous (similar decision preferences) groups participated. In Experiment 1b, 123 high school students (aged 16-18 years) divided into 41 homogenous (similar decision preferences) groups participated. The experimental design of both experiments is based on a 2 (anticipated group task: justify the decision vs refute counterarguments) x 2 (type of information: supporting vs conflicting) factorial design with repeated measurement on the 2nd factor. In Experiments 1a, 1b, and 2, 50 percent of the groups were given the impression that justification of their decisions would have to be given while the other groups believed they would have to refute counterarguments. The goal of Experiment 2 (99 college students aged 18-20 years) was to provide a more rigorous test of the idea that task sensitivity of homogeneous groups' information search depends on the groups' confidence in the correctness of their decision. Participants were divided into 33 homogenous (similar decision preferences) groups (1 group was subsequently excluded from analysis). Experiment 2 was based on a 2 (group confidence: high vs moderate) x 2 (anticipated group task: justify the decision vs refute counterarguments) x 2 (type of information: supporting vs conflicting) factorial design with repeated measurement on the 3rd factor. In Experiment 3, individual confidence in participants' capability to reach an optimal decision was successfully manipulated to instill either high confidence or moderate confidence. Results show that task sensitivity depends on the groups' confidence in the correctness of their decision. When expected to support a decision, moderately confident groups displayed a strong confirmation bias while exhibiting balanced information search, even seeking out counterarguments in preparation to support their chosen standpoint. Highly confident groups demonstrated a strong confirmation bias independent of the anticipated task requirements. It is concluded that heterogeneous groups should be beneficial for group performance when group performance benefits from adapting the group information search to the varying task requirements.

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