The Effect of Discussion upon the Correctness of Group Decisions, When the Factor of Majority Influence Is Allowed for

1937 ◽  
Author(s):  
Robert L. Thorndike
2008 ◽  
Author(s):  
Michel Handgraaf ◽  
Philip Schuette ◽  
Nicole Yoskowitz ◽  
Elke Weber ◽  
Kerry Milch ◽  
...  
Keyword(s):  

Author(s):  
Sascha Meyen ◽  
Dorothee M. B. Sigg ◽  
Ulrike von Luxburg ◽  
Volker H. Franz

Abstract Background It has repeatedly been reported that, when making decisions under uncertainty, groups outperform individuals. Real groups are often replaced by simulated groups: Instead of performing an actual group discussion, individual responses are aggregated by a numerical computation. While studies have typically used unweighted majority voting (MV) for this aggregation, the theoretically optimal method is confidence weighted majority voting (CWMV)—if independent and accurate confidence ratings from the individual group members are available. To determine which simulations (MV vs. CWMV) reflect real group processes better, we applied formal cognitive modeling and compared simulated group responses to real group responses. Results Simulated group decisions based on CWMV matched the accuracy of real group decisions, while simulated group decisions based on MV showed lower accuracy. CWMV predicted the confidence that groups put into their group decisions well. However, real groups treated individual votes to some extent more equally weighted than suggested by CWMV. Additionally, real groups tend to put lower confidence into their decisions compared to CWMV simulations. Conclusion Our results highlight the importance of taking individual confidences into account when simulating group decisions: We found that real groups can aggregate individual confidences in a way that matches statistical aggregations given by CWMV to some extent. This implies that research using simulated group decisions should use CWMV instead of MV as a benchmark to compare real groups to.


1972 ◽  
Vol 34 (1) ◽  
pp. 15-25
Author(s):  
Marcia Guttentag ◽  
Gloria Wheeler

Group effects on individual inferences were studied to determine whether risky shifts in individual judgments would follow group decisions. Ss were asked to make likelihood ratio estimations in a non-cumulative condition and cumulative odds estimates in another condition. Ss were either in individual followed by group conditions or the reverse. Both natural and ad hoc 5-person groups were used. The normative model provided by Bayes' theorem was used to examine groups with effects on individual judgments. Natural and ad hoc groups did not differ. Noncumulative likelihood-ratio groups were veridical compared with the normative model. Although cumulative odds group were conservative in their judgments, no systematic shifts in a risky or conservative direction were found for either task. The group had an anchoring or conformity effect on later judgments of individuals, but this effect was not in the direction of veridicality.


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