Analysis of Group Performance in Visual Signal Detection

摘要

This study analyzed how a group S decision making performance compared to thepredicted performance of a statistically optimal group on a visual signal detection task. The task has to decide, either individually or as a group, whether a stimulus display screen (composed of nine independent information sources) was representative of one of two possible normal distributions (signal or noise). Eight subjects were tested individually and as members of different sized groups. Sorkin and Dai's 1994 model of the Ideal Group was used to analyze the accuracy of group performance (d'grp). Consistent with the model of the Ideal Group, d' grp increased with the number of group members, but decreased with inter-member correlation and task difficulty. The group decision process was assumed to be based on the group assigning different weights (emphasis) to each group members' input. Overall efficiency, a relative measure of actual performance compared to ideal performance, was relatively high for two-member groups but decreased as the group grew larger. Group weighting strategies appeared to be somewhat variable for the condition in which all sources of information presented to the members were equally valid. However, when the sources of information were unequal, the group appropriately assigned more weight to the group members with the more reliable information. Some interesting social interaction phenomena were theorized to take place during the group decision process. Social loafing, coordination loss and outgoingness were examined as possible reasons for changes in group performance. Interestingly, the subjects received more weight when they acted as the spokesperson for the group compared to when they did not respond for the group.