The more the merrier? : understanding the effect of group size on collective intelligence

Abstract

This dissertation explores how group size affects collective intelligence. It is composed of three quantitative studies. The first study explores how time pressure in small groups (size 4) and large groups (size 20) affected collective intelligence. The results showed that the large groups significantly and consistently outperformed the small groups in different time pressure conditions. This led to the second study which explored whether the collaboration tool used in the first study might have provided unexpected benefits for large groups that counteracted any process loss in the large groups. While the results from the second study confirmed that the collaboration tool did indeed significantly improve the collective intelligence score of groups, one surprising result was that this effect occurred, not only in large groups (size 20), but also in small ones (size 4). The final study then set out to explore this surprising result in further detail by including a variety of group sizes (sizes 5, 10, 15, 20, 25, 30, 35 and 40) in both the collaboration conditions. It was hypothesized that by including more group sizes, the study would determine whether a curvilinear (inverted-U) relationship existed. The results not only confirmed the curvilinear (inverted-U) relationship but also suggested an optimal group size of about 30 for groups with the collaboration tool and 25 for groups without the collaboration tool.