The question under which conditions interacting groups have the potential to achieve group synergy has been a focal point of psychological research for decades now. More recently, Keck & Tang (2021) have demonstrated that structuring a group in such a way that one group member has the sole responsibility for the group estimate may improve the performance of interacting groups in quantitative estimation tasks. However, the specific group process which allows structured groups to create more value from interacting than consensus groups remains elusive. There seem to be two possibilities: Group-to-individual (G-I) transfer and differential weighting.

The aim of the presented study therefore is twofold: First, we test whether the main finding of Keck & Tang (2021) replicates. Second, if the effect can be replicated, we explore which specific group process may be responsible for the increased accuracy of leader groups: G-I transfer or differential weighting. To achieve this, we conduct a pre-registered online experimental study with a mixed 3x2 design, with decision-making structure (consensus vs. leadership vs. nominal) as a between-subjects factor and population bias (high vs. low bias) as a within-subjects factor. We further adjust the experimental procedure (from blocked to alternating), which allows us to control for G-I transfer, since increases in individual capability after working in a group are reflected in the individual estimates. Data collection follows a Bayesian sequential testing plan (minimum N = 300, up to N = 600) and will be completed ahead of the conference. Results will be available for presentation.