Abstract

each trial. That model was rejected because it out-performed the dyads in experiment 2. This leaves open the possibility that the participants did com-municate contrast and reliability, but used that information suboptimally, which seems unlikely, as we never observed any dyads explicitly com-municating contrast and reliability separately. However, our data cannot definitively rule out this idea, and further research is needed to dis-tinguish between optimal use of WCS versus suboptimal DSS. The general consensus from extensive earlier work on collective decision-making is that groups rarely outperform their best members (11, 15). Even in one of the rare cases in which consistent