Are more heads more motivated than one? The role of communication in group belief updating

Many decisions are made by groups operating under uncertainty, with beliefs playing a critical role. However, little is known about how groups, often driven by self-serving motivations, aggregate these beliefs. In an experiment, we examine how groups form and update beliefs following communication. Belief updating in groups is more asymmetric (and pessimistic) but this asymmetry is not driven by self-serving motivations. Based on text analyses, risk is a prominent topic in discussions and we observe a self-serving bias in more risk-averse groups. Group decision making is a necessary but not sufficient condition for biased beliefs – group composition also matters.