Contradictory maxims such as “two heads are better than one” and “too many cooks spoil the broth” raise the question WHY people engage in collective decisions. We propose that an overlooked and very important reason to join collectives is sharing responsibility for decision outcomes. Sharing responsibility with others protects individuals from possible negative consequences of difficult and uncertain decisions by reducing regret, punishment and stress.

Motives to join a collective decision can relate to the decision process itself and its anticipated outcome. These motives include improving outcomes (combining effort and pooling intelligence, underlined); social inclusion and normative needs (in italic); and critically for us: shared responsibility (in bold). Of course, an important question is how all these different factors interact or add up to motivate people to engage in a collective decision.
We are currently running behavioral (online and in the lab) and neuroimaging experiments inspired from neuroeconomics and social psychology to empirically address questions related to this framework, for example:
We explain our proposed framework in detail in our new perspective paper (El Zein, Bahrami & Hertwig, Nature Human Behaviour). The paper is openly accessible to pubic but in case you could not find it Marwa for a copy.