The Right Mix of Independence and Interdependence for Group Decision Making

We have developed an agent-based model of nest-site choice among honeybees. The model not only explicitly represents the behaviour of each individual bee as a simple stochastic process, but it also allows us to simulate the bees' decision-making behaviour under a wide variety of empirically motivated as well as hypothetical assumptions. The model predicts that, consistently with empirical observations by Seeley & Buhrman (2001), the bees manage to reach a consensus on the best nest site for a large range of parameter conditions, under both more and less demanding criteria of consensus. Moreover, the model shows that the remarkable reliability of the bees' decision-making process stems from the particular interplay of independence and interdependence between them. The bees are independent in assessing the quality of different nest sites on their own, but interdependent in giving more attention to nest sites that are more strongly advertised by others.

Without interdependence, the rapid convergence of the bees' dances to a consensus would be undermined; there would not be a ‘snowballing’ of attention on the best nest site. Without independence, a consensus would still emerge, but it would no longer robustly be on the best nest site; instead, many bees would end up dancing for nest sites that accidentally receive some initial support through random fluctuations. It is only when independence and interdependence are combined in the right way that the bees achieve their remarkable collective reliability.