2008, Lu, Jinhu, Liu, Jing, Couzin, Iain D., Levin, Simon A.

Many animal groups routinely make consensus decisions jointly with all group members. This paper builds a novel model merging the locally neighboring reciprocal action and alignment together to investigate the mechanisms of consensus decision-making and its robustness. Our model reveals that the shapes of the coherent flocks are limited in a common narrow interval for different group sizes and information structures. Moreover, the coherent groups display a surprising degree of tolerance against errors, however, they simultaneously show an extremely fragile to attacks. Our model and approach discover some novel phenomena and also reveal some underlying mechanisms of the consensus decision-making and its robustness in biological systems.

2006, Nabet, Benjamin, Leonard, Naomi E., Couzin, Iain D., Levin, Simon A.

We present a low-dimensional, continuous model of a multi-agent system motivated by simulationstudies on dynamics of decision making in animal groups in motion. Each individual moves at constant speed inthe plane and adjusts its heading in response to relative headings of others in the population. Two subgroupsof the population are informed such that individuals in each subgroup have a preferred direction of motion.The model exhibits stable solutions corresponding to compromise by individuals with conflicting preferences.We study the global phase space for the proposed model by computing equilibria and proving stability andbifurcations.