title: Heterogeneous Preference and Local Nonlinearity in Consensus Decision Making.
abstract: In recent years, a large body of research has focused on unveiling the fundamental physical processes that living systems utilize to perform functions, such as coordinated action and collective decision making. Here, we demonstrate that important features of collective decision making among higher organisms are captured effectively by a novel formulation of well-characterized physical spin systems, where the spin state is equivalent to two opposing preferences, and a bias in the preferred state represents the strength of individual opinions. We reveal that individuals (spins) without a preference (unbiased or uninformed) play a central role in collective decision making, both in maximizing the ability of the system to achieve consensus (via enhancement of the propagation of spin states) and in minimizing the time taken to do so (via a process reminiscent of stochastic resonance). Which state (option) is selected collectively, however, is shown to depend strongly on the nonlinearity of local interactions. Relatively linear social response results in unbiased individuals reinforcing the majority preference, even in the face of a strongly biased numerical minority (thus promoting democratic outcomes). If interactions are highly nonlinear, however, unbiased individuals exert the opposite influence, promoting a strongly biased minority and inhibiting majority preference. These results enhance our understanding of physical computation in biological collectives and suggest new avenues to explore in the collective dynamics of spin systems.
authors: Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.|Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey 08544, USA.
authors: Andrew T
authors: AT
authors: Hartnett
authors: UPMC Université Paris 06, Laboratoire de Probabilités et Modèles Aléatoires, CNRS UMR 7599, 75005 Paris, France.|Collège de France, Center for Interdisciplinary Research in Biology, CNRS UMR 7241, 75005 Paris, France.
authors: Emmanuel
authors: E
authors: Schertzer
authors: Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey 08544, USA.
authors: Simon A
authors: SA
authors: Levin
authors: Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey 08544, USA.|Department of Collective Behaviour, Max Planck Institute for Ornithology, D-78457 Konstanz, Germany.|Chair of Biodiversity and Collective Behaviour, University of Konstanz, D-78457 Konstanz, Germany.
authors: Iain D
authors: ID
authors: Couzin