Consistency dynamics in accusation-endorsement networks with an external judge

Abstract Previous network models have imagined that connections change to promote structural balance, or to reflect hierarchies. We propose a model where agents adjust their connections to appear credible to an external judge or observer. In particular, we envision a signed, directed network where positive edges represent endorsements or trust and negative edges represent accusations or doubt, and consider both the strategies an external judge might use to identify credible nodes and the strategies nodes might use to then appear credible by changing their outgoing edges. First, we establish that an external judge may be able to exactly identify a set of ‘honest’ nodes from an adversarial set of ‘cheater’ nodes regardless of the cheater nodes’ connections. However, while these results show that an external judge’s task is not hopeless, some of these theorems involve network structures that are NP-hard to find. Instead, we suggest a simple heuristic that an external judge might use to identify which nodes are not credible based upon their involvement with particular implicating edge motifs. Building on these notions, and analogously to some models of structural balance, we develop a discrete-time dynamical system where nodes engage in consistency dynamics, where inconsistent arrangements of edges that cause a node to look ‘suspicious’ exert pressure for that node to change edges. We demonstrate that these dynamics provide a new way to understand group fracture when nodes are worried about appearing consistent to an external judge or observer.