Spontaneous emergence of groups and signaling diversity in dynamic networks

We study the coevolution of network structure and signaling behavior. We model agents who can preferentially associate with others in a dynamic network while they also learn to play a simple sender-receiver game. We have four major findings. First, signaling interactions in dynamic networks are sufficient to cause the endogenous formation of distinct signaling groups, even in an initially homogeneous population. Second, dynamic networks allow the emergence of novel hybrid signaling groups that do not converge on a single common signaling system but are instead composed of different yet complementary signaling strategies. We show that the presence of these hybrid groups promotes stable diversity in signaling among other groups in the population. Third, we find important distinctions in information processing capacity of different groups: hybrid groups diffuse information more quickly initially but at the cost of taking longer to reach all group members. Fourth, our findings pertain to all common interest signaling games, are robust across many parameters, and mitigate known problems of inefficient communication.

Figure 1

Different strategies to achieve signal coordination. (a) Homogeneous signaling (top): complement strategies match. Hybrid signaling: complement strategies differ. Agents using hybrid strategies can coordinate successfully with complementary types, but they take the wrong action if interacting with themselves (red circles). (b) Homogeneous agents interact optimally with any agent using the same strategy, while hybrid agents only interact optimally with the complementary types (solid black arrows). Interactions between the hybrid types and the homogeneous types receive nonzero payoffs, but are nearly eliminated by the end of the simulation (dashed arrows).

Figure 2

Game play and updating mechanism. In each round agents must (i) select an interaction partner, (ii) earn a payoff based on the expected outcome, and (iii) update their network and strategy weights based on the payoff.

Figure 3

Emergence of Signaling Groups. (a) Example outcome from one simulation of the $2\times 2\times 2$ game using force-directed layout. Inner and outer node colors represent an agents primary sender and receiver strategy. Inset: Population starts from uniform network ties and strategy weights. Main: Population separates into three clusters: two homogeneous and one hybrid (dashed lines). Agents in the hybrid group form a bi-partite network and interact only with those of opposite type (for visual clarity links with less than 1% interaction probability are not shown). (b) Each bar represents one simulation containing 100 agents. Bars are sorted by the size of hybrid group. 87% contain a hybrid group (S1R2-S2R1) and many simulation runs contain all three groups.