Echo chamber effects in social networks are generally attributed to the prevalence of interactions among like-minded peers. However, recent evidence has emphasized the role of hostile interactions between opposite-minded groups. Here, we model information propagation between such groups by generalizing popular contagion models to signed networks. We show that echo chambers spontaneously emerge in balanced networks, and in antibalanced ones for specific parameters. The robustness of our results is confirmed through simulations on various network topologies, including a real-world dataset.
