Domain-selective bridging algorithm beats uniform bridging in echo chamber simulation

A new arXiv paper from researcher Masahiro Fujita argues that echo chambers are an inevitable byproduct of human cognition optimized for small-group relevance, not a flaw algorithms can simply 'fix' by pushing diverse content everywhere. Conventional calls for behavioral change are low-feasibility, he says. Instead, his paper constructs two tools: the Agenda Democratization Index (ADI), which quantifies decentralization of agenda-setting power across four variables—barrier to entry, granularity, interactivity, and feedback resolution—and a Social Information Health (SIH) model that combines ADI with bridging strength.

Fujita's proposed solution is 'domain-selective bridging.' Rather than applying a uniform bridging weight across all content, the algorithm optimizes bridging for each information domain based on variability (V) and collective scope (S). In agent-based simulations comparing three designs—no bridging, uniform bridging, and domain-selective bridging—the domain-selective approach substantially outperformed uniform bridging on SIH user satisfaction, while maintaining user experience in hobby and lifestyle domains. That means more information sharing in domains relevant to collective decision-making (like politics or health) without ruining the feed for entertainment. The paper reframes the echo chamber debate from normative opposition to an engineering design task: which domains, at what degree, and through what algorithm design should bridging be implemented.