Belief updating frictions and delayed trade in bilateral markets with heterogeneous beliefs a dynamic model with bilateral viscosity and heterogeneous updating rules

Abstract This paper studies how heterogeneity in belief updating generates coordination failures in bilateral markets, even when information is symmetrically available. We develop a formal dynamic model in which seller and buyer update beliefs via exponentially weighted moving averages governed by viscosity parameters κS, κB ∈ (0,1). The interaction between agents with different updating speeds produces endogenous trading delays and deadweight losses that exceed those predicted by either agent’s friction alone. The coordination gap Gt=κSᵗ·α+κBᵗ·β-δ integrates both dynamics in a single tractable expression. We derive four propositions on permanent coordination failure, trading delay T*, the amplifying effect of epistemic heterogeneity (κS≠κB), and deadweight welfare loss. We then endogenize κ through a cognitive-cost minimization framework linked to rational inattention, deriving comparative statics on how κ* responds to stakes, cognitive costs, and initial biases. A quantitative calibration to a real estate market benchmark (α = 10%, β = 7.5%, δ = 4% of asset value) yields realistic trading delays of 3-15 quarters and deadweight losses of 12-54% of the gains-from-trade depending on κ. Policy simulations show that combining 30% bias reduction with a 5-percentage-point decrease in κ recovers 42% of the welfare loss. An organizational extension shows collective viscosity κorg grows super-linearly with hierarchical layers, linking firm-level coordination failure to individual belief-updating inertia. These results suggest that coordination failures may persist even under high transparency when agents differ in belief-updating speeds. JEL Classification: D82 · D83 · D91 · C73