Behavioral Drivers of Supply Chain Instability: Exploring the Roles of Supply Line Underweighting and Trust

In modern supply chains, not only the external disruptions, but also the behavioral causes significantly contribute to supply chain instabilities, particularly through the misperception of delayed feedback. This research co-evaluates how two behavioral mechanisms, supply line underweighting and trust, shape instability in supply chains. Using a System Dynamics simulation model based on the canonical Beer Game, the study examines how managers underestimate inventory already in transit while simultaneously adjusting their trust in suppliers through operational feedback and policy assumptions. The findings reveal that supply line underweighting acts as a dominant behavioral amplifier, generating severe inventory oscillations, order amplification, and delayed recovery even under stable operating conditions. In contrast, trust mainly alters the intensity of fluctuations rather than the underlying system behavior. By integrating cognitive bias and relational dynamics within a single feedback-driven framework, this research advances behavioral supply chain theory and provides insights into designing more resilient and behaviorally informed supply chain policies under uncertainty.