Optimal use of limited cognitive resources produces bias and noise in medical decisions

Medical providers make more errors under cognitive load, often viewed as arising from suboptimal decision-making. This interpretation relies on frameworks that ignore cognitive costs. Here, we offer a fundamentally different perspective that reveals an underlying structure to medical errors: bias (systematic deviations) and noise (variability) are inevitable consequences of optimal decision-making under cognitive resource constraints. We analyze orders placed by emergency department providers and find that cognitive load increases bias and noise, consistent with the optimal allocation of resources. Because providers near-optimally adjust to cognitive demands, this argues that guidelines that increase cognitive resources are necessary to reduce errors. Consistent with this perspective, bias and noise are minimized when multiple providers contribute to patient care. These findings have implications for optimizing medical care.