This study will characterize and estimate the impact of cognitive biases – systematic human errors in decision-making – on patient and physician decisions to accept offers of life-prolonging but imperfect kidneys for transplant. Cognitive biases may interfere with the organ acceptance process, contributing to the high non-utilization rate of deceased donor kidneys in the United States and resulting in decreased survival for patients with end-stage kidney disease. Understanding how cognitive biases affect decisions to accept or decline organs will support the development of strategies to improve patient and physician decision-making and to optimize outcomes for patients awaiting transplantation.