In this episode on Cognitive Decision Making & Medical Error, Dr. Doug Sinclair, CMO of St. Michael's Hospital and Dr. Chris Hicks show us that, while the ED physician's knowledge base may play a small part in predicting medical error, more important might be how we understand and reflect upon our decision-making processes, how we communicate with our staff and patients, and how we cope with the ED environment and shift work. Medical error is the 6th leading cause of death in North America, and despite huge advances in imaging technology and lab testing as well as an explosion of EM literature in recent years, the misdiagnosis rate detected through autopsy studies has not changed significantly over the past century. Studies on diagnostic error in emergency medicine have shown error rates between 1 and 12%, and it's been suggested that cognitive error, or some flaw in the decision making process (as apposed to a lack of knowledge), is present in about 95% of these cases. Dr. Sinclair and Dr. Hicks elucidate for us how to identify and understand cognitive decision making and medical error, and how we can improve our decision making, reduce medical error and optimize the care of our patients.