An activity or situation that produces conditions which are not real, but have the appearance of being real, used especially for testing something. Longman Dictionary of Contemporary English. Simulation has evolved over the centuries but has not been applied to medicine until the 20th century with the introduction of virtual reality and computers. Prior to the 20th century simulation took the forms of physical models and cadavers. With the introduction of flight simulation there was an effort to move similar approaches into medicine. This was pushed by the demands of minimally invasive surgery and the introduction of robotics in surgery. In the 21st century in addition to cognitive task analysis tools we are beginning to see the migration of advanced intelligence tools to simulation. We are just at the beginning of how we will use adversarial reasoning in the medical environment and in high risk time constrained situations like Emergency Medicine. The practitioner of emergency medicine is at high risk for errors because of multiple factors including high decision density, high levels of diagnostic uncertainty, high patient acuity, and frequent distractions. Some authors have suggested that instructing physicians in “cognitive forcing strategies” or “metacognition” will help reduce the amount of cognitive error in medical practice. It has been said ‘‘[There is an] ethical obligation to make all efforts to expose health professionals to clinical challenges that can be reasonably well simulated prior to allowing them to encounter and be responsible for similar real-life challenges.’' TYPES OF SIMULATION • Verbal • Tactile • Visual • Situational • Environmental TYPES OF SIMULATION TRAINING • Standardized patients (role play) • Basic models (partial task trainers) • Simple level • Higher level • Mannequins • Low fidelity • High fidelity • Virtual patients • Screen-based; computer-based • COMBINATIONS • Augmented sp encounters with technology • Crises management HUMAN PATIENT SIMULATION • Realistic • Suitable for all levels • Safe • Wide variety of training programs • Expensive ADVANTAGES OF SIMULATION • Patients are never at risk • Serious but infrequent events, in predictable times and places • Errors can be allowed to occur, and play-out • Rehearsal, repetition, mastery • Crisis management simulation, planning • Reduces institutional liability • Increases operational confidence • Produces rapid results • Allows team training • Increases institutional prestige The use of high fidelity simulations to train multidisciplinary teams in critical environments is well established.