A revolution in psychologic research in the latter half of the 20th century upended the notion of human decision making as essentially rational, with choices driven by calculation and optimization. Rather, humans are decision makers highly influenced by how choices are framed, by their prior experience, and by many other influences not readily apparent at the time decisions are made. Decision making is particularly complex in and around care of critically ill patients, given the quantity and complexity of data being collected as well as the rapid time course of events. In addition, such patients are often incapacitated, with the added complexity that many decisions are therefore made by family members. Even when clinicians frame likely outcomes as best they can, families may be subject to optimism bias when interpreting the information.