Peak–end rule end. The effects of the duration of an experience upon retrospective evaluation are extremely slight. Fredrickson and Kahneman labeled this phenomenon "duration neglect". The peak–end rule is applicable only when an experience has definite beginning and end periods. A 1993 study titled "When More Pain Is Preferred to Less: Adding a Better End" by Kahneman, Fredrickson, Charles Schreiber, and Donald Redelmeier provided groundbreaking evidence for the peak–end rule. Participants were subjected to two different versions of a single unpleasant experience. The first trial had subjects submerge a hand in 14 °C water for 60 seconds. The second trial had subjects
Two-man rule captain left to use the toilet. Two-man rule The two-man rule, also known as the four-eyes principle, is a control mechanism designed to achieve a high level of security for especially critical material or operations. Under this rule all access and actions require the presence of two authorized people at all times. Per US Air Force Instruction (AFI) 91-104, "the two-person concept" is designed to prevent accidental or malicious launch of nuclear weapons by a single individual. In the case of Minuteman missile launch crews, once a launch order is received, both operators must agree that it is valid by