Imagine that the U.S. is preparing for an outbreak of an unusual Asian disease that is expected to kill 600 people. Government officials have proposed two alternative programs to combat the disease. Under program A, 200 people will be saved. Under B, there is a one-third probability that 600 people will be saved and a two-thirds probability that nobody will. Confronted by this choice, 72 percent of people choose A, preferring to save 200 people for certain rather than risking saving no one.
Now imagine that officials present these two options instead: under program C, 400 people will die; under program D, there is a one-third probability that nobody will die and a two-thirds probability that all 600 people will perish. Faced with this pair of scenarios, 78 percent of people choose D, according to results of a classic study by Nobel laureate Daniel Kahneman, a psychologist at Princeton University, and his longtime collaborator, psychologist Amos Tversky.