The simulation heuristic is a psychological heuristic, or simplified mental strategy, according to which people determine the likelihood of an event based on how easy it is to picture the event mentally. Partially as a result, people experience more regret over outcomes that are easier to imagine, such as "near misses". The simulation heuristic was first theorized by psychologists Daniel Kahneman and Amos Tversky as a specialized adaptation of the availability heuristic to explain counterfactual thinking and regret. However, it is not the same as the availability heuristic. Specifically the simulation heuristic is defined as "how perceivers tend to substitute normal antecedent events for exceptional ones in psychologically 'undoing' this specific outcome." Kahneman and Tversky also believed that people used this heuristic to understand and predict other's behavior in certain circumstances and to answer questions involving counterfactual propositions. People, they believe, do this by mentally undoing events that have occurred and then running mental simulations of the events with the corresponding input values of the altered model. For example, a study was proposed that provided a group of participants with a situation describing two men who were delayed by half an hour in a traffic jam on the way to the airport. Both men were delayed enough that they both missed flights on which they were booked, one of them by half an hour and the second by only five minutes (because his flight had been delayed for 25 minutes). The results showed that a greater number of participants thought that the second man would be more upset than the first man. Kahneman and Tversky argued that this difference could not be attributed to disappointment, because both had expected to miss their flights. They believed instead that the true explanation was that the students utilized the simulation heuristic and so it was easier for them to imagine minor alterations that would have enabled the second man to arrive in time for his flight than it was for them to devise the same alterations for the first man. History This heuristic was introduced by the Israeli psychologists Daniel Kahneman (born 1934) and Amos Tversky (1937–96) in a lecture in 1979. It was published as a book chapter in 1982. Simulation different from availability The subjective probability judgments of an event, used in the simulation heuristic do not follow the availability heuristic, in that these judgments are not the cause of relevant