The simulation heuristic is a mental strategy where a person determines the likelihood of an event actually happening based upon how easy it is to mentally picture that event happening. The simulation heuristic was first theorized by the psychologists Daniel Kahneman and Amos Tversky as being a special type of adaptation of the availability heuristic, which was used to explain counterfactual thinking and regret.
Kahneman, D., Tversky, A. (1998). “The simulation heuristic”. In Kahneman, D., Slovic, P., Tversky, A. (1998) “Judgment under Uncertainty: Heuristics and Biases“. Cambridge: Cambridge University Press. ISBN 9780521284141.