The Probabilities of Unique Events
Abstract
Many theorists argue that the probabilities of unique events, even real possibilities such as President Obama's re-election, are meaningless. As a consequence, psychologists have seldom investigated them. We propose a new theory (implemented in a computer program) in which such estimates depend on an intuitive non-numerical system capable only of simple procedures, and a deliberative system that maps intuitions into numbers. The theory predicts that estimates of the probabilities of conjunctions should often tend to split the difference between the probabilities of the two conjuncts. We report two experiments showing that individuals commit such violations of the probability calculus and corroborating other predictions of the theory, e.g., individuals err in the same way even when they make non-numerical verbal estimates, such as that an event is highly improbable.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 30, 2012
- Accession Number
- ADA568559
Entities
People
- Max Lotstein
- Phil Johnson-laird
- Sangeet S. Khemlani
Organizations
- United States Naval Research Laboratory