Subadditivity in Memory for Personal Events

Abstract—People's subjective probability judgments of external events are often subadditive (i.e., the probability estimates of component parts of a single event sum to greater than one)—a clear violation of the extensional nature of probability theory. We show that people's frequency judgments of personal events can also be subadditive. We found subadditivity even when component events made up a proper subset of a wider composite event. Our findings imply that the somewhat arbitrary choice of the specificity with which questions are asked can produce widely different reports for the same composite events.