The subjective dates of natural events in very-long-term memory

This research explores the problem of how people determine the time of public events, such as the attempted assassination of Ronald Reagan or the Three-Mile Island accident. According to what here is called the accessibility principle, the subjective dates of these events depend in part on the amount that can be recalled about them: The more known, the more recent the event will seem. Experiments 1 and 2 demonstrate this effect when subjects estimate explicit dates for important news stories of the 1970s and 1980s. The same effect appears in Experiment 3 for subjects who rate the recency of less known events drawn from a single week. Accessibility also contributes to the amount of time needed to compare the subjective date of an event (e.g., the Jonestown suicides) to an explicitly presented date (e.g., November 1979), as shown in Experiment 4. The accessibility principle for time estimation can be conceived as one of a related group of retrieval-based inferences that plays a part in judgments of frequency and probability and judgments about the falsity of a putative fact.