Context memory and the selection of frequency estimation strategies.

When people estimate event frequency, they sometimes retrieve and count event instances. This study demonstrates a direct relation between the use of these enumeration-based strategies and the contents of memory. In 3 experiments, participants studied target-context word pairs, estimated presentation frequency for target words, and recalled context words. Study time, target-context relatedness, and study-phase instructions were manipulated, producing large differences in memory for context words. When context memory was best, estimation time increased sharply with presentation frequency, and the steepness of this estimation time-presentation frequency function decreased with context memory. These results indicate that enumeration was common only when context memory was good, that encoding factors determine how frequency is represented, and that the contents of memory restrict strategy selection.