Imagery reduces false recognition in younger and older adults through the use of a distinctiveness heuristic

Mental imagery is well known as a technique for improving memory, yet it also aids in creating false memories (Garry, 2000). Can imagery's distinctiveness be used instead to avoid creating false memories? Four experiments are presented that provide evidence that imagery can be used to reduce false memories, even more than it can improve memory for what one has seen. Data suggest that participants use a distinctiveness heuristic to reduce their false recognition after they have been provided distinctive information at study. They expect to recollect the distinctive information, and in the absence of such recollection, properly reject nonstudied information as "new". In Experiment 1, young adults reduced source-based false recognition in a repetition lag paradigm (Dodson & Schacter, 2002b) after encoding all or half of the study items distinctively compared to a non-distinctive study condition. In Experiment 2, these findings were extended to older adults. In Experiment 3, using a categorized list paradigm where participants incidentally encoded a list of unrelated items and studied categorized lists (2005), these findings replicated the previous findings on source-based false recognition and were extended to both gist-based false recognition and gist-plus-source-based false recognition. Young adults were able to reduce all three types of false recognition when categorized lists were imagined and the incidental list was not processed distinctively. Experiment 4 examined potential reasons for high levels of source-based false recognition that had been found in a condition where participants imagined both the unrelated and categorized lists. The experiment revealed that making category structure more salient helped participants to expect to remember the categories and therefore reject non-categorized items from the unrelated list. A distinctiveness heuristic account is discussed as the explanation for the decreases in false recognition in all four studies.