In Brief

By remembering every item on a list, people can effectively limit their tendency to falsely recognize words, according to a new study in the January Journal of Experimental Psychology: Learning, Memory and Cognition (Vol. 29, No. 7). The study explores meta-cognitive methods for distinguishing true memories from false ones and adds to psychologists' understanding of memory processes, says David Gallo, PhD, a postdoctoral research fellow at Harvard University.

Gallo used timed computer displays to teach 96 undergraduate students lists of words, such as "basil, oregano, pepper," and "starling, robin, sparrow." The words were presented individually, but grouped by category. Some participants learned lists with fixed numbers of words per category while other participants read a different number of examples for each group. After a waiting period in which participants worked on an unrelated task, the participants then determined whether particu-lar words were new or previously studied.

In the fixed-length condition, participants performed better at discriminating between new and previously learned words, because, according to Gallo, they had memorized the complete list of words, a strategy Gallo terms "disqualifying recall-to-reject."

Disqualifying memory-evaluation depends on remembering facts inconsistent with false memories, he says. In this case, a person might reason that the presented word did not occur before by comparing it with the complete list of remembered words. Participants were able to recall the complete list of words when they knew how many words were on the original list, and were therefore able to tap this strategy. Gallo also found that while explicit instructions were helpful, they were not necessary to prompt participants to use this strategy.

However, when the number of words for each category varied, participants found it difficult to use disqualifying recall-to-reject and instead fell back on diagnostic recall-to-reject, a process in which people compare the memory of an event known to have happened with the qualities, such as vividness, of a questionable memory. In this case, a participant might visualize the test word on the computer screen, focusing on its position and brightness, and make comparisons to words definitely remembered.

Gallo found that in the study's particular memory task, diagnostic memory strategies did little to aid participants in distinguishing learned words from new ones. When participants attempted to compare the qualities of questionable memories with ones they were certain of, they responded with many false memories.

"This is not to say [diagnostic memory strategies] never work--we know they do," Gallo says. "Instead, this study shows that there are different ways that recall can reduce false memories, and their utility will depend on the particular task or situation."