July 29, 2003 MEDFORD/SOMERVILLE, Mass. – As an eyewitness sits on the stand in a courtroom recalling details of an incident, how much of what he or she remembers actually happened?
False memories are a common occurrence in the courtroom and in everyday life, and have long been considered by psychologists as a side effect of efforts to boost memory. New research from Tufts University has answered the question of how to increase memory, without also increasing corresponding false memories.
"The better we understand false memory, the more we will be able to explain the factors that lead to the problem in the laboratory and real world situations," explained Tufts University psychologist Salvatore Soraci, whose research is published in July's issue of Journal of Experimental Psychology: Learning, Memory and Cognition. "Generative learning holds the promise of immunizing people against the pitfalls of false memory."
Previous research has focused on how to improve memory using "generative learning" -- the concept that individuals remember things better when actively involved in forming an idea. For example, if an individual is given a clue and asked to provide a one-word answer, he or she will remember that word better than if simply given the word and told to memorize it.
Funded by a $654,000 grant from the National Institutes of Health (NIH), Soraci and Tufts assistant professor of psychology Michael Carlin set out to determine what effect generative learning had on the formation of false memories.
According to Soraci, test participants were given a list of words to memorize – some of the words were complete, and others were missing one letter. The complete words fit within subject categories (for instance, "queen," "moat," "knight," etc.), while the incomplete words were in different subject categories (for instance, furniture such as "t_ble" and "cha_r"). After a three-minute period, during which participants were given a "distracting" math quiz, they were then presented with a list of words. This list included some words that had not been included in the original list but were related to the subject categories, and the participants were then asked if the words were among those that had been shown earlier.
"The incomplete words led to generative learning, since the participants had to determine the words on their own," Soraci said. "People were far more likely to falsely remember words from the list of complete words - such as mistakenly believing that 'king' had been on the list - than they were to falsely identify a word from the generative learning list."
In a similar experiment, test participants were not provided with the second list, and instead asked to write down all the words they could remember seeing. The experiment showed the same advantage for generative learning.
In yet another experiment, Soraci determined what kind of cues would help people to remember words without increasing false memories. Participants were given a list of words that were missing one letter and could be either of two words, depending on what letter filled in the blank. For example, one of the words on the list was "s_eaker," which could be "speaker" or "sneaker." Some of the participants were given a positive clue, such as "a tennis shoe," and asked to fill in the blank. Others were given a negative clue, such as "not part of a stereo." Soraci found that people were more likely to remember words when given a negative clue than a positive one, and were also less likely to falsely remember a word.
"This method of learning using negative cues is similar to how we find our way when we're driving our cars and looking for a new location," explained Soraci. "If we make a wrong turn, we're much more likely to remember the correct route next time by remembering that we shouldn't go the wrong way again."
Soraci's cognitive psychology research also includes his highly regarded work examining the enhancement of memory as a result of sudden realizations, or "eureka" moments. Other Soraci research focuses on the relationship between cognitive and perceptual variables -- that is, how what we see influences what we think, and conversely how our thought processes influence our concept of what we see. Soraci has worked collaboratively on several NIH research grants with the Eunice Kennedy Shriver Center, including a recent two-year $140,000 NIH grant to continue his research on generative learning and false memory on individuals who are mentally retarded.
His research also reflects Tufts' growing expertise in the field of cognitive psychology, ranging from the impact of music on the brain to the subconscious influences of stigma and stereotyping on human behavior.
"We've got a brand new psychology building outfitted with state-of-the-art labs, and Sal and his colleagues are now extending their scholarship in some innovative collaborations across the University," said Jamshed Bharucha, provost and senior vice president, who also has a cognitive psychology lab in the new facility.
Tufts University, located on three Massachusetts campuses in Boston, Medford/Somerville, and Grafton, and in Talloires, France, is recognized among the premier research universities in the United States. Tufts enjoys a global reputation for academic excellence and for the preparation of students as leaders in a wide range of professions. A growing number of innovative teaching and research initiatives span all Tufts campuses, and collaboration among the faculty and students in the undergraduate, graduate and professional programs across the University's eight schools is widely encouraged.
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