False Memories

Mindfulness meditation is associated with various positive benefits, one of which is improved attention, but it might not be all good. A new study suggests that it may have negative cognitive consequences.

The study included three experiments, in the first two of which undergraduates carried out a 15-minute guided exercise: one group was instructed to focus attention on their breathing without judgment (mindfulness group); the other group was told to think about whatever came to mind (mind-wandering group; the control).

In the first experiment, 153 participants then studied a list of 15 words related to the concept of trash, but not including the word "trash". When then asked to recall as many of the words from the list as they could remember, 39% of the mindfulness group falsely recalled seeing the word "trash" on the list compared to only 20% of the mind-wandering group. There was no difference between the groups in the number of other words falsely recalled.

In the second experiment, 140 participants were compared to themselves, before and after the intervention. They all began by doing six of the same sort of word lists. They were then randomly assigned either the meditation exercise or the mind-wandering. This was then followed by a further six word lists.

Again, mindfulness participants were more likely to falsely recall the critical word than those who engaged in mind wandering. Those in the mind-wandering group showed no difference in performance on the word lists before and after, while those in the meditation group were significantly more likely to falsely remember the critical item. Again, there were no other differences in performance between the groups: they correctly recalled about the same number of words, and they falsely remembered about the same number of other words.

In the third experiment, 215 undergraduates had to determine whether a word had been presented earlier, where the words shown were all part of a strongly associated pair (e.g., foot-shoe). After seeing the 100 words (for 1.5 seconds each), they were then tested. Each word had an equal chance of being one of the words in the presented list, or its associated pair. All students were then given the 15-minute meditation exercise, before going through the process again.

Again, the rate of words correctly identified as seen before was about the same before and after the meditation exercise, but the rate of words falsely identified increased significantly after the exercise.

In all, then, it seems that mindfulness meditation increased participants' susceptibility to false memories, reducing their ability to differentiate items they actually encountered from items they only imagined (because of their strong association to the items encountered).

The researchers speculate that the mechanism that seems to underlie the benefits of mindfulness — judgment-free thoughts and feelings — might also affect people's ability to determine the origin of a given memory (source memory), because they have become less able to distinguish between externally occurring events and internally generated events.

Source memory is one of those memory domains that tend to be affected by aging. However, the benefits of meditation for improving attention — another area particularly affected by age — outweigh this downside. So I'm certainly not suggesting anyone should be put off by this finding!

An interesting question that remains to be answered is whether this negative effect on source memory is short-lived, or whether experienced meditators tend to have poorer source memory.

http://www.eurekalert.org/pub_releases/2015-09/afps-mmm090915.php

Findings that children are less likely than adults to distort memories when negative emotions are evoked has significant implications for the criminal justice system. Experiments involving children aged seven and 11, and young adults (18-23) found that when they were shown lists of closely related emotional words (e.g. pain, cut, ouch, cry, injury), they would tend to mistakenly remember a related word (e.g. hurt) although it had not been present. Despite the prevailing theory that being involved in a very negative experience focuses your mind and helps you notice and remember details, words that had negative emotional content produced the highest levels of false memory. With arousal (such as would be evoked in a traumatic experience), memory was distorted more. These tendencies increased with age.

When we tell people about things that have happened to us, we shape the stories to our audience and our purpose. The amount of detail we give and the slant we give to it depends on our perceptions of our audience and what we think they want to hear. Does this change our memory for the event? Certainly we are all familiar with the confusion we get after we have been telling a particular story for years — we’re no longer sure what really happened and what we’ve added or subtracted to make a better story.

There is a popular misconception that dramatic public events such as earthquakes, the Challenger disaster, JFK’s assassination, etc, are given a special status in memory (“flashbulb memories”). It is true that people often have very clear memories of these events, but research has shown that such memories are as likely as any other event memory to be inaccurate1. Vividness, I regret to say, is no reliable measure of the accuracy of a memory.

This study used two invented stories rich in detail that could be told from more than one point of view. After studying one or other of the stories, subjects were asked to write a letter about one of the characters, the letter to be biased either for or against the character. Control subjects were simply asked to write as much as they could remember about the specified character. Subjects were later tested on their recall of the original story. Different aspects of memory were investigated in a series of four experiments.

It was found that subjects who wrote the biased letters recalled more information about the specified character that was related to the biased perspective. Their recall of the other character in the story was unaffected. They also added more (erroneous) details about the character — these errors being consistent with the particular bias they’d been given.

Although selective rehearsal (the fact that these subjects had had an opportunity to rehearse the information that supported the appropriate bias, at the expense of other information) plays a part in this, biased memory was found even when the subjects, in the fourth experiment, were asked to write a biased evaluation instead of a biased retelling (to avoid rehearsal of specific items).

The slant we give to information guides our encoding of the memory, the way we organize it, and the connections we make to other memories.

References

1. Neisser, U. & Harsch, N. 1992. Phantom flashbulbs: False recollections of hearing the news about Challenger. In E. Winograd & U. Neisser (eds.) Affect and accuracy in recall: Studies of 'Flashbulb Memories'. New York: Cambridge University Press.

Larsen, S.F. 1992. Potential flashbulbs: Memories of ordinary news as the baseline. In E. Winograd & U. Neisser (eds.) Affect and accuracy in recall: Studies of 'Flashbulb Memories'. New York: Cambridge University Press.

Tversky, Barbara & Marsh, Elizabeth J. 2000. Biased retellings of events yield biased memories. Cognitive Psychology, 40, 1-38.

Older news items (pre-2010) brought over from the old website

Brain wiring creates false memories

We know how easily we can form false memories, but now a new study reveals why some people more easily form these than others. The study had 48 students read lists of semantically related words in which one word which belonged there was absent. They were then asked to recall as many of the words as they could. Those who recalled more of the absent words, and thus assumed to be more prone to false memories, were found to have higher-quality white-matter connections in the superior longitudinal fascicle (which connects frontoparietal structures, and is associated with gist-based learning), while those who were more accurate had higher-quality white-matter connections in the inferior longitudinal fascicle (the major connective pathway of the medial temporal lobe). The findings indicate that individual differences in white matter microstructure underlie true and false memory performance.

Fuentemilla, L. et al. 2009. Individual Differences in True and False Memory Retrieval Are Related to White Matter Brain Microstructure. The Journal of Neuroscience, 29(27), 8698-8703.

http://www.newscientist.com/article/mg20327164.800-brain-wiring-creates-false-memories.html

Eyewitness memory even more vulnerable than expected

We know how easy it is to distort someone’s memory of an event by providing false information, but it’s always been thought that getting people to recall what happened immediately after the event would provide some protection from the misinformation effect. Now a new study has found that those who took a recall test immediately after watching an episode of “24” were in fact more vulnerable to misinformation that was later provided. In fact, they were twice as likely to remember false information that was given after the test compared to those who weren’t given the immediate test. It’s suggested that recently recalled information is particularly vulnerable to distortion.

Chan, J.C.K., Thomas, A.K. & Bulevich, J.B. 2009. Recalling a Witnessed Event Increases Eyewitness Suggestibility: The Reversed Testing Effect. Psychological Science, 20 (1), 66-73.

http://www.physorg.com/news152378697.html
http://www.eurekalert.org/pub_releases/2009-01/afps-dis012809.php

Brain region involved in false memories identified

We’re all susceptible to false memories, but brain damage can produce false memories beyond the normal level. The pathological production of false memories is known as confabulation, and because the patients who suffer this have showed damage to various parts of the brain, the cause has been unclear until now. But a new study of 50 patients has found the common element: all those who confabulated shared damage to the inferior medial prefrontal cortex.

Turner, M.S. et al. 2008. Confabulation: Damage to a specific inferior medial prefrontal system. Cortex, 44 (6), 637-648.

http://www.eurekalert.org/pub_releases/2008-05/e-wym052808.php

Brain waves distinguish false memories from true

An imaging study of 52 neurosurgical patients being treated for drug-resistant epilepsy has found that a fast brain wave, known as the gamma rhythm, increased when participants studied a word that they would later successfully recall. The same gamma waves also increased in the half-second prior to participant’s correctly recalling an item. In other words, the gamma waves predicted whether or not an item that was about to be recalled was previously studied.

Sederberg, P.B. et al. 2007. Gamma Oscillations Distinguish True From False Memories. Psychological Science, 18 (11), 927–932.

http://www.eurekalert.org/pub_releases/2007-10/uop-prp102307.php

Brain activity distinguishes false from true recollection

Although memory confidence and accuracy tend to be positively correlated, people sometimes remember with high confidence events that never happened. A new imaging study reveals that, in cases of high confidence, responses were associated with greater activity in the medial temporal lobe when the event really happened, but with greater activity in the frontoparietal region when the memory was false. Both of these regions are involved in event memory, but the medial temporal lobe focuses on specific facts about the event, while the fronto-parietal network is more likely to process the global gist of the event.

Kim, H. & Cabeza, R. 2007. Trusting Our Memories: Dissociating the Neural Correlates of Confidence in Veridical versus Illusory Memories. Journal of Neuroscience, 27, 12190–12197.

http://www.physorg.com/news113671556.html

Discriminating fact from fiction in recovered memories of childhood sexual abuse

The accuracy of “recovered memories” has long been a contentious issue. A new study has attempted to settle some of the controversy by classifying people who reported being sexually abused as children according to how they remembered the event: “spontaneously recovered” (the participant had forgotten and then spontaneously recalled the abuse outside of therapy, without any prompting), “recovered in therapy” (the participant had recovered the abuse during therapy, prompted by suggestion) or “continuous” (the participant had always been able to recall the abuse). Interviewers who were blind to the type of abuse memory then attempted to confirm or refute the abuse events from outside sources. There were 71 participants who had continuous memory of the event, and 57 participants who had discontinuous memory — of these 41 recalled it spontaneously and 16 in therapy. It was found that spontaneously recovered memories were corroborated about as often (37% of the time) as continuous memories (45%), suggesting that such memories are likely to be just as accurate as memories that have persisted. However, in no case could events that had been ‘recovered’ in therapy be verified. Moreover, evidence that suggestion during therapy possibly brings about these ‘memories’ comes from the finding that individuals who recalled the memories outside therapy were markedly more surprised at the existence of their memories than were individuals who initially recalled the memories in therapy.

Geraerts, E., Schooler, J.W., Merckelbach, D., Jelicic, M., Hauer, B.J.A. & Ambadar, Z. 2007. The Reality of Recovered Memories: Corroborating Continuous and Discontinuous Memories of Childhood Sexual Abuse. Psychological Science, 18 (7), 564–568.

The study is part of an ongoing research project examining recovered memories. For more information, go to www.personeel.unimaas.nl/e.geraerts.

http://www.eurekalert.org/pub_releases/2007-06/afps-sdf061307.php

Virtual reality can improve memory, perhaps too much

A study of virtual marketing strategies has found that people who learned about a camera’s functions through an interactive virtual rendition remembered its functions better than those who learned through text and static pictures. However, they also were more likely to believe it could do things that it couldn't do.

Schlosser, A.E. 2006. Learning Through Virtual Product Experience: The Role of Imagery on True Versus False Memories. Journal of Consumer Research, 33, 377-383.

http://www.eurekalert.org/pub_releases/2006-12/uocp-vrc120506.php

Increasing consumer preferences by manipulating memory

In two experiments, people who had to solve an anagram before seeing a target brand, they were more likely to claim to have seen the brand before, and to prefer it over competing brands.

Kronlund, A. & Bernstein, D.M. 2006. Unscrambling words increases brand name recognition and preference. Applied Cognitive Psychology, 20(5), 681–687.

http://www.eurekalert.org/pub_releases/2006-06/jws-icp062606.php

Older adults more likely to "remember" misinformation

In a study involving older adults (average age 75) and younger adults (average age 19), participants studied lists of paired related words, then viewed new lists of paired words, some the same as before, some different, and some with only one of the two words the same. In those cases, the "prime" word, which was presented immediately prior to the test, was plausible but incorrect. The older adults were 10 times more likely than young adults to accept the wrong word and falsely "remember" earlier studying that word. This was true even though older adults had more time to study the list of word pairs and attained a performance level equal to that of the young adults. Additionally, when told they had the option to "pass" when unsure of an answer, older adults rarely used the option. Younger adults did, greatly reducing their false recall. The findings reflect real-world reports of a rising incidence of scams perpetrated on the elderly, which rely on the victim’s poor memory and vulnerability to the power of suggestion.

Jacoby, L.L., Bishara, A.J., Hessels, S. & Toth, J.P. 2005. Aging, Subjective Experience, and Cognitive Control: Dramatic False Remembering by Older Adults. Journal of Experimental Psychology: General, 134 (2)

http://www.eurekalert.org/pub_releases/2005-05/apa-gmc051005.php

Repeated product warnings are remembered as product recommendations

Warnings about particular products may have quite the opposite effect than intended. Because we retain a familiarity with encountered items far longer than details, the more often we are told a claim about a consumer item is false, the more likely we are to accept it as true a little further down the track. Research also reveals that older adults are more susceptible to this error. It is relevant to note that in the U.S. at least, some 80% of consumer fraud victims are over 65.

Skurnik, I., Yoon, C., Park, D.C. & Schwarz, N. 2005. How Warnings About False Claims Become Recommendations. Journal Of Consumer Research, 31

http://www.eurekalert.org/pub_releases/2005-03/uocp-nrr032905.php

How the brain creates false memories

An imaging study has shed new light on how false memories are formed. The study involved participants watching series of 50 photographic slides that told a story. A little later, the subjects were shown what they thought was the same sequence of slides but in fact containing a misleading item and differing in small ways from the original. Two days later, the subjects’ memories were tested. It was found that, during the original encoding (the 1st set of slides), activity in the hippocampus and perirhinal cortex was greater for true than for false memories, while during the misinformation phase (2nd set), the activity there was greater for false memories. In other regions, such as the prefrontal cortex, activity for false memories tended to be greater during the original event. Activity in the prefrontal cortex may be correlated to encoding the source, or context, of the memory. Thus, weak prefrontal cortex activity during the misinformation phase indicates that the details of the second experience were poorly placed in a learning context, and as a result more easily embedded in the context of the first event, creating false memories.

Okado, Y. & Stark, C.E.L. 2005. Neural activity during encoding predicts false memories created by misinformation. Learning & Memory, 12, 3-11.

http://www.eurekalert.org/pub_releases/2005-02/cshl-htb012805.php

How false memories are formed

An imaging study has attempted to pinpoint how people form a memory for something that didn't actually happen. The study measured brain activity in people who looked at pictures of objects or imagined other objects they were asked to visualize. Three brain areas (precuneus, right inferior parietal cortex and anterior cingulate) showed greater responses in the study phase to words that would later be falsely remembered as having been presented with photos, compared to words that were not later misremembered as having been presented with photos. Brain activity produced in response to viewed pictures also predicted which pictures would be subsequently remembered. Two brain regions in particular -- the left hippocampus and the left prefrontal cortex -- were activated more strongly for pictures that were later remembered than for pictures that were forgotten. The new findings directly showed that different brain areas are critical for accurate memories for visual objects than for false remembering -- for forming a memory for an imagined object that is later remembered as a perceived object.

Gonsalves, B., Reber, P.J., Gitelman, D.R., Parrish, T.B., Mesulam, M-M. & Paller, K.A. 2004. Neural Evidence That Vivid Imagining Can Lead to False Remembering. Psychological Science, 15 (10), 655-660.

http://www.eurekalert.org/pub_releases/2004-10/nu-nrp101404.php

Mood affects eyewitness accuracy and reasoning

A new study suggests people in a negative mood provide more accurate eyewitness accounts than people in a positive mood state. Moreover, people in a positive mood showed poorer judgment and critical thinking skills than those in a negative mood. The researchers suggest that a negative mood state triggers more systematic and attentive, information processing, while good moods signal a benign, non-threatening environment where we don't need to be so vigilant.

The study is to be published in the Journal of Experimental Social Psychology.

http://www.eurekalert.org/pub_releases/2004-08/uons-era082004.php

Stress reactions no guarantee of authenticity

Physical stress reactions have often been taken as evidence for the authenticity of a memory. A recent study investigated people with “memories” of alien abductions (on the grounds that these are the memories least likely to be true) and found that those who believed they had been abducted by aliens responded physically to recall of that memory in the same way as to recall of other, true, stressful events. The finding suggests that a person’s reaction to a memory is no evidence for whether or not it truly happened.

McNally, R.J., Lasko, N.B., Clancy, S.A., Macklin, M.L., Pitman, R.K. & Orr S.P. 2004. Psychophysiological Responding During Script-Driven Imagery in People Reporting Abduction by Space Aliens. Psychological Science, 15 (7), 493-497.

http://www.eurekalert.org/pub_releases/2004-06/aps-ptw062104.php

Stress no aid to memory

Numerous studies have questioned the accuracy of recall of traumatic events, but the research is often dismissed as artificial and not intense enough to simulate real-life trauma. A new study has used real stress: 509 active duty military personnel enrolled in survival school training were deprived of food and sleep 48 hours and then interrogated. A day later, only 30% of those presented with a line-up could identify the right person, only 34% identified their interrogator from a photo-spread and 49% from single photos shown sequentially (putting the interrogator in the same clothing boosted correct identification to 66%). Thirty people even got the gender wrong. Those subjected to physical threats (half the participants) performed worse.

Morgan, C.A.III, Hazlett, G., Doran, A., Garrett, S., Hoyt, G., Thomas, P., Baranoski, M. & Southwick, S.M. 2004. Accuracy of eyewitness memory for persons encountered during exposure to highly intense stress. International Journal of Law and Psychiatry, 27 (3), 265-279.

http://www.newscientist.com/news/news.jsp?id=ns99995089
http://www.eurekalert.org/pub_releases/2004-06/yu-emp060304.php
http://www.eurekalert.org/pub_releases/2004-06/ns-mfy060904.php

Memories of crime stories influenced by racial stereotypes

The influence of stereotypes on memory, a well-established phenomenon, has been demonstrated anew in a study concerning people's memory of news photographs. In the study, 163 college students (of whom 147 were White) examined one of four types of news stories, all about a hypothetical Black man. Two of the stories were not about crime, the third dealt with non-violent crime, while the fourth focused on violent crime. All four stories included an identical photograph of the same man. Afterwards, participants reconstructed the photograph by selecting from a series of facial features presented on a computer screen. It was found that selected features didn’t differ from the actual photograph in the non-crime conditions, but for the crime stories, more pronounced African-American features tended to be selected, particularly so for the story concerning violent crime. Participants appeared largely unaware of their associations of violent crime with the physical characteristics of African-Americans.

Oliver, M.B., Jackson, R.L.II., Moses, N.N. & Dangerfield, C.L. 2004. The Face of Crime: Viewers' Memory of Race-Related Facial Features of Individuals Pictured in the News. Journal of Communication, 54, 88-104.

http://www.eurekalert.org/pub_releases/2004-05/ps-rmo050504.php

Photos facilitate "recovery" of false memories

Another study demonstrating the ease with which people can be persuaded to accept a fabricated childhood memory. A Canadian study found that use of photographs (used by some psychotherapists as memory cues for the "recovery" of patients' possible childhood sexual abuse) resulted in an astounding two-out-of-three participants accepting a concocted false grade-school event as having really happened to them. The study involved 45 first year psychology students being told three stories about their grade-school experiences and asked about their memories of them. Two of the accounts were of real events advised by the participant's parents; the third was fictitious. Participants were encouraged to recall the events through a mix of guided imagery and "mental context re-instatement"--the mental equivalent of putting themselves back in their grade-school shoes. Half of the participants were also given their real grade one class photo. While a quarter or so of the participants without a photo claimed to have some memory of the false event, 67% of those shown a photo claimed some memory.

Lindsay, D.S., Hagen, L., Read, J.D., Wade, K.A. & Garry, M. 2004. True photographs and false memories. Psychological Science, 15, 149-154.
A PDF version of the article can be found at http://web.uvic.ca/psyc/lindsay/cv/index.html#publications

http://www.eurekalert.org/pub_releases/2004-03/nsae-cwb033104.php

Initial steps in a test for false memory

It appears that sensory areas of the brain might be more revealing than the areas specific involved in memory when trying to tell whether a given memory is true or false. An imaging study has found that when people correctly recognised a shape, a visual area called the ventral temporal cortex was more active than when people mistakenly identified a shape that was only similar. In similar vein, auditory regions of the brain became more active during accurate recognition of words.

http://www.newscientist.com/news/news.jsp?id=ns99994363
http://www.eurekalert.org/pub_releases/2003-11/sfn-sfb110803.php

Failing recall not an inevitable consequence of aging

New research suggests age-related cognitive decay may not be inevitable. Tests of 36 adults with an average age of 75 years found that about one out of four had managed to avoid memory decline. Those adults who still had high frontal lobe function had memory skills “every bit as sharp as a group of college students in their early 20s." (But note that most of those older adults who participated were highly educated – some were retired academics). The study also found that this frontal lobe decline so common in older adults is associated with an increased susceptibility to false memories – hence the difficulty often experienced by older people in recalling whether they took a scheduled dose of medication.

The research was presented on August 8 at the American Psychological Association meeting in Toronto.

http://www.eurekalert.org/pub_releases/2003-08/wuis-fmf080703.php

Impact of 'generative learning' on false memories

"Generative learning " refers to the idea that people 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. A recent study looked at the effect generative learning might have on the formation of false memories. Participants were given a list of words to memorize – some of the words were complete, and others were missing one letter. Complete and incomplete words came from different subject categories. After the learning period, participants were given a "distracting" math quiz, 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 used. It was found that people were far more likely to mistakenly identify a word as one they had seen before, if it was from the same category as the complete words. In another experiment, 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. 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." 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.

Soraci, S.A., Carlin, M.T., Toglia, M.P., Chechile, R.A. & Neuschatz, J.S. 2003. Generative Processing and False Memories: When There Is No Cost. Journal of Experimental Psychology: Learning, Memory, and Cognition, 29 (4), 511–523.

http://www.eurekalert.org/pub_releases/2003-07/tu-tup072403.php

Remembering imagined actions as real

The latest from Elizabeth Loftus, guru of false memory research. In this study, volunteers performed a variety actions from the commonplace (flipping a coin) to the bizarre (crushing a Hershey's kiss with a dental floss container). Later, they were asked to imagine additional actions, such as kissing a frog. At a future time, participants were asked to recall their actions on that specific day. It was found that 15% of the volunteers claimed they had actually performed some of the actions they had only imagined.

The research was reported at the "Remembering Traumatic Experiences in Childhood: Reliability and Limitations of Memory" symposium at the American Association for the Advancement of Science Annual Meeting in Denver, on February 16.

http://www.eurekalert.org/pub_releases/2003-02/uoc--fkf021303.php

Hypnosis may give false confidence in inaccurate memories

A new study suggests that hypnosis doesn't help people recall events more accurately - but it does tend to make people more confident of their inaccurate memories. Researchers asked college students, including some who were under hypnosis, to give the dates of 20 national and international news events from the past 11 years. Those who were hypnotized were no more accurate than others in choosing the correct dates. However, those who were hypnotized were more reluctant to change their answers when they were told they might be wrong. Joseph Green, co-author of the study and associate professor of psychology at Ohio State University's Lima campus, said the results of the new study don't mean that hypnosis has no value. Any kind of technique used to retrieve memories - including the use of diaries or drugs - will produce inaccurate memories. However, the difference is that people tend to have more faith in hypnosis than they do in other memory techniques.

Green, J. & Lynn, S.J. (2001). a paper presented Aug. 26 in San Francisco at the annual meeting of the American Psychological Association (hypnotism).The results of this study were presented in San Francisco at the annual meeting of the American Psychological Association on August 26.

http://www.eurekalert.org/pub_releases/2001-08/osu-hmg082201.php

New evidence shows how easily false memories can be created

About one-third of the people who were exposed to a fake print advertisement that described a visit to Disneyland and how they met and shook hands with Bugs Bunny later said they remembered or knew the event happened to them.

The study was presented the annual meeting of the American Psychological Society on June 17 in Toronto and at a satellite session of the Society for Applied Research in Memory and Cognition in Kingston, Ontario.

http://www.eurekalert.org/pub_releases/2001-06/UoW-tIta-1006101.php

Magnetic resonance imaging reveals difference between true and false memories

Tests of the human capacity for believing false memories have typically involved giving subjects a list of associated words and then testing their memory for these words by offering a new list which includes not only the previous words but also related words that were not presented earlier. A strong tendency to falsely recognize such words is characteristically found, but intriguingly, the subjects also tend to rate true items higher than false items in terms of sensory details. This suggests that, although people truly believe their false memories, part of the brain at least, recognizes that they are not as "real" as true memories. This has been something of a conundrum in false memory research.
A recent study used magnetic resonance imaging to monitor brain activity during such testing. The memory experience was made richer by having the words read on video by alternating male and female speakers. The findings were the same as in previous studies - subjects rejected new words, but falsely recognized false words related to the true words. The brain scans revealed that different parts of the brain processed true and false memories differently. The region that processes perceptual information, such as the speaker appearance and voice, was more activated for true memories.

Cabeza, R., Rao, S.M., Wagner, A.D., Mayer, A.R. & Schacter, D.L. 2001. Can medial temporal lobe regions distinguish true from false? An event-related functional MRI study of veridical and illusory recognition memory. Proc. Natl. Acad. Sci. USA, 98 (8), 4805-4810.

http://www.eurekalert.org/pub_releases/2001-05/DU-Rhun-0305101.php