Cognitive Daily

Explaining how the brain creates false memories

Posted by Dave Munger on October 3, 2005
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It often doesn’t take much to make an eyewitness to a crime change her or his story. While Mafia hardball tactics for intimidating witnesses make the headlines, just seeing or hearing a different version of the “facts” can be enough. One key (as we’ve discussed before) is remembering the context for an event. If we can successfully recall that we personally witnessed one version of the story as it occurred last Thursday, then we’re more likely to realize that it’s different from the article we read in the newspaper the next day. If we don’t recall the context of either the original version or the revised version, our chances for making a mistake increase.

So what’s going on in our brain when we remember both the context and the event itself, and what’s different when we don’t? Yoko Okado and Craig Stark designed a study to examine the problem. They showed participants eight different slide shows telling stories on topics ranging from students talking in the hallway outside of class to the theft of a woman’s wallet. Each slide show had 50 pictures and was shown twice. During the second showing, 12 of the pictures were surreptitiously changed in an effort to create false memories. Two days later, participants were tested on their memory for those 12 critical slides.

Sure enough, a significant portion of the time, participants responded with false memories: They believed they had seen the same slide in both presentations (the man stole the wallet and hid behind a tree), when in fact they had seen two different slides (in the first slide show, the man hid behind the door, but in the second show, he hid behind the tree).

This result matched earlier research finding that when people watch a movie and then are presented with a written account that doesn’t match the movie, they will often falsely “remember” that the written story agrees with the movie. But Okado and Stark were able to take their research one step further, because their participants had agreed to perform the task while undergoing a constant fMRI, which mapped brain activity in three dimensions as they watched the slide shows.

Other fMRI research had previously revealed that when accurate memories are formed, they correspond to increased activity in particular parts of the brain: the medial temporal lobe and the prefrontal cortex. Okado and Stark’s data matched this finding: when participants had accurate memories, these parts of the brain were more active during the first slide show. When they had false memories, these parts of the brain were more active during the second, “false” slide show.

What’s more, Okado and Stark observed something else: a trend toward increased activity in other areas of the brain (parts of the hippocampus and parahippocampal cortex) when accurate memories were not being formed. Okado and Stark argue that this activity may be related to the inability to correctly recall the context for an item. Other studies have found that the left parahippocampal cortex is among the regions responsible for recalling the source of a memory. Since the region is less active when the critical second slide is presented during creation of a false memory, participants may not be forming the necessary contextual information they need to recall that the misleading slide was not, in fact, present during the original slide show. Similarly, when true memories were formed—when the misleading picture in second slide show was presented, but the participant still accurately remembered the correct first slide—these areas were again more active, suggesting that people had correctly recalled the context of the misleading second slide.

So apparently one of the key moments in determining whether a memory will be true or false occurs right as that memory is formed. During that critical instant, our entire conception of the past—right or wrong—is shaped.

So what does this say about Mafia “hardball” attempts to influence witnesses? Ironically, they may be doing exactly the wrong thing. If a witness is intimidated by physical force to change her original story, isn’t she more likely to remember the context? It might be more effective to use subtler techniques to get witnesses to change their tune.

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

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Comments

  1. #1 Mike Rundle
    October 4, 2005

    Is this similar to the deja vu effect, where a memory that should be placed in short-term is mistakenly placed in long-term memory, thus having us think we’ve seen the same situation before but a long time ago?

  2. #2 Bloggernacle Times -- This Week in Science
    October 9, 2005

    [...] So moving outside of the LDS blogs, I turn to Cognitive Daily which has a great discussion of the science of false memories. Interesting because so many consider spiritual experiences to often include false memories. (A nice catch all solution for religious skeptics) But also interesting given the debate over Hugh Nibley’s daughter last spring. It’s an interesting question, since eye witness testimonies are so untrustworthy, what is the value of religious experience. (Obviously not discussed at that blog, but surely worth of some LDS blogger’s consideration – or even in the comments here?) [...]

  3. #3 Allen
    October 25, 2005

    re: Bloggernacle comments. This research seems to me to be studying people who are making an honest attempt to relay the facts as they remember them. Having had a ‘religious experience’ myself I can say with confidence that there are some people who remember having had a ‘religious experience.’ My memories of the event are, of course, subject to the degredations of time and other influences. But these common experiences usually do not involve finding physical artifacts discussed with an angel nor the formation of a new religion. There are people who just make crap up and find, out of the millions of people in the world, enough silly people who will follow them. That may relate to your mission but it does not seem to be the topic of this fine research. I think the brain scans of habitial liars (done recently) may be more up your alley.

  4. #4 kp
    October 26, 2005

    So do scientists have false memories.. or ar they exempt from false memories, so that all their observations can be counted as facts…

  5. #5 Michelle
    October 27, 2005

    This is my first time to this website. I was wondering if anyone has heard of or even if the following senario is possible, because its happening to me and Im not sure what to do.
    When I was 17 I was at a party at a friends house and had been drinking quite heavily when I had a memory come to me so hard, so fast, it felt like I had been torn apart. I will not go into details but lets just say it was horrific, the most awful thing and NOT related to a sexual assault.
    My brain screamed that it wasnt true, I did not see this thing, no one would believe me anyway- but my psyical reaction was so stong I cant see (now anyway) how it can NOT be true. I was violently ill, shook severely and was depressed for days. Tho I had been drinking, when the memory came I felt immiediately sober. It was so bad, to this day (and I am now 34) I drink very little- usually only 1 beer on my b-day and become very ill when I do (I once thought this a psyical thing but now I think I become ill to prevent myself from becoming even slightly intoxicated).
    Okay, all these year I fought with this 1 memory. Telling my self again, its not real, it didnt happen, no way will anyone believe you. I recall telling one girl at the party when I was 17 what it was, but have told no one since. NO ONE.
    Today I am stable for the most part. However I recently was ordered to participate in a custody evaluation. The therapist spent about 4 hours with me all together and preformed a miriad of testing on all parties. All typical of a custody eval. While he said a great many good things about me, 2 things (which I had to look up on the internet) struck me hard. 1. Hyperviligance (a newer term that was hard for me to look up) which stated I was on constant alert for danger in my environment. This caused me to be very suspicious and mistrustful of other people and their motives and makes it difficult for me to form deep attachments or intimate relationships. This is all true. I dont trust others and do keep people at arms length. The second one was: Post tramatic stress disorder from unknown causes. I looked this one up and I have almost every single trait they described EXCEPT suicide or suicial thoughts/tendencies.
    Now normally, I am outgoing and happy and have a very social and socially responsible job. Ever since I read the custody eval (which is actually in my favor so its not the report upsetting me) and looked up this information (3 days ago), I have literally been in tears almost 24 hours a day. I havent been able to sleep or go to work. All I can do is think about that one memory. As soon as I think about it I become shakey, psyically ill, scared, doubled over in pain.
    I think about it constantly, wondering if I should talk to someone and how it will affect my custody case if no one believes me or if it IS false.
    So I guess I want to know if one can somehow give oneself a false memory that is so real as to cause the above described symptoms? That a basically normal person can fool themselves into a breakdown?
    Id love to know what you all think.
    Thanks

  6. #6 soulsoup -- Cognitive Daily e-learning blog, elearning blog, e-learning design, e-learning strategy,
    November 14, 2005

    [...] How ˇ°gut feelingsˇ± influence memory One theory of memory proposes that what we remember depends on our expectations. We’re less likely to remember our old classmate at the coffee shop than at the high school reunion. At the bank, we might greet the manager by name, but we only get a vague sense of recollection when we see her in the checkout line at the grocery store. So what cues that sense of expectation? If the grocery store pipes in the same music they play at the bank, will we remember her then? What if it turns out she’s not the bank manager, but another woman about the same height who happens to own the same blazer? Does the music help us notice the difference, or just make us more likely to ask a complete stranger about the status of our mortgage application? [...]