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Memory reconstruction, source monitoring, and emotional memories

Video transcript
One interesting thing we know about how our brain retrieves information is that, unfortunately, it doesn't work like a computer pulling up a file. When you save a document on your computer, it will look exactly the same next time you open it. Whether you open it today, tomorrow, or next year, that document will be exactly the same as the moment that you saved it. Our brain, however, doesn't work that way. Every time we retrieve a memory, we modify it slightly. This is why memory is sometimes described as being reconstructive. Whenever we think we're remembering something picture perfect, we are actually changing that memory in small ways, according to our mood, goals, or environment. You might think of someone telling a story about a fish they caught. The first time they tell the story, it's a small fish. But every time they retell the story the fish gets bigger. Sometimes these alterations are due to our own desires or moods. If there's a gap in our memory, then our brain might fill it in with something logical or desirable. Another factor that can affect our ability to retrieve accurate information is receiving false or misleading information after we encode something but before we try to retrieve it ourselves. For example, one study had people watch a video in which a car stopped at a yield sign. After the video, participants received a written description of it. And some of those descriptions had false information. They said that the car stopped at a stop sign instead of a yield sign. People who got this description were more likely to report they'd actually seen a stop sign in the video than people who didn't get this description. Similarly, another study showed the example of misleading information, so not necessarily false information but just misleading. People watched a traffic safety video in which they observed a car crash. Immediately after the video, people were asked questions about what happened. And the key question was, how fast were the cars going when they hit each other? Except some people got the question with the verb hit, like I just read. And some people got the question with the verb smashed instead of hit. A tiny difference, right? But a couple weeks later those same participants were asked if there was any glass on the ground after the traffic accident in the video they had watched. Now, there wasn't any glass on the ground in the video. But if people had received the question with the more violent verb, smashed, then they were much more likely to say, yes, there was glass on the ground than if they had received the question with the more neutral verb, hit. That tiny misleading word affected their entire memory for the event. And this is one reason that investigators have to be so careful when questioning witnesses. Even a seemingly insignificant phrase can impact what people think they recall. One reason false or misleading information can have such a strong impact on memory is that people often have difficulty with something called source monitoring, that's keeping track of where various information came from, the source of the information. So even if they had some confusion over whether they'd seen a yield sign or a stop sign, they might have difficulty remembering if the yield sign was in the original video or the written description. Similarly, people who got the question with smashed instead of hit might have difficulty separating out memories of the video car crash from other car crashes on movies or something where there was glass on the ground afterwards. So you might wonder if some types of memory could be immune to this sneaky effect of misinformation. After all, some memories probably seem really vivid to you. And it's hard to think that they might not be true. And sometimes people think that if a memory is particularly emotional, then it's less susceptible to forgetting and more likely to be accurate. Emotional memories can be positively or negatively valenced. The birth of your child might be very positive. It's a positive emotion, so it's a positive valence. But a memory about the planes hitting the twin towers on September 11, 2001 might be very negatively valenced. Whether positive or negative, highly emotional memories that feel extremely vivid are called flashbulb memories. And even though these memories can seem as real as life, they're just as susceptible to reconstruction as less emotional memories. Now, I don't want you to walk away thinking that everything you remember is a lie. Often these minor reconstructions aren't very drastic. But what you should understand is that memory is not a video recorder. It's the very organic result of neural connections in your brain which can be altered and reformed each time they're exercised.