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.