False Memories Can Form Within Seconds, Study Finds

In a new study, scientists found that it's possible for people to form false memories of an event within seconds of it occurring. This almost-immediate misremembering seems to be shaped by our expectations of what should happen, the team says. Gizmodo reports: "This study is unique in two ways, in our opinion. First, it explores memory for events that basically just happened, between 0.3 and 3 seconds ago. Intuitively, we would think that these memories are pretty reliable," lead author Marte Otten, a neuroscientist at the University of Amsterdam, told Gizmodo in an email. "As a second unique feature, we explicitly asked people whether they thought their memories are reliable -- so how confident are they about their response?" To do this, they recruited hundreds of volunteers over a series of four experiments to complete a task: They would look at certain letters and then be asked to recall one highlighted letter right after. However, the scientists used letters that were sometimes reversed in orientation, so the volunteers had to remember whether their selection was mirrored or not. They also focused on the volunteers who were highly confident about their choices during the task. Overall, the participants regularly misremembered the letters, but in a specific way. People were generally good at remembering when a typical letter was shown, with their inaccuracy rates hovering around 10%. But they were substantially worse at remembering a mirrored letter, with inaccuracy rates up to 40% in some experiments. And, interestingly enough, their memory got worse the longer they had to wait before recalling it. When they were asked to recall what they saw a half second later, for instance, they were wrong less than 20% of the time, but when they were asked three seconds later, the rate rose as high as 30%. According to Otten, the findings -- published Wednesday in PLOS One -- indicate that our memory starts being shaped almost immediately by our preconceptions. People expect to see a regular letter, and don't get easily fooled into misremembering a mirrored letter. But when the unexpected happens, we might often still default to our missed prediction. This bias doesn't seem to kick in instantaneously, though, since people's short-term memory was better when they had to be especially quick on their feet. "It is only when memory becomes less reliable through the passage of a tiny bit of time, or the addition of extra visual information, that internal expectations about the world start playing a role," Otten said.

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