For a long time, memories were thought of as the biochemical equivalent of 3 x 5 cards kept in a file cabinet. And the words on the cards were written in ink, scientists thought, because, once created and stored in the brain, a memory didn’t change. It might be vivid, but it was static, as fixed as a photograph of a remembered moment.
But in recent years, that theory has been flipped on its head. Now, leaders in memory research don’t think that’s the way the mind works at all. Instead, they’ve come to believe that memories actually are fluid things, subject to alteration every time they’re retrieved. When a long-term memory is recalled, it becomes temporarily fungible and goes through a rebuilding process known as reconsolidation. Which suggests that memories, even terrible ones, can be changed during that period when they’re once again unstable.
Several studies published last fall reinforced this notion. One, from researchers at Uppsala University in Sweden, found that a fear memory could be neutralized if the reconsolidation process is disrupted before the memory can solidify. Another, carried out by scientists at the University of St. Andrews in Scotland, concluded that even if a memory isn’t truly erased, it can be made to feel less personal or painful.