Forgetting is Key to a Healthy Mind
Solomon Shereshevsky could recite entire speeches, word for word, after hearing them once. In minutes, he memorized complex math formulas, passages in foreign languages and tables consisting of 50 numbers or nonsense syllables. The traces of these sequences were so durably etched in his brain that he could reproduce them years later, according to Russian psychologist Alexander R. Luria, who wrote about the man he called, simply, “S” in The Mind of a Mnemonist.
But the weight of all the memories, piled up and overlapping in his brain, created crippling confusion. S could not fathom the meaning of a story, because the words got in the way. “No,” [S] would say. “This is too much. Each word calls up images; they collide with one another, and the result is chaos. I can’t make anything out of this.” When S was asked to make decisions, as chair of a union group, he could not parse the situation as a whole, tripped up as he was on irrelevant details. He made a living performing feats of recollection.
Yet he desperately wanted to forget. In one futile attempt, he wrote down items he wanted purged from his mind and burned the paper. Although S’s efforts to rein in his memory were unusually vigilant, we all need—and often struggle—to forget. “Human memory is pretty good,” says cognitive neuroscientist Benjamin J. Levy of Stanford University. “The problem with our memories is not that nothing comes to mind—but that irrelevant stuff comes to mind.”
The act of forgetting crafts and hones data in the brain as if carving a statue from a block of marble. It enables us to make sense of the world by clearing a path to the thoughts that are truly valuable. It also aids emotional recovery. “You want to forget embarrassing things,” says cognitive neuroscientist Zara Bergström of the University of Cambridge. “Or if you argue with your partner, you want to move on.” [For more on emotional memory, see “A Feeling for the Past,” by Ingfei Chen.] In recent years researchers have amassed evidence for our ability to willfully forget. They have sketched out a neural circuit underlying this skill analogous to the one that inhibits impulsive actions.