Why Is Memory So Good and So Bad? - Scientific American - 0 views
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Memories of visual images (e.g., dinner plates) are stored in what is called visual memory.
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Our minds use visual memory to perform even the simplest of computations; from remembering the face of someone we’ve just met, to remembering what time it was last we checked. Without visual memory, we wouldn’t be able to store—and later retrieve—anything we see.
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ust as a computer’s memory capacity constrains its abilities, visual memory capacity has been correlated with a number of higher cognitive abilities, including academic success, fluid intelligence (the ability to solve novel problems), and general comprehension.
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For many reasons, then, it would be very useful to understand how visual memory facilitates these mental operations, as well as constrains our ability to perform them
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Visual working memory is where Visual images are temporarily stored while your mind works away at other tasks—like a whiteboard on which things are briefly written and then wiped away. We rely on Visual working memory when remembering things over brief intervals, such as when copying lecture notes to a notebook.
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UC Davis psychologists Weiwei Zhang and Steven Luck have shed some light on this problem. In their experiment, participants briefly saw three colored squares flashed on a computer screen, and were asked to remember the colors of each square. Then, after 1, 4 or 10 seconds the squares re-appeared, except this time their colors were missing, so that all that was visible were black squares outlined in white.
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The participants had a simple task: to recall the color of one particular square, not knowing in advance which square they would be asked to recall. The psychologists assumed that measuring how visual working memory behaves over increasing demands (i.e., the increasing durations of 1,4 or 10 seconds) would reveal something about how the system works.
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If short-term visual memories fade away—if they are gradually wiped away from the whiteboard—then after longer intervals participants’ accuracy in remembering the colors should still be high, deviating only slightly from the square’s original color. But if these memories are wiped out all at once—if the whiteboard is left untouched until, all at once, scrubbed clean—then participants should make very precise responses (corresponding to instances when the memories are still untouched) and then, after the interval grows too long, very random guesses.
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Which is exactly what happened: Zhang & Luck found that participants were either very precise, or they completely guessed; that is, they either remembered the square’s color with great accuracy, or forgot it completely
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In a recent paper, Researchers at MIT and Harvard found that, if a memory can survive long enough to make it into what is called “visual long-term memory,” then it doesn’t have to be wiped out at all.
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Talia Konkle and colleagues showed participants a stream of three thousand images of different scenes, such as ocean waves, golf courses or amusement parks. Then, participants were shown two hundred pairs of images—an old one they had seen in the first task, and a completely new one—and asked to indicate which was the old one.
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Participants were remarkably accurate at spotting differences between the new and old images—96 percent
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In a recent review, researchers at Harvard and MIT argue that the critical factor is how meaningful the remembered images are—whether the content of the images you see connects to pre-existing knowledge about them
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This prior knowledge changes how these images are processed, allowing thousands of them to be transferred from the whiteboard of short-term memory into the bank vault of long-term memory, where they are stored with remarkable detail.
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Together, these experiments suggest why memories are not eliminated equally— indeed, some don’t seem to be eliminated at all. This might also explain why we’re so hopeless at remembering some things, and yet so awesome at remembering others.