Why Is Memory So Good and So Bad?
What did you eat for dinner one week ago today? Chances are, you can’t quite recall. But for at least a short while after your meal, you knew exactly what you ate, and could easily remember what was on your plate in great detail. What happened to your memory between then and now? Did it slowly fade away? Or did it vanish, all at once?
Memories of visual images (e.g., dinner plates) are stored in what is called visual memory. 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. Just 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.
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. Yet although these big questions have long been debated, we are only now beginning to answer them.
Memories like what you had for dinner are stored in visual short-term memory—particularly, in a kind of short-term memory often called “visual working memory.” 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.