Brain has two slots for working memory
Mental version of RAM has an independent module in each hemisphere
Like side-by-side computer RAM cards, the left and the right hemispheres of the brain store information separately, a new study finds. The results help explain why people can remember only a handful of objects at one time, and suggest that people may be able to maximize their cognitive power by delivering information in equal doses to both sides of the brain, researchers suggest online the week of June 20 in the Proceedings of the National Academy of Sciences.
On average, people can hold about four things in their working memory at once, such as the location of four cards in a game of Concentration. Though many studies have linked this memory capacity to intelligence, scientists still don’t completely understand how the brain reaches this limit.
“Why can’t you think about 100 things simultaneously, or 50 things simultaneously? Why only four?” says study coauthor Earl Miller of MIT. “If we understand something about that, we’ll understand something very deep about how the brain represents information and how thoughts are made conscious.”
Miller and his colleagues tested two monkeys (monkeys also have a four-item working memory capacity) in a simple task. First, the monkeys saw two to five colored squares flash on a computer screen for a little less than a second. The screen went blank for about the same amount of time, and then the squares reappeared — but one was a different color. The monkeys were rewarded for spotting the change.