When four is not four, but rather two plus two
When it comes to working memory, the brain’s mental sketchpad, studies have largely converged on four as the magic number: It’s how many objects average adults can successfully hold in mind at once. Variations in this capacity are correlated with IQ — the more things you can think about simultaneously, the better able you are to make connections between them, and the “smarter” you’re considered.But the reasons why working memory can only juggle four items at a time have been poorly understood. Is working memory a discrete resource, meaning that once the four slots are filled, there’s simply no room for more objects? Or is it a flexible pool, divided more or less evenly among objects, and five or more cause it to be stretched too thin? Finally, where does the failure occur: in the initial perception of the objects, or later, in the remembering?Now, MIT researchers have some answers....