Calculating our brain’s capacity for concurrent thoughts
On the average afternoon, I’m often trying to keep track of my work obligations, household maintenance, what my three-year-old is about to break, what my wife’s schedule for the day is, when my first-grader needs to be picked up, and ooh, did my phone just buzz?! None of these things are really that complicated on their own, but as a group they’re likely to be more than my brain can keep track off, at which point items start being purged from my working memory. Scientists used to believe that a normal number of concepts to juggle was seven, but newer research has pushed that number down to four. It doesn’t feel like much, but it can be optimized, if you get a handle on what ideas are worth working with.
It’s important to realize what counts as a mental memory unit in all this. The complexity of an idea or experience isn’t necessarily what counts, unless that complexity forces you to think about it as more than one idea. For example, a sentence like “I forgot where I put the ice cream.” can occupy one memory unit, or if you think about each word as a discreet thing, eight at once. More details don’t have to make things harder to keep track of, as long as they’re related enough to be thought of together.
When the medium matters
The type of information you’re handling can make a difference too. Remembering a sequence of seven items is easier if you hear it thanks to how our brains handle audio versus visual information. This was determined after people using sign language were found to have lower ceiling on sequence memorization, but were on par with hearing people for memorizing visuals in general. On the flip side, information received through sight or touch seems to endure longer than things we only hear. This bias may be built into our brains, as it has also been found in other primates like chimpanzees and various monkeys.
Managing our available memory
So aside from being aware of these limits, is there much we can do to boost how well we handle different threads of information? You aren’t likely to suddenly expand your brain’s mental workspace, but you can try to choose what goes in it more carefully. People who seem to juggle more units of information better are likely just better at ignoring things that they don’t need at that moment so that the data they do want remains at their mental fingertips. If you think of your working memory as a desk, clearing the desk of clutter will probably help you get your work done better than simply making a larger space to pile on distractions.
Of course, being able to selectively ignore things may be easier said than done. As I write this, two children are literally running in circles while shrieking and yelling, just a foot away from my desk. I ever want to keep the mental framework of this post intact, I probably need to start ignoring… something…
Source: Ignoring Stuff Is Good for Your Memory by Julia Shaw, Scientific American