If I say a random string of numbers out loud, say 1593657292759381380473, how many of these numbers do you think you will be able to immediately remember?

The magical number

Some scientists say that you should be able to remember about seven of them. More precisely, since a paper from the 1950s, called ‘The magical number seven, plus or minus two’, some have suggested that the capacity of our working memory is typically somewhere between five and nine things, although some scientists argue that this capacity is actually closer to four.

By things I mean units or chunks of information. For our number, you could for example remember it as one, five, nine, three. In this case, each individual number counts as a unit. However, you will be able to remember more of the number if you parse it differently; fifteen, ninety-three, sixty-five, seventy-two. Both of these count as four units, the information is just combined differently.

So, when scientists say that you can keep a certain number of things in working memory, these individual things can be of varying size, complexity, and importance. Either way, working memory is small but really important.

Working memory

What is working memory? Working memory is your brain’s dashboard. It’s the place you can temporarily put information while your brain decides whether or not it is worth the effort to put it somewhere more permanent, like your long-term memory.

As it turns out, different senses have different dashboard capacity. This means that how much you can remember seems to depend on whether, for example, someone says something to you or shows something to you. Because of this, it is important to look at different types of working memory separately.

To make matters even more complicated, each and every person has a different ability to keep things in working memory. These individual differences in working memory capacity are important because they have been shown to strongly predict things like intelligence; more working memory capacity generally equals more intelligence.

But, why are some people able to keep more in their working memory than others?

Ignoring stuff

Lucky for us, new research by a team of scientists at Simon Fraser University has shed light on why some people may be able to keep more things on their brain dashboards than others.

The research team, led by psychology professor John McDonald and doctoral student John Gaspar, learned about differences in visual memory by recording people’s brain waves and tracking how they paid attention.

At this point you might be asking, why are we talking about attention? Well, attention and memory are inextricably linked. By paying attention to an object, you increase its representation in the brain and make it easier to remember.

But making something easier to remember is only one aspect of attention. Paying attention also means ignoring all of the distracting information in our world. And this is where people differ significantly.

In their study, people who had low working memory capacities were unable to suppress important, distracting information. According to John Gaspar; “This indicates that it might not be about how much relevant information you can remember but instead it might be about how good are you at ignoring irrelevant information.”

This fit well with the scientists’ previous research, which had already demonstrated that the human brain has distinct processes for locking attention onto relevant information and for suppressing irrelevant information.

So, there we have it; it’s not just about how much information we can cram into our memories at once, it also about how much we can keep out.

Next time you find yourself having a hard time remembering a phone number or image, just blame your distracted brain.