Working Memory

Imagine you’re in the kitchen, following a new cookie recipe. You read: “Add 1 cup of sugar, fold in 2 eggs, followed by 2 teaspoons of vanilla.” You don’t write it down, you just hold the steps in your head as you grab the ingredients from the pantry. Like a mental sticky note, your working memory is helping you juggle bits of information while staying focused on the task.

But just as you’re cracking the eggs, your flatmate walks in and asks, “Hey, do you remember the name of that restaurant we went to last week?” You quickly answer your friend’s question and return to your cookies. Yet suddenly, you’re not sure of what you were doing. Was it 1 or 2 eggs? Did I already add the vanilla?

In that moment, you’ve hit one of working memory’s key limits. While it’s a powerful and useful cognitive skill, a brief distraction can wipe it clean. This happens because working memory holds information only temporarily and depends heavily on our attention.

Working memory is one of the brain’s executive functions. This means it’s part of a group of high-level mental skills that help us manage and regulate our thoughts and actions. Working memory is essential for day-to-day functions. When you do math in your head, try to follow a long argument someone’s making, or bake a cake and have to remember which ingredients you’ve already added, working memory plays a central role. We even use it to sign into banking apps: when you're asked to enter the 1st, 4th, and 5th digits of your PIN in a banking app, your brain pulls that info from long-term memory, holds it briefly, and picks out the right numbers. PINs are usually just 4–6 digits because anything longer would overload our limited working memory.²⁰

Unlike long-term memory—the system responsible for storing information over extended periods of time—working memory is limited in both capacity and duration. Typically, it can only store information for around 2-15 seconds unless we actively rehearse or use it.¹¹ If someone has ever recited a phone number or a short shopping list to you, it’s likely that you started repeating the information out loud or in your head in order to not forget it. 

Working memory is one of several closely related short-duration memory systems. Starting with the shortest in duration, there’s the relatively unprocessed and very short visual sensory memory (iconic memory) and auditory sensory memory (echoic memory). These typically last less than 2 seconds. Then at the other end of the scale, there’s short-term memory. While the two are often mistakenly interchanged, working memory is quite distinct from short-term memory. Both functions hold information for shorter periods of time, but working memory is different because it involves both holding information and using it.¹

Nowadays, it’s generally agreed that the basic capacity of human working memory is three to five whole items. Yet even then, this amount is reduced if we are required to attend to a large number of details (i.e., features) of these items. The more complex or detailed the information we're trying to hold in mind, the more quickly our working memory fills up—leaving less room for other thoughts or tasks.