by Emma Kandel
Picture this: You walk into the grocery store, confident that you’ll remember everything on your list, but walk out with everything except the one thing you actually needed. You just reviewed that grocery list in the car 10 minutes ago! So what happened here? Why do we often forget the things that we just rehearsed in our heads? In this article we will examine the limited capacity of working memory and the various factors that influence said capacity.
Working Memory Capacity is Limited!
Working memory is the limited capacity cognitive system that allows us to temporarily hold and manipulate information in mind (Baddeley, 1992). Working memory plays a very important role in how we interact with our environment and encode our surroundings (Adam et al., 2025). In other words, working memory is the “stuff” you are holding in mind right now, whereas long term memory refers to the “stuff” that our brains store in the long term.
From remembering a phone number, to navigating a crowded grocery store while thinking of a shopping list, to memorizing all of the organelles in the cell minutes before your biology exam, the ability to hold and manipulate information in mind is critically important to our daily lives. The catch is that working memory has capacity limits, whereas long term memory is less so “limited”. Early research suggested that we can juggle about 7 items at once in our working memory (Miller, 1956), but other studies suggest the number might actually be closer to 3 or 4 (Cowan, 2010). That means when your grocery list creeps up past a handful of items (apples, bread, cereal, pasta, yogurt, and milk), you’re already stretching that system pretty thin!
It is known that the capacity of working memory varies based on a number of factors, including how complex the information is (Luck & Vogel, 1997), the load/amount of information we are trying to remember (Lin et al. 2021), and how helpful the information is to achieving a goal (Oberauer et al., 2016). The variation in these “magic numbers” stems from the fact that working memory is a flexible and adaptive system that varies based on all of these factors (Luck & Vogel, 1997; Oberauer et al., 2016). However, the exact number of items that can be held in mind at one time is not what psychology researchers are often most concerned with. Rather they tend to study the strategies and conditions that can help mitigate these limits.
Factors that influence working memory capacity
So, how do we keep track of more than just a few items at a time? The good news is that our brains are relatively adaptable, and we can work around these limits. One trick our brains use is chunking, or grouping items into categories (Gobet, F, et al. 2001). Instead of holding six separate grocery items in mind, you might group them into categories: produce (apples), carbs (bread, cereal, pasta), and dairy (yogurt, milk). Suddenly, six items shrink into three manageable chunks. This same principle explains why phone numbers are broken up into chunks instead of being written as a long string of numbers!
Another important factor is that we are more likely to encode items that connect to a common goal, and research shows that relevance to a goal encourages filtering during memory encoding (Brady & Störmer, 2022). Our working memory is frequently utilized as a means to achieve a goal, such as grocery shopping, and we are able to prioritize information based on our current goal-state in our working memory (Grogan et al., 2024). For example, if your goal is to have a bowl of cereal for breakfast tomorrow, and you’re already thinking about that meal while shopping, this focus can make it much easier to remember the milk (because nobody likes dry cereal). Goal setting, then, becomes a powerful strategy for remembering longer lists. So next time you write your grocery list, try planning a few recipes or meals for the week. Your brain will have a clearer purpose to anchor those items, and they’ll be less likely to slip your mind!
Working memory is shaped by likely hundreds, if not thousands, of elements that can influence what we’re able to hold in mind at any given time. Researchers are continuing to uncover new ones every day, ranging from emotional state, to motivation, to sense of agency, to even the physical environment we’re in! So, the next time you forget the milk, don’t beat yourself up. Remember that our memory system wasn’t built for flawless recall of long lists, and you can’t be blamed for forgetting the milk when there is such a tempting snack aisle to peruse! Our working memory system exists to help us navigate the present moment, and sometimes, that means leaving the milk behind.
References
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