Short-term memory: knowing how it works to enhance it (Part 1)

We have all heard about long-term and short-term memory, and we have all got a little bit confused about what kind of processes they require in order to function.

This is the first of a two parts article that will try to describe how memory works and which enhancement strategies can be implemented to take the most of it, starting with a focus on short-term memory.


If you try looking for a specific area in the brain where memory is placed, you will be disappointed: both long-term and short-term memory, in fact, are theoretical constructs related to how and how long information is stored.

In particular, short-term memory could be defined as the mechanism that allows retaining over a short period of time a certain amount of information. How many items can it store?

Let’s try with a simple sequence of numbers, read it and try to remember as much of it as you can: 1-0-3-4-6-1-9-7-3-5-2-9.

If you now close your eyes and think about the sequence, you will see you are able to recall five to nine items: this is because short-term memory can store around seven elements (or “slot” of contents) at the time. This capacity can vary depending on a number of internal and external factors: personal differences, function of the material, length of the words, emotional relevance of the stimuli can all affect a person’s ability to remember.

Try to repeat the sequence now: can you recall it? Probably not, because retention time for short-term memory is about thirty seconds, depending on the same factors as capacity.

If you try to read this sequence of letters instead – A P A R T M E N T – you will be able to recall the single items, but you will probably recognize the word “apartment” too. This is due to the so-called “working memory”, the type of memory that allows to carry out complex cognitive tasks – like language comprehension, reading, learning, or reasoning – on temporary-stored information.

What can you tell about the number sequence you read 2 minutes ago? It has completely disappeared from your memory, hasn’t it? Thanks to organizing and manipulating information store in the short-term memory, in fact, the brain can determine whether it could be relevant or not, and therefore let it fade away – as the number sequence, totally unuseful – or move it to long-term memory.



When given a sequence of numbers, everyone would like to be able to remember the most of it. Let’s try with the initial sequence again: 1-0-3-4-6-1-9-7-3-5-2-9. One of most effective way to improve the ability to retain data in the short term is chunking, namely grouping related information together. What does it mean in practice? It means it would be easier to remember these twelve items if they were in fact six: if you read it as 10-34-61-97-35-29, you will be probably able to recall at least five double digit number. Isn’t this the way we usually repeat phone numbers? The reason why this works is that it has been proven that placing more information in each memory “slot” allow to expand short-term memory’s capacity, while preventing cognitive overwhelm.



Now let’s think about the way you read the sequence: did you read it or repeat it out loud? Even if you didn’t, your short-term memory transformed visual data into sounds: that is because it leans on auditory stimuli to memorize information more efficiently, thanks to a the process called “rehearsal” described by Atkinson and Shiffrin. It claims that when concepts are reinforced with audio support, it becomes possible to acoustically encode information, thereby committing it to long-term memory.



In order to establish a piece of information in the memory, a good strategy is the reapplication of previously learned concepts to scenarios, simulations or even end-of-chapter assessments. Can you recall your Math teachers making you do tons of exercises using the same formula? You probably hate those homework, but then were able to remember the formula much longer. This is because connecting information to real world challenges reduces knowledge decay, by making it more relevant and perceived as useful.



All these enhancement strategies should take into account in which point of the lesson the information is placed. Can you tell if there is a structure in the brain related to memory? And what did we say about your Math teacher?

After having read this article so far, these are probably the two pieces of information you can recall most easily, and that’s no surprise. It is known, in fact, that we remember items according to the so-called “serial position curve” and the primacy and regency concepts: items at the beginning are easier to remember because the short-term memory has more time to absorb it, items at the end because no others are learned afterward. This is why you can find a short summary of contents at the beginning and the end of the learning unit, and also why most relevant ideas or key takeaways are usually placed at the ends of the lesson.

Now you know all about short-term memory. But what about long-term memory instead?

You can find more in the next article!


Atkinson, R. C., & Shiffrin, R. M. (1971). The control of short-term memory.


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