Everything you need to know about short-term memory

Do you know that there are several types of memory? Today, we will have a look at short-term memory. We will focus on how it works and on the link between short-term memory and long-term memory. Short-term memory is the memory we all use to recall information in a short time. It is, by nature, limited. For example, the average length of time information is retained in short-term memory is 30 seconds. The number of elements that we can "store" simultaneously is also limited: it is seven elements +/- 2. This is called the memory span. Here’s everything you need to know about short term memory. 

What is Short term memory?

Short term memory is also called immediate memory; it operates for a maximum of 30 seconds. It kicks in when a stimulus presents itself, just before it is stored in long-term memory. It is difficult to distinguish where working memory ends, and short-term memory begins. The latter includes verbal and visual memories. Used to manage daily activities, it is a good indicator of alertness and learning abilities. Short-term memories are stored briefly in the parietal lobes, and the neurotransmitter involved being acetylcholine. 

Mechanism of short-term memory 

According to the model of Atkinson-Shiffrin (1968), it is made up of several elements:

Its first component is sensory memory. When we talk about the short-term memory, its detention period varies between one hundred milliseconds and 2 seconds. Nevertheless, it allows us to keep faithfully information gathered by one of our senses (smell, hearing, sight, touch). Sensory memory is very busy, but it is difficult to access its information, particularly because of the very short retention period.

If the information is selected, it goes into short-term memory. The information retention time is 30 seconds. If used, it can be repeated to keep it in memory longer. 

Finally, when information is useful and repeated, it can be transferred to long-term memory. The information is then kept for a very long time. 

How does short-term memory work anyway? 

What information ends up in short-term memory depends on the content. If information is important to you because it interests you, affects you personally, or is emotionally charged, it moves on to your short-term memory. Only when you have learned something seven times does the information arrive in long-term memory. It's quite normal that we don't remember every detail. Short-term memory erases 90% of the information stored. After all, it is not necessary to know years later that you had a pizza with pizza hut on April 2nd, 2018 at 12 noon. On average, the brain deleted irrelevant data after just 18 seconds. Several brain areas interact with each other so that you can remember details. You can actively train this interaction and thus improve a poor short-term memory.  

The role of short term memory 

Our short-term memory is one of the four major areas of the brain. In fact, it consists not of just one memory, but of a whole group of memories that are all strongly interlinked. And it has to be because, without the many cognitive skills that our short-term memory gives us, we would not be able to survive. 

Functions of short term memory

Our short-term memory has many functions. In the last few decades, it has been established that our short-term memory not only stores and retrieves some information, but is actually one of the most important areas in our brain. 

Nowadays, short-term memory is mainly called working memory, and it is responsible for the reception and processing of all information and stimuli that we are exposed to. That means all skills like:

- Arithmetic

- Read

- Think

- Notice

- Recall

- logic

- creativity

- attention

- concentration

And much more are all taken over by our short-term memory. Unfortunately, despite its many tasks, our short-term memory only has a relatively small capacity. This is because, in the past, our brain only had to focus on relatively few things at the same time.  

Differences between short term memory and long term memory 

Short-term memory differs from long-term memory in several ways. The first concerns its ability to memorize information. In fact, it is limited in retention time and in its capacity for memorization, unlike long term memory, which is described as almost unlimited memory. And the difference does not end there. 

The recency effect and the primacy effect: 

The recency effect refers to the ease of recalling the last items in a list of stimuli. At the same time, the primacy effect expresses the ease of recalling the first elements of a list of stimuli.

To show these effects, scientists have developed an experiment. It consists of teaching a list of words to a subject and asking him to recall this list. Scientists have been able to demonstrate the existence of the effect of recency and primacy when the subject is asked to repeat the words directly after the memorization work. Conversely, the recency effect disappears if the subject waits 30 seconds before returning the list of words.

The researchers concluded that the recency effect was linked to short-term memory. In addition, the primacy effect is intact because the information is already encoded in short-term and then long-term memory. This shows that the primacy effect is related to long term memory. 

What to remember from short term memory:

- Short-term memory has a limited capacity. Its memory span is 7 +/- 2 elements. Its duration is approximately 30 seconds.

- The information stored spend of a sensory memory to the short term memory, and possibly long-term memory

- It is therefore interesting to learn to focus your attention on a limited number of elements at a time to improve the efficiency of memorization. This is why mnemonics are effective, as are advanced memorization tools such as the Mental Palace. 

Short term memory problems

Short-term memory ensures attention and concentration in everyday life. Sometimes the short-term memory does not filter properly so that important learning material is also classified as "unimportant" and does not make its way into long-term memory.

However, if you keep getting things wrong and can no longer remember where they are, and if you regularly forget topics or names, your short-term memory is likely to deteriorate. People who are forgetful or bumbling worry that they may have a bad memory - especially the fear of dementia and Alzheimer's disease increases with age. However, it is normal for short-term memory to deteriorate with age. 

Loss of short term memory

Some people fear short-term memory loss. Those affected cannot then take in and evaluate new memories. This means an enormous restriction in everyday life, under which communication with fellow human beings and orientation suffers. Short-term memory loss can be caused by brain disease, dementia, infection, or a stroke. 

Train your short-term memory 

It is normal for memory to weaken with age. You can improve your short-term memory with specific exercises. Memory training creates new neural networks in the brain. This improves not only short-term memory but also all other cognitive skills such as:

- Logical thinking

- Understanding of language

- concentration

- attention

Since nowadays everything can be looked up and checked due to smartphones immediately, this impairs the ability to memorize things. But what can you do yourself? With small brain jogging units, you challenge your short-term memory and keep yourself mentally fit. Possibilities are:

- Memorize phone numbers

- Go shopping without a memo

- Spelling difficult words correctly

- Learn the multiplication tables by heart

You can also use special memory exercise programs or solve brain teasers. A healthy lifestyle with good nutrition and regular exercise can also have positive effects on brain performance.  

Sperling et al. wanted to prove the existence of sensory memory. For that, they developed an experiment which consists of placing an individual in front of a matrix of 3 X 3 letters. The image is broadcast for 1/20 of a second. The goal is for the individual to find the nine letters. Subject results were approximately 4 to 5 letters found.

Several causes are possible at this stage. Indeed, it is possible that the subjects did not have time to see all the letters, and it is as much possible that they did not manage to memorize everything. 

The experience becomes more interesting when the researchers decided to add an element. Right after the image disappears, the researchers play sound called stimuli that can have multiple tones. Each tone represents a row of the matrix. The high tone designates the top line, the middle tone, the middle line etc. The objective of the individual is to transcribe the line expressed by the sound. The results of this new experiment show that the subjects systematically give the correct answer.

This effectively proves that there is indeed a sensory memory because once the matrix is ​​encoded; it remains in visual space for a few seconds. It is the stimuli that will indicate where the subject's attention should be. The conclusion of this study shows that when we have a visual stimulus, it persists a few seconds after its disappearance.

Author: Vicki Lezama