Short-term memory (STM) is a type of memory that can hold a small amount of information for a limited period of time. The duration and capacity of short-term memory is quite limited, holding between five to nine pieces of information for around 20 to 30 seconds.
You’ve probably experienced these limitations yourself many times. Consider the last time you thought of something you needed to do and walked into another room to do the thing you just thought of, only to discover that you can’t remember what you would do. This is an example of short-term memory failure.
Problems with short-term memory can range from minor annoyances to more severe signs of a serious health problem. Understanding how short-term memory works can help you better spot potential issues and look for ways to boost your short-term memory.
Characteristics of Short-Term Memory
Short-term memory is distinguished from other types/stages of memory by a few key factors:
- Limited capacity: Short-term memory can only hold a limited amount of information. In his classic research, George Miller suggested that this number was the “magic number seven, plus or minus two. This means STM can hold between 5 and 9 items at a time.
- Limited duration: As the name indicates, short-term memory is brief. While estimates vary, it typically lasts around 15 to 30 seconds unless the information is actively rehearsed.
Understanding How Memory Works
A number of models have been introduced to explain how memory works and the different parts of memory. Some theories describe memory as consisting of distinct types of memory. Others conceptualize these as stages of memory.
In any case, the four main types (or stages) of memory are:
- Sensory memory: This is the initial stage of memory that holds sensory information for a very brief period of time. While it has a large capacity, it is very brief in duration.
- Short-term memory: Information that you attend to can be transferred from sensory memory to the second stage of memory, which is short-term memory.
- Working memory: This type of memory is sometimes described as a distinct type of memory, it is often identified as a form of short-term memory. It is the part of memory for the immediate, small amount of information you are currently using.
- Long-term memory: Short-term memories that are rehearsed may be transferred to long-term memory, an enduring and virtually limitless store that can last a very long time. Long-term memories can also be identified as either explicit (which form consciously) or implicit (which form unconsciously).
How Short-Term Memory Differs From Working Memory
While short-term and working memory are often described as the same, not all experts agree. Some feel that they are essentially the same thing.
Some important differences that help distinguish between the two:
- Working memory is active: It involves actively using and manipulating small amounts of information.
- Short-term memory is passive: It involves a temporary store for information you have attended to.
Short-term memory is where these memories are briefly stored, while working memory allows them to be actively utilized and manipulated.
Consolidating Short-Term to Long-Term Memory
Because short-term memory is so limited, information has to be transferred into long-term memory in order for it to be retained. So, how exactly does this information go from being the type of information we forget after about 30 seconds to the type of information we remember for years or decades?
Short-term memories become long-term through a process known as memory consolidation. This process involves a few different factors:
Repetition
Every time you access a memory, the neural network involved in that memory becomes stronger. It’s a bit like walking along a hiking trail; the more frequently you walk it, the more worn it becomes.
As you actively rehearse information in short-term memory, those neural networks fire together and strengthen the “path” for that memory. This means that the next time you want to access that specific information, it will come to mind much more readily.
Elaborative Rehearsal
Repetition is important, but forming meaningful connections with existing information can further cement memories into long-term storage.
Elaborative rehearsal involves thinking about the meaning of new information and memories you have acquired and then making connections or associations with things you have already stored in your memory.
Sleep
Sleep also plays a crucial role in memory consolidation. Important structures in the brain, specifically the hippocampus and neocortex, are key to this process. During sleep, the hippocampus consolidates short-term memories and moves them into the brain’s cerebral cortex.
When people experience damage to the hippocampus, they may experience retrograde amnesia, which involves the inability to remember past events stored in long-term memory.
Strategies for Improving Short-Term Memory
If you find yourself constantly forgetting things like where you put your phone, a name you just learned, or other types of information that you need to live your day-to-day life, it might mean your short-term memory could use some work. There are a number of strategies you might try to help boost your short-term memory:
Chunking
Chunking involves grouping information into smaller and easier to remember, chunks. If you were trying to memorize a list, for example, you might group the items into smaller units based on similar features.
If you want to improve your short-term memory, chunking can be a useful tactic.
Mnemonics
Mnemonics are memory strategies that involve using easily remembered elements, like acronyms or rhymes, to remember information. Using mnemonics can boost short-term memory by creating associations between things you’ve just learned and other things you already know that are easy to recall.
Visualization
Visualization involves creating mental images of the information you are trying to remember. This can help keep the information in your short-term memory more readily, and may facilitate the transfer of this information from short-term memory into long-term memory.
Real-World Examples of Short-Term Memory
Short-term memory plays a pivotal role in our lives. Our short-term memory is constantly in use as we live our lives, allowing us to remember what we are doing, what we’ve just said, the things we’ve just heard, and where we place things just moments ago.
Academic Performance
In school, short-term memory is vital to the learning process. It allows us to take in what a teacher says and temporarily hold essential details. It also allows us to remember things we’ve just read, relate what we learn to prior knowledge, and respond to questions the teacher asks.
Learning strategies like taking notes, using visual aids, and chunking related information on flashcards can help facilitate the transfer of short-term memories into long-term storage.
Everyday Life
Short-term memory allows us to function in our daily life, including at home, at work, and in our relationships. When someone tells us about an appointment, name, or phone number, we store that information in short-term memory until we can jot it down for future use.
Short-term memory also allows us to remember what we look for on the self as we shop for groceries. Plus, it lets us hold information long enough for us to respond to what others have to say.
Short-Term Memory Loss
Short-term memory loss can have a serious impact on a person’s ability to function. Some of the different factors that can contribute to short-term memory loss include:
Anxiety and Stress
Stress hormones can affect the brain’s hippocampus, a region that plays an important role in memory formation. Anxiety can also interfere with your ability to concentrate, which can affect short-term memory.
Sleep Deprivation
Poor quality or inadequate sleep can affect various cognitive functions, including short-term memory. Remember, sleep plays a vital role in memory consolidation. That’s why you might find it more difficult to remember things when you are tired or sleep-deprived.
Head Injuries
Traumatic brain injuries can also affect short-term memory. The degree of impairment that a person experiences depends on the nature, location, and severity of the damage.
Medical Conditions
Neurodegenerative disorders such as Alzheimer’s disease and dementia also affect short-term memory. This loss is progressive, which means that it worsens over time.
Certain Medications
Some medications can have an impact on short-term memory. This includes antihistamines, some antidepressants, and benzodiazepines.
Depression
People often experience a variety of cognitive symptoms when they are depressed, including difficulties with concentration and memory.
Aging
The normal aging process can also lead to changes in short-term memory. Such changes are normal and often mild. If a person experiences more severe impairments as they age, it might be a sign of a more serious problem.
Substance Use
Using alcohol and other types of drugs can also have an effect on memory. Some of these impairments may be more severe when a person is intoxicated, but long-term use can affect the brain’s ability to process information and form memories effectively.
If you have noticed problems with your short-term memory, you might try strategies such as chunking or visualization to improve it. But if these impairments seem serious, are worsening, or are affecting your ability to function, it is important to talk to your doctor to learn more.
Sources:
Chai WJ, Abd Hamid AI, Abdullah JM. Working memory from the psychological and neurosciences perspectives: A review. Front Psychol. 2018;9:401. doi:10.3389/fpsyg.2018.00401
Cowan N. What are the differences between long-term, short-term, and working memory? Prog Brain Res. 2008;169:323-338. doi:10.1016/S0079-6123(07)00020-9
Mayo Clinic. Memory loss: When to seek help.
Squire LR, Genzel L, Wixted JT, Morris RG. Memory consolidation. Cold Spring Harb Perspect Biol. 2015;7(8):a021766. doi:10.1101/cshperspect.a021766
Vallar G. Short-term memory. In: Reference Module in Neuroscience and Biobehavioral Psychology. Elsevier; 2017:B9780128093245032000. doi:10.1016/B978-0-12-809324-5.03170-9
Zlotnik G, Vansintjan A. Memory: An extended definition. Front Psychol. 2019;10:2523. doi:10.3389/fpsyg.2019.02523