What Is Short-Term Memory?

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What Is Short-Term Memory?

Short-term memory, also known as primary or active memory, is the capacity to store a small amount of information in the mind and keep it readily available for a short period of time.

  • Short-term memory is very brief. When short-term memories are not rehearsed or actively maintained, they last mere seconds.
  • Short-term memory is limited. It is commonly suggested that short-term memory can hold only seven items at once, plus or minus two.

Duration 

Most of the information kept in short-term memory will be stored for approximately 20 to 30 seconds, but it can be just seconds if rehearsal or active maintenance of the information is prevented. Some information can last in short-term memory for up to a minute, but most information spontaneously decays quite quickly, unless you use rehearsal strategies such as saying the information aloud or mentally repeating it.

However, the information in short-term memory is also highly susceptible to interference. Any new information that enters short-term memory will quickly displace old information. Similar items in the environment can also interfere with short-term memories.

For example, you might have a harder time remembering someone's name if you're in a crowded, noisy room, or if you were thinking of what to say to the person rather than paying attention to their name.

While many short-term memories are quickly forgotten, attending to this information allows it to continue the next stage—long-term memory.

Capacity 

The amount of information that can be stored in short-term memory can vary. In an influential paper titled "The Magical Number Seven, Plus or Minus Two," psychologist George Miller suggested that people can store between five and nine items in short-term memory.

More recent research suggests that people are capable of storing approximately four chunks or pieces of information in short-term memory.

For example, imagine that you are trying to remember a phone number. The other person rattles off the phone number, and you make a quick mental note. Moments later you realize that you have already forgotten the number. Without rehearsing or continuing to repeat the number until it is committed to memory, the information is quickly lost from short-term memory.

Short-Term vs. Working Memory

Some researchers argue that working memory and short-term memory significantly overlap, and may even be the same thing. However, the distinction that is often made is that working memory refers to the ability to use, manipulate, and apply memory for a period of time (for example, recalling a set of instructions as you complete a task), while short-term memory refers only to the temporary storage of information in memory.

The Baddeley-Hitch model of working memory suggests that there are two components of working memory: a place where you store visual and spatial information (visuospatial scratchpad), and a place where you record auditory information (phonological loop). In addition, the model points to a third part (central executive) that control and mediates these two components as well as processes information, directs attention, sets goals, and makes decisions.

How Short-Term Becomes Long-Term Memory

Memory researchers often use what is referred to as the three-store model to conceptualize human memory. This model suggests that memory consists of three basic stores, sensory, short-term, and long-term, and that each of these can be distinguished based on storage capacity and duration.

While long-term memory has a seemingly unlimited capacity that lasts years, short-term memory is relatively brief and limited. Since short-term memory is limited in both capacity and duration, the retention of memories requires transferring the information from short-term stores into long-term memory.

How exactly does this take place? There are a few different ways that short-term memories can be committed to long-term memory, however, the exact mechanisms for how this happens remain controversial and not well understood.

The classic model, known as the Atkinson-Shiffrin model or multi-modal model, suggested that all short-term memories were automatically placed in long-term memory after a certain amount of time.

More recently, researchers have proposed that some mental editing takes place and that only particular memories are selected for long-term retention. Factors such as time and interference can affect how information in encoded in memory.

The information-processing view of memory suggests that human memory works much like a computer. In this model, information first enters short-term memory (a temporary holding store for recent events) and then some of this information is transferred into long-term memory (a relatively permanent store), much like information on a computer being placed on a hard disk.

Some researchers, however, dispute the idea that there are separate stores for short-term and long-term memories at all.

Maintenance Rehearsal

Maintenance rehearsal (or rehearsal) can help move memories from short-term to long-term memory. For example, you might use this approach when studying materials for an exam. Instead of just reviewing the information once or twice, you might go over your notes repeatedly until the critical information is committed to memory.

Chunking

Chunking is one memorization technique that can facilitate the transfer of information into long-term memory. This approach involves organizing information into more easily learned groups, phrases, words, or numbers.

For example, it will take a large amount of effort to memorize the following number: 65,495,328,463. However, it will be easier to remember if it is chunked into the following: 6549 532 8463.

Mnemonics

Easily remembered mnemonic phrases, abbreviations, or rhymes can help move short-term memories into long-term storage. A few common examples include:

  • ROY G BIV: an acronym that represents the first letter of each color of the rainbow—red, orange, yellow, green, blue, indigo, violet
  • "I before E, except after C": to remember the spelling of common words
  • "Thirty Days Hath September": a rhyme used to remember how many days are in each month

Another mnemonic strategy, which dates back to around 500 BCE, is the method of loci. The method of loci involves mentally placing the items you are trying to learn or remember around a room—such as on the sofa, next to a plant, or on the window seat. To trigger your memory, you then visualize yourself going to each location, triggering your recall for that information.

Memory Consolidation

Memory consolidation is the process where our brains convert short-term memories into long-term ones. Rehearsing or recalling information over and over again creates structural changes in the brain that strengthen neural networks. The repeated firing of two neurons makes it more likely that they will repeat that firing again in the future.

Short-Term Memory Loss

For most of us, it's pretty common to occasionally experience an episode of memory loss. We may miss a monthly payment, forget the date, lose our keys, or have trouble finding the right word to use from time to time.

Still, if you feel like you're constantly forgetting things, it can be irritating, frustrating, and even cause fear that we're "losing it" or getting Alzheimer's. Short-term memory loss may even make you worried that your brain is too reliant on devices like your smart phone rather than your memory to recall information.

However, mild memory loss doesn't always indicate a problem, and certain memory changes are a normal part of aging. Short-term memory loss can also be caused by other, non-permanent factors, including:

  • Alcohol or drug misuse
  • Anxiety
  • Depression
  • Grief
  • Fatigue
  • Medication side effects
  • Sleep deprivation
  • Stress

A Word From Verywell

Short-term memory plays a vital role in shaping our ability to function in the world around us, but it is limited in terms of both capacity and duration. Disease and injury as well as increasing reliance on smartphones can also have an influence on the ability to store short-term memories as well as convert them into long-term memories.

As researchers continue to learn more about factors that influence memory, new ways of enhancing and protecting short-term memory may continue to emerge.

In the meantime, if you have had trouble remembering things lately, talk to your healthcare provider. They can give you a thorough exam to determine what might be causing your symptoms and recommend appropriate lifestyle changes, strategies, or treatments to improve your short-term memory.

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6 Sources
Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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