What Is Memory?

How memories help us

Woman's hand holding box that contains black and white photos

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Memory refers to the psychological processes of acquiring, storing, retaining, and later retrieving information. There are three major processes involved in memory: encoding, storage, and retrieval.

Human memory involves the ability to both preserve and recover information. However, this is not a flawless process. Sometimes people forget or misremember things. Other times, information is not properly encoded in memory in the first place.

Memory problems are often relatively minor annoyances, like forgetting birthdays. However, they can also be a sign of serious conditions such as Alzheimer's disease and other kinds of dementia . These conditions affect quality of life and ability to function.

This article discusses how memories are formed and why they are sometimes forgotten. It also covers the different types of memory and steps you can take to both improve and protect your memory.

How Memories Are Formed

In order to create a new memory, information must be changed into a usable form, which occurs through a process known as encoding . Once the information has been successfully encoded, it must be stored in memory for later use.

Researchers have long believed that memories form due to changes in brain neurons (nerve cells). Our understanding today is that memories are created through the connections that exist between these neurons—either by strengthening these connections or through the growth of new connections.

Changes in the connections between nerve cells (known as synapses ) are associated with the learning and retention of new information. Strengthening these connections helps commit information to memory.

This is why reviewing and rehearsing information improves the ability to remember it. Practice strengthens the connections between the synapses that store that memory.

Much of our stored memory lies outside of our awareness most of the time, except when we actually need to use it. The memory retrieval process allows us to bring stored memories into conscious awareness.

How Long Do Memories Last?

You can't discuss what memory is without also talking about how long memories last. Some memories are very brief, just seconds long, and allow people to take in sensory information about the world.

Short-term memories are a bit longer and last about 20 to 30 seconds. These memories mostly consist of the information people are currently focusing on and thinking about.

Some memories are capable of enduring much longer—lasting days, weeks, months, or even decades. Most of these long-term memories lie outside of immediate awareness but can be drawn into consciousness when needed.

Why Do We Remember Painful Memories?

Have you ever noticed that many times, painful memories tend to hang on for long periods of time? Research suggests that this is because of increased biological arousal during the negative experience, which increases the longevity of that memory.

Using Memory

To use the information that has been encoded into memory, it first has to be retrieved. There are many factors that can influence this process, including the type of information being used and the retrieval cues that are present.

Of course, this process is not always perfect. Have you ever felt like you had the answer to a question just out of your reach, for instance? This is an example of a perplexing memory retrieval issue known as lethologica or the tip-of-the-tongue phenomenon.

Organizing Memory

The ability to access and retrieve information from long-term memory allows us to actually use these memories to make decisions, interact with others, and solve problems . But in order to be retrievable, memories have to be organized in some way.

One way of thinking about memory organization is the semantic network model. This model suggests that certain triggers activate associated memories. Seeing or remembering a specific place might activate memories that have occurred in that location.

Thinking about a particular campus building, for example, might trigger memories of attending classes, studying, and socializing with peers.

Certain stimuli can also sometimes act as powerful triggers that draw memories into conscious awareness. Scent is one example. Smelling a particular smell, such as a perfume or fresh-baked cookies, can bring forth a rush of vivid memories connected to people and events from a person's past.

In order to identify a scent, a person must remember when they have smelled it before, then connect it to visual information that occurred at the same time. So, when areas of the brain connected to memory are damaged, the ability to identify smells is actually impaired.

At the same time, researchers have found that scent can help trigger autobiographical memories in people who have Alzheimer's disease. This underscores just how powerful memories can be.

Types of Memory

While several different models of memory have been proposed, the stage model of memory is often used to explain the basic structure and function of memory. Initially proposed in 1968 by Richard Atkinson and Richard Shiffrin, this theory outlines three separate stages or types of memory : sensory memory, short-term memory, and long-term memory.

Sensory Memory

Sensory memory is the earliest stage of memory. During this stage, sensory information from the environment is stored for a very brief period of time, generally for no longer than a half-second for visual information and three or four seconds for auditory information.

People only pay attention to certain aspects of this sensory memory. Attending to sensory memory allows some of this information to pass into the next stage: short-term memory.

Short-Term Memory

Short-term memory, also known as active memory, is the information we are currently aware of or thinking about. In Freudian psychology, this memory would be referred to as the conscious mind . Paying attention to sensory memories generates information in short-term memory.

While many of our short-term memories are quickly forgotten, attending to this information allows it to continue to the next stage: long-term memory. Most of the information stored in active memory will be kept for approximately 20 to 30 seconds.

This capacity can be stretched somewhat by using memory strategies such as chunking , which involves grouping related information into smaller chunks.

The term "short-term memory" is often used interchangeably with "working memory," which refers to the processes that are used to temporarily store, organize, and manipulate information.

In a famous paper published in 1956, psychologist George Miller suggested that the capacity of short-term memory for storing a list of items was somewhere between five and nine. Some memory researchers now believe that the true capacity of short-term memory is probably closer to four.

Long-Term Memory

Long-term memory refers to the continuing storage of information. In Freudian psychology , long-term memory would be called the preconscious and unconscious .

This information is largely outside of our awareness but can be called into working memory to be used when needed. Some memories are fairly easy to recall, while others are much more difficult to access.


One model suggests that there are three main types of memory: sensory memory, short-term memory, and long-term memory. Sensory memory is very brief, short-term memory is slightly longer, and long-term memory can last a lifetime.

Why We Forget

Forgetting is a surprisingly common event. Just consider how easy it is to forget someone’s name or overlook an important appointment. Why do people so often forget information they have learned in the past?

There are four basic explanations for why forgetting occurs :

  • Failure to store a memory
  • Interference
  • Motivated forgetting
  • Retrieval failure

Research has shown that one of the critical factors that influence memory failure is time. Information is often quickly forgotten, particularly if people do not actively review and rehearse the information.

Sometimes information is simply lost from memory and, in other cases, it was never stored correctly in the first place. Some memories compete with one another, making it difficult to remember certain information. In other instances, people actively try to forget things that they simply don’t want to remember.

How to Improve Memory

No matter how great your memory is, there are probably a few things you can do to make it even better. Useful strategies to deal with mild memory loss include:

  • Write it down : The act of writing with a pen and paper helps implant the memory into your brain—and can also serve as a reminder or reference later on.
  • Attach meaning to it : You can remember something more easily if you attach meaning to it. For instance, if you associate a person you just meet with someone you already know, you may be able to remember their name better.
  • Repeat it : Repetition helps the memory become encoded beyond your short-term memory.
  • Group it : Information that is categorized becomes easier to remember and recall.
  • Test yourself : While it may seem like studying and rehearsing information is the best way to ensure that you will remember it, researchers have found that being tested on information is actually one of the best ways to improve recall .
  • Take a mental picture : Systematically trying to make a mental note of things you often forget (such as where you left your car keys) can help you remember things better.
  • Get enough rest : Research has also found that sleep plays a critical role in learning and the formation of new memories.
  • Use memorization techniques : Rehearsing information, employing mnemonics, and other memorization strategies can help combat minor memory problems.


Using strategies to boost memory can be helpful for recall and retention. By learning how to use these strategies effectively, you can sidestep the faulty areas of your memory and train your brain to function in new ways.

How to Protect Your Memory

While Alzheimer's disease and other age-related memory problems affect many older adults, the loss of memory during later adulthood might not inevitable. Certain abilities do tend to decline with age, but researchers have found that individuals in their 70s often perform just as well on many cognitive tests as those in their 20s.

By the time people reach their 80s, it is common to experience some decline in cognitive function. But some types of memory even increase with age.

To help protect your brain as you age, try some of these lifestyle strategies:

  • Avoid stress : Research has found that stress can have detrimental effects on areas of the brain associated with memory, including the hippocampus.
  • Avoid drugs, alcohol, and other neurotoxins : Drug use and excessive alcohol consumption have been linked to the deterioration of synapses (the connections between neurons). Exposure to dangerous chemicals such as heavy metals and pesticides can also have detrimental effects on the brain.
  • Get enough exercise : Regular physical activity helps improve oxygenation of the brain, which is vital for synaptic formation and growth.
  • Stimulate your brain : When it comes to memory, there is a lot of truth to the old adage of "use it or lose it." Researchers have found that people who have more mentally stimulating jobs are less likely to develop dementia.
  • Maintain a sense of self-efficacy : Having a strong sense of self-efficacy has been associated with maintaining good memory abilities during old age. Self-efficacy refers to the sense of control that people have over their own lives and destiny. A strong sense of self-efficacy has also been linked to lowered stress levels.


While there is no quick fix for ensuring that your memory stays intact as you age, researchers believe that avoiding stress, leading an active lifestyle, and remaining mentally engaged are important ways to decrease your risk of memory loss.

A Word From Verywell

Human memory is a complex process that researchers are still trying to better understand. Our memories make us who we are, yet the process is not perfect. While we are capable of remembering an astonishing amount of information, we are also susceptible to memory-related mistakes and errors.

17 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.
  1. National Institute of Neurological Disorders and Stroke. Brain basics: The life and death of a neuron .

  2. Kark S, Kensinger E. Physiological arousal and visuocortical connectivity predict subsequent vividness of negative memories . Neurorep . 2019;30(12):800-804. doi:10.1097/WNR.0000000000001274

  3. Zemla JC, Austerweil JL. Estimating semantic networks of groups and individuals from fluency data . Comput Brain Behav . 2018;1(1):36-58. doi:10.1007/s42113-018-0003-7

  4. Association for Psychological Science. Fragrant flashbacks .

  5. Glachet O, El Haj M. Emotional and phenomenological properties of odor-evoked autobiographical memories in Alzheimer's disease . Brain Sci . 2019;9(6):135. doi:10.3390/brainsci9060135

  6. Camina E, Güell F. The neuroanatomical, neurophysiological and psychological basis of memory: Current models and their origins . Front Pharmacol . 2017;8:438. doi:10.3389/fphar.2017.00438

  7. Norris D. Short-term memory and long-term memory are still different . Psychol Bull . 2017;143(9):992-1009. doi:10.1037/bul0000108

  8. Cowan N. The magical number 4 in short-term memory: a reconsideration of mental storage capacity . Behav Brain Sci . 2001;24(1):87-114. doi:10.1017/s0140525x01003922

  9. Darby K, Sloutsky V. The cost of learning: Interference effects in memory development . J Exp Psychol Gen . 2015;144(2):410-431. doi:10.1037/xge0000051

  10. Mueller PA, Oppenheimer DM. The pen is mightier than the keyboard: Advantages of longhand over laptop note taking . Psychol Sci . 2014;25(6):1159-68. doi:10.1177/0956797614524581

  11. McEwen BS, Nasca C, Gray JD. Stress effects on neuronal structure: Hippocampus, amygdala, and prefrontal cortex . Neuropsychopharmacology . 2016;41(1):3-23. doi:10.1038/npp.2015.171

  12. National Institutes of Health. A well-aged mind: Maintaining your cognitive health .

  13. Goodman J, Packard MG. Memory systems and the addicted brain . Front Psychiatry . 2016;7. doi:10.3389/fpsyt.2016.00024

  14. Mandolesi L, Polverino A, Montuori S, et al. Effects of physical exercise on cognitive functioning and wellbeing: Biological and psychological benefits . Front Psychol . 2018;9:509. doi:10.3389/fpsyg.2018.00509

  15. Kivimäki M, Walker KA, Pentti J, et al. Cognitive stimulation in the workplace, plasma proteins, and risk of dementia: three analyses of population cohort studies . BMJ . 2021;n1804. doi:10.1136/bmj.n1804

  16. Beaudoin M, Desrichard O. Memory self-efficacy and memory performance in older adults: the mediating role of task persistence . Swiss J Psychol . 2017;76(1):23-33. doi:10.1024/1421-0185/a000188

  17. Schönfeld P, Brailovskaia J, Zhang XC, Margraf J. Self-efficacy as a mechanism linking daily stress to mental health in students: a three-wave cross-lagged study . Psychol Rep . 2019;122(6):2074-2095. doi:10.1177/0033294118787496

By Kendra Cherry
Kendra Cherry, MS, is the author of the "Everything Psychology Book (2nd Edition)" and has written thousands of articles on diverse psychology topics. Kendra holds a Master of Science degree in education from Boise State University with a primary research interest in educational psychology and a Bachelor of Science in psychology from Idaho State University with additional coursework in substance use and case management.