A psychology instructor asks for one precise definition of memory. Which answer matches the way the APA Dictionary of Psychology and OpenStax Psychology 2e describe it?
Choose an answer, then check it.
Psychology · Foundations
Memory
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In 30 seconds
memory The ability to store and retrieve information over time; psychologists treat it as a set of processes rather than a single thing. Full entry → is the ability to store and retrieve information over time. Psychologists describe it as three stages — encoding The first stage of memory: converting experience into a form the memory system can hold. Full entry →, storage The second stage of memory: keeping encoded information over time. Full entry →, and retrieval The final stage of memory: getting stored information back into awareness when it is needed. Full entry → — and as three boxes: sensory memory A very brief, relatively unprocessed holding of sensory input, lasting up to a couple of seconds. Full entry →, short-term (working) memory, and long-term memory The relatively permanent store of skills and knowledge that can be drawn on hours, weeks, or years later. Full entry →. Long-term memory comes in two kinds: explicit, the facts and events you can consciously recall, and implicit, the skills that show up in what you do. And memory is not a recording: every time you remember, you rebuild the past.
Why this matters
Your sense of who you are is built from what you remember. The story of your life — where you grew up, who your friends are, what you have learned to do — is stored and retrieved information; without memory, a conversation about yesterday would be impossible. Academically, memory is the foundation of all learning: every course you take assumes you can hold onto what you studied. Practically, memory is at work whenever you recognize a face, follow a recipe, or keep a promise. And honestly, understanding that memory rebuilds rather than replays changes how you treat your own recollections — and other people's.
The college version
What memory is
Memory is the ability to store and retrieve information over time. That working definition comes from two authoritative sources. The APA Dictionary of Psychology defines memory as the ability to retain information or a representation of past experience across some interval of time, based on encoding, retention, and retrieval. OpenStax Psychology 2e describes it as the set of processes used to encode, store, and retrieve information over different periods of time. Both sources agree: memory is not one thing but a set of processes that carry information in, hold it, and bring it back. The Noba Project's memory module describes it as everyday terms: memory is in some ways like file drawers where you store mental information, and also a series of processes that decide how it gets filed and how it gets found again. That is why this lesson calls memory the mind's filing system.
The three stages: encoding, storage, retrieval
Psychologists distinguish three necessary stages in the learning-and-memory process: encoding, storage, and retrieval. Encoding is the input stage — converting what you experience into a form the memory system can hold. Storage is keeping the encoded information over time. Retrieval is getting the information back out when you need it. Each stage gets its own lesson in this course; the point here is the pipeline itself. The stages are not neatly separate: how you encode information determines how it will be stored and which cues will work at retrieval, and the very act of retrieving can change a memory. A successful act of remembering needs all three working together.
The three-box model: sensory, short-term, long-term
In 1968, Richard Atkinson and Richard Shiffrin proposed the model of memory that still organizes introductory psychology: information passes through three distinct stages of storage — sensory memory, short-term storage, and long-term memory. Sensory memory holds raw sensory input very briefly, in a relatively unprocessed form — sights, sounds, and tastes for up to a couple of seconds. Original example: a sparkler traced through the dark leaves a glowing trail that lingers for a fraction of a second after the sparkler has moved on — sensory memory at work. short-term memory A temporary holding system for a limited amount of information, lasting roughly 10 to 30 seconds. Full entry → holds a limited amount of information for roughly 10 to 30 seconds. The closely related working memory The active form of short-term memory: holding information in mind while working with it, as when you multiply two numbers mentally. Full entry → is the version you actively use: holding a phone number in mind just long enough to dial it, and losing it the moment a friend interrupts with a question. Long-term memory is the relatively permanent store — skills and knowledge you can draw on hours, weeks, or years later. Original example: years after moving away, you can still describe the layout of your childhood kitchen. The honest note: the three boxes are a model, not a literal map of the brain. Later models, such as Baddeley and Hitch's working-memory framework, refined the original scheme. Use the boxes as thinking tools, not as anatomy.
Two kinds of long-term memory: explicit and implicit
Long-term memory splits into two broad kinds. explicit memory Long-term memory that can be consciously recalled and reported, such as facts and personal events. Full entry → is what you can consciously recall and report: facts about the world and events from your own life. Original example: you can say that Lima is the capital of Peru — a fact, which psychologists call semantic memory — and you can describe your cousin's wedding last spring — an event, called episodic memory. implicit memory Long-term memory that is not consciously recalled but is shown in performance, such as skills and habits. Full entry → is what you cannot consciously call up but that shows up in what you do: skills and learned habits. Original example: you can ride a bicycle without thinking about the balancing, and you cannot easily put the technique into words — the skill is demonstrated in the doing, not in the telling. Psychologists also call the explicit side declarative memory and the skill side procedural memory.
Why memory matters: identity and learning
Everything you know, and much of who you are, is assembled from stored and retrieved information. Your identity is largely a memory project: the episodes of your life are episodic memories, and the facts and words you think with are semantic memories. Original example: when a classmate asks how your summer went, you do not relive the summer; you retrieve a story you have stored, and that story is part of who you are. Learning depends on memory just as directly: a course is useful only to the extent that its content survives the semester. OpenStax puts it plainly: retrieving information from long-term memory is essential to everyday functioning, from brushing your teeth to driving to work.
The honest note: memory is reconstructive, not a recording
The reality check: memory does not work like a video camera. When you remember an event, you do not replay a stored file; you rebuild it from stored fragments plus general knowledge about how the world usually works. The APA Dictionary calls this reconstructive memory — remembering as the recreation of an experience that was only partially stored. Because rebuilding draws on expectations and later information, memories can be edited: two witnesses to the same moment can honestly remember different details. That is not a flaw; it is how the system works.
The honest framing: memory is the self's storage room
One image ties the lesson together: memory is the storage room the self lives out of. Your identity, your relationships, your skills, and your plans all draw on what is in that room — and the room is not a vault of untouched originals. Items are filed and refiled, rebuilt each time they are taken out. Knowing that does not make memory less impressive; it makes it more interesting. The filing system that builds your sense of self is the same system that occasionally loses a name at a party.
Eli explains
The same idea, in plain words
Explain it like I’m 10
Memory is the mind's filing system. Everything you experience arrives as raw moments, and the system has three jobs: turn a moment into something that can be filed, which is encoding; keep it, which is storage; and find it again when you need it, which is retrieval. Psychologists picture the system as three boxes. Sensory memory grabs a fraction of a second of raw input. Short-term memory holds a little information for a few seconds while you use it. Long-term memory keeps the things that matter for years. Long-term memory also comes in two flavors: explicit, the facts and stories you can call up on purpose, and implicit, the skills your body just knows. And one honest catch: the system does not replay memories like a video. It rebuilds them, a little differently each time.
Picture it like this
Think of a library run by one careful librarian. New information arrives like a book: the librarian decides how to catalog it — that is encoding — then shelves it — storage — and when you ask, finds it and brings it to the desk — retrieval. Some books sit in a reading-room cart for a few minutes before being shelved; that is short-term memory. The rest go into the stacks and stay for years; that is long-term memory.
Where the picture stops working
A library keeps books exactly as they were printed, but memory rebuilds a memory each time it is retrieved. A library catalog points to one fixed copy, while a memory can be reached through many cues and can shift with each telling. And the librarian always knows where everything is; the mind frequently cannot find what it knows is in there — the familiar tip-of-the-tongue moment has no library equivalent.
Worked example
Priya has a quiz on the water cycle on Friday. On Wednesday evening she reads the chapter, then explains the steps to herself in her own words and connects them to the rain that flooded the parking lot last week — that is encoding, and the personal connection helps the material stick. The next day passes, and the information stays put — storage. On Friday the quiz asks her to list the steps of the water cycle from memory, and she retrieves the sequence without notes. Two details from that quiz are worth noticing. She types her answers without thinking about where the keys are — implicit memory running the skill — and she writes 'the sun heats the ocean' with total confidence, a sentence she half-remembers from the book and half-rebuilds from watching steam rise off hot pavement after rain. Encoding, storage, retrieval, implicit skill, and a small reconstruction: one quiz, and the whole filing system was at work.
Key takeaway
Memory is the ability to store and retrieve information over time — the filing system that identity and learning run on. It works in stages and boxes, holds explicit facts and implicit skills, and rebuilds rather than replays the past.
Quick check
3 questions here, of 5 in this lesson’s practice set. Answers stay hidden until you check.
At a party, Ravi is introduced to a guest named Ines. He listens carefully, repeats her name to himself during the conversation, and two weeks later still greets her by name. Which sequence of stages did his memory use?
Choose an answer, then check it.
Nadia is waiting for a bus. As the bus pulls away, she catches the route number reflected in a shop window; the image lingers in her mind for less than a second before it fades. Which part of the three-box model is doing the work?
Choose an answer, then check it.
Study tools & related lessonsYou’ll learn to · Common mistakes · Easily confused · Key vocabulary · Related
You’ll learn to
- Define memory as the ability to store and retrieve information over time, and attribute the definition to the APA Dictionary of Psychology and OpenStax Psychology 2e.
- Name the three stages of memory — encoding, storage, and retrieval — with a one-line description of each.
- Explain the three-box model — sensory, short-term/working, and long-term memory — name its originators, and state honestly that it is a model rather than a literal place in the brain.
- Distinguish explicit from implicit long-term memory, using an original example of each.
- Explain why identity and learning depend on memory, using an original example.
- Analyze why psychologists describe memory as reconstructive rather than a recording, using an original example.
Common mistakes
"Memory is a single thing, like a video recorder that plays back what happened."
Memory is a set of processes — encoding, storage, retrieval — and a family of systems. There is no one storage place and no replay function; remembering rebuilds the past each time, which is why two witnesses can honestly remember different details.
"The three boxes — sensory, short-term, long-term — are actual rooms in the brain."
They are a model, proposed by Atkinson and Shiffrin, that organizes what researchers observe about how long and how much information is held. No surgeon has ever found a chamber labeled long-term memory; use the boxes as thinking tools.
"Short-term memory and working memory are exactly the same thing."
They are closely related but not identical. Short-term memory holds information briefly, while working memory is the active form that holds information and manipulates it, like keeping numbers in mind while adding them up.
"If someone can do something well, they should be able to explain how."
Not when the skill runs on implicit memory. Riding a bike or touch-typing is demonstrated in performance, not in explanation; the ability to do and the ability to describe draw on different memory systems.
"A confident memory must be an accurate one."
Confidence and accuracy are not the same thing. Because remembering is reconstructive, a vivid, confident memory can still contain details that were filled in rather than recorded.
Easily confused
Sensory memory vs. short-term memory and long-term memory
The three boxes differ in duration and capacity: sensory memory holds raw input for up to a couple of seconds, short-term memory holds a limited amount for roughly 10 to 30 seconds, and long-term memory holds skills and knowledge for years. Same pipeline, three very different holding patterns.
Explicit memory vs. implicit memory
Explicit memory can be consciously recalled and reported — facts and events; implicit memory shows up in performance without conscious recall — skills and habits. You can say what the capital of Peru is, but you cannot say how you balance on a bicycle.
Encoding vs. retrieval
Encoding gets information into the memory system and retrieval gets it back out. Both are required for a successful memory: information that was never properly encoded cannot be retrieved, and information that is stored but cannot be found is useless in the moment.
Key vocabulary
- memory
- The ability to store and retrieve information over time; psychologists treat it as a set of processes rather than a single thing.
- encoding
- The first stage of memory: converting experience into a form the memory system can hold.
- storage
- The second stage of memory: keeping encoded information over time.
- retrieval
- The final stage of memory: getting stored information back into awareness when it is needed.
- sensory memory
- A very brief, relatively unprocessed holding of sensory input, lasting up to a couple of seconds.
- short-term memory
- A temporary holding system for a limited amount of information, lasting roughly 10 to 30 seconds.
- working memory
- The active form of short-term memory: holding information in mind while working with it, as when you multiply two numbers mentally.
- long-term memory
- The relatively permanent store of skills and knowledge that can be drawn on hours, weeks, or years later.
- explicit memory
- Long-term memory that can be consciously recalled and reported, such as facts and personal events.
- implicit memory
- Long-term memory that is not consciously recalled but is shown in performance, such as skills and habits.
Sources & references
- Memory — APA Dictionary of Psychology — American Psychological Association
- Encoding — APA Dictionary of Psychology — American Psychological Association
- Storage — APA Dictionary of Psychology — American Psychological Association
- Retrieval — APA Dictionary of Psychology — American Psychological Association
- Sensory memory — APA Dictionary of Psychology — American Psychological Association
- Short-term memory — APA Dictionary of Psychology — American Psychological Association
- Long-term memory — APA Dictionary of Psychology — American Psychological Association
- Explicit memory — APA Dictionary of Psychology — American Psychological Association
- Implicit memory — APA Dictionary of Psychology — American Psychological Association
- Reconstructive memory — APA Dictionary of Psychology — American Psychological Association
- Psychology 2e, 8.1 How Memory Functions — OpenStax — OpenStax, Rice University
- Noba Project — Memory (Encoding, Storage, Retrieval) (Kathleen B. McDermott and Henry L. Roediger III, Washington University in St. Louis) — Noba Project (Diener Education Fund)
EliExplains lessons are original prose written from the open, credible references above. See Copyright & Licensing.
Researched 2026-08-22
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