Long-term Memory

Long-term memory is the relatively permanent storage system in the Atkinson-Shiffrin model, holding information with virtually unlimited capacity and duration; it includes explicit memories (episodic and semantic) and implicit memories (like procedural skills).

Verified for the 2027 AP Psychology examLast updated June 2026

What is Long-term Memory?

Long-term memory (LTM) is the final stop in the Atkinson-Shiffrin three-stage model. Information flows from sensory memory to short-term memory, and if it gets encoded deeply enough, it lands in long-term storage. Unlike short-term memory, which holds a few items for seconds, LTM has no known capacity limit and can hold information for a lifetime. Your phone's storage fills up. Yours doesn't.

LTM isn't one big bucket, though. It splits into explicit (declarative) memory, the stuff you can consciously state, and implicit (nondeclarative) memory, the stuff you just do. Explicit memory breaks down further into episodic memory (personal experiences, like your first day of high school) and semantic memory (facts, like knowing the hippocampus consolidates memories). Implicit memory includes procedural memory, which is why you can still ride a bike after years away from one. Getting information into LTM requires encoding, and getting it back out requires retrieval, which means LTM connects to basically every topic in the memory sequence.

Why Long-term Memory matters in AP Psychology

Long-term memory anchors the entire memory sequence in the course, from 5.1 Introduction to Memory through 5.6 Biological Bases of Memory. It's the destination that encoding (Topic 5.2) and storing (Topic 5.3) work toward, the source that retrieval (Topic 5.4) pulls from, and the system where forgetting and distortion (Topic 5.5) go wrong. The biological side matters too. Consolidation, the process of stabilizing a memory into long-term storage, depends on the hippocampus, and disruptions to it (like sleep deprivation or Alzheimer's disease) show up in both MCQs and research-design questions. If you can't sort a scenario into the right type of long-term memory, half of the memory questions on the exam become guesswork.

How Long-term Memory connects across the course

Baddeley's Working Memory Model (Unit 5)

Working memory is the active workspace that decides what makes it into long-term storage. Think of working memory as the loading dock and LTM as the warehouse. Information that gets rehearsed and elaborated in working memory gets shelved; everything else gets tossed.

Episodic, Semantic, and Procedural Memory (Unit 5)

These are the subtypes living inside long-term memory, and the exam loves making you sort scenarios into them. Remembering your graduation is episodic, knowing the capital of France is semantic, and tying your shoes is procedural. Same warehouse, different aisles.

Biological Bases of Memory (Unit 5)

Long-term memories aren't stored the instant you experience something. The hippocampus consolidates them over time, and sleep is when much of that consolidation happens. That's why a practice-question favorite is designing an experiment testing sleep deprivation's effect on long-term memory consolidation.

Alzheimer's Disease and Acetylcholine (Unit 5)

Alzheimer's shows what happens when the biology of long-term memory breaks down. Damage to acetylcholine-producing neurons and hippocampal regions erodes explicit memories first, while procedural memories often survive longer. That dissociation is evidence that LTM has separate systems, not one storage tank.

Is Long-term Memory on the AP Psychology exam?

Multiple-choice questions usually test long-term memory in one of three ways. First, classification: a scenario describes someone remembering how to ride a bike after years, and you pick procedural memory. Second, the model: questions ask how sensory memory, short-term memory, and long-term memory fit together in the Atkinson-Shiffrin model. Third, biology and research design: identifying consolidation in a scenario, or evaluating an experiment on sleep deprivation and memory consolidation. On the free-response side, memory concepts show up embedded in research scenarios, like the 2021 SAQ where Mr. Gomez tests study techniques with his math class. There you have to apply memory and methods vocabulary to a study, not just define terms. The move that earns points is naming the specific subtype or process (episodic, procedural, consolidation, encoding) instead of just saying "long-term memory."

Long-term Memory vs Short-term memory

Short-term memory holds about 7 (plus or minus 2) items for roughly 20-30 seconds without rehearsal. Long-term memory has virtually unlimited capacity and can last a lifetime. The trap on MCQs is duration-based scenarios. If someone holds a phone number just long enough to dial it, that's short-term. If they recall it a week later, it made it into long-term storage. Also don't confuse short-term memory with working memory; working memory is the updated, active-processing version of the short-term stage.

Key things to remember about Long-term Memory

  • Long-term memory is the third stage of the Atkinson-Shiffrin model and has virtually unlimited capacity and duration.

  • Long-term memory divides into explicit memory (episodic experiences and semantic facts) and implicit memory (including procedural skills like riding a bike).

  • Consolidation, which depends heavily on the hippocampus and on sleep, is the process that stabilizes information into long-term storage.

  • Getting into long-term memory requires deep encoding, and getting information back out requires retrieval cues, so LTM links Topics 5.2 through 5.5 together.

  • Long-term memories are reconstructive, not exact recordings, which is why forgetting and memory distortion still happen even with unlimited storage.

  • Alzheimer's disease damages explicit long-term memory while often sparing procedural memory, which is evidence that LTM contains separate systems.

Frequently asked questions about Long-term Memory

What is long-term memory in AP Psychology?

Long-term memory is the relatively permanent storage stage of the Atkinson-Shiffrin model, with virtually unlimited capacity and duration. It includes explicit memories (episodic and semantic) and implicit memories (like procedural memory).

Is long-term memory really unlimited?

Capacity-wise, yes, there's no known storage limit. But unlimited storage doesn't mean perfect access. Retrieval failure, decay of retrieval cues, and memory distortion mean you can "have" a memory and still fail to recall it accurately.

What's the difference between long-term memory and short-term memory?

Short-term memory holds about 7 plus or minus 2 items for roughly 20-30 seconds without rehearsal; long-term memory holds unlimited information potentially for a lifetime. Information moves from short-term to long-term storage through encoding and consolidation.

What part of the brain stores long-term memories?

The hippocampus consolidates new explicit memories, but the memories themselves end up distributed across the cortex. Procedural memories rely on different structures, which is why Alzheimer's patients can lose facts and experiences while still performing well-practiced skills.

Are long-term memories like video recordings?

No. Long-term memories are reconstructed each time you retrieve them, which makes them vulnerable to distortion and misinformation. This is exactly why research doesn't support using hypnosis to retrieve accurate memories.