The art of thinking · 3 · Memory

Long-term memory

Also known as: LTM, Declarative memory, Procedural memory

German: Langzeitgedächtnis

In cognitive psychology, long-term memory is the durable store of knowledge, experiences and skills, commonly divided into declarative memory — episodic memory for personal events and semantic memory for facts and concepts — and nondeclarative memory, including procedural memory for skills and habits.

Cognitive psychology
Memory

In one sentence

Long-term memory is the durable store of knowledge and skills: episodic and semantic (declarative) and procedural memory (Tulving 1972; Squire 2004).

Example

An operator remembers the last commissioning (episodic), knows what a safety PLC is (semantic) and switches the line to manual mode without thinking about the key sequence (procedural).

What the research shows

Richard C. Atkinson and Richard M. Shiffrin (1968) described long-term memory as a store of practically unlimited capacity, separate from short-term memory. Endel Tulving (1972) distinguished episodic memory, for events located in time and place, from semantic memory, for general knowledge. Larry R. Squire (2004) summarized the classification of memory systems based on patient and brain research: declarative memory (facts and events, dependent on medial temporal lobe structures) and nondeclarative memory (skills and habits, priming, conditioning). Frederic C. Bartlett (1932) and later Elizabeth F. Loftus and John C. Palmer (1974) showed that remembering is reconstructive: recall is shaped by knowledge and by the wording of questions, not replayed like a recording.

Evidence status

The distinctions between declarative and procedural memory and between episodic and semantic memory are well supported, though the boundaries between systems are debated and the systems interact. The reconstructive nature of memory is robust. Popular claims that memory works like a video recording, or that forgotten material is always stored somewhere and can be recovered, are not supported. Retrieval depends on cues and context; what is stored is not always accessible.

How it applies

Readers bring long-term knowledge to every page: what they know decides what they understand and what they can skip. Training builds that knowledge, documentation supports what cannot be expected to be remembered. The glossary “Applied cognitive psychology for information use” treats the design side, for example advance organizers and job aids. Required information for use must still be available at the point of use, whatever a reader may remember.

External references

How to read this pool

Entries, context cards and transitional topics

The art of thinking explains ways of thinking — where a method comes from, what it asks of you and how it was adapted later. You meet four kinds of content here, each with its own job:

Glossary entry: Defines one concept or method of thinking: its origin, an example and how it relates to neighboring ideas. “X vs. Y” sections set two methods side by side.
Context card of the art of thinking: A short, self-contained answer to one question about a way of thinking — its lineage, its steps, its limits. These cards are listed on The art of thinking only.
Transitional topicBridges both pools: A context card that bridges both pools: it shows how a way of thinking was adapted into documentation, analysis or quality practice. It sits with the reference context cards and is marked as transitional wherever it appears.
Reference entry or context card: Belongs to the Glossary & Norms Space on regulation, norms and engineering. Entries here link to one only where a method is also an established tool of documentation or quality work, such as the five whys or a user’s mental model.

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