Types of Long-Term Memory

The Multi-Store Model treats long-term memory (LTM) as a single, unitary store. However, research has shown that LTM is actually composed of several distinct types, each with different characteristics, functions, and neural substrates. Endel Tulving (1985) proposed the most influential distinction, identifying three types of LTM: episodic, semantic, and procedural memory.

Key Definition: Long-term memory (LTM) is the permanent memory store that has potentially unlimited capacity and duration. It includes episodic, semantic, and procedural memory.

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Tulving's Three Types of LTM (1985)

1. Episodic Memory

Key Definition: Episodic memory refers to the ability to recall personal events and experiences from one's own life. These memories are "time-stamped" — they include information about when and where the event occurred, and the emotions associated with it.

Feature	Detail
Content	Personal events and experiences (e.g., your first day at school, a holiday, a conversation)
Time-stamped	Memories include a record of when the event happened and its temporal context
Contextual	Includes details of where the event occurred and who was there
Emotional	Often accompanied by emotional associations (e.g., happiness, embarrassment)
Conscious recall	Requires conscious, deliberate effort to retrieve — you must "mentally travel back in time"

Example: Remembering your last birthday party — where it was held, who attended, what you ate, how you felt.

2. Semantic Memory

Key Definition: Semantic memory is our store of general knowledge about the world, including facts, concepts, and the meanings of words. Unlike episodic memory, it is not linked to a specific time or place.

Feature	Detail
Content	Facts, concepts, meanings, and general knowledge (e.g., "London is the capital of England")
Not time-stamped	Not tied to a specific personal experience or time
Abstract	Knowledge that exists independently of personal context
Less personal	Shared knowledge — the same facts are held by many people
Conscious recall	Also requires conscious effort but does not involve reliving a personal experience

Example: Knowing that Paris is the capital of France, or knowing what the word "democracy" means.

3. Procedural Memory

Key Definition: Procedural memory is our memory for how to do things — skilled actions and learned behaviours. It is implicit (unconscious) and does not require conscious recall.

Feature	Detail
Content	Motor skills and learned actions (e.g., riding a bicycle, typing, playing the piano)
Implicit	Operates without conscious awareness — you do not need to think about each step
Difficult to verbalise	Hard to explain to others in words (try explaining how to ride a bicycle!)
Resistant to forgetting	Once established, procedural memories are very durable and can last a lifetime
Automatic	Become automatic with practice — require little cognitive effort once learned

Example: Riding a bicycle — even after years of not cycling, the skill is usually retained.

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Comparison of the Three Types

Feature	Episodic	Semantic	Procedural
Content	Personal events	Facts and knowledge	Skills and actions
Time-stamped?	Yes	No	No
Conscious?	Yes (explicit)	Yes (explicit)	No (implicit)
Verbalised?	Easily	Easily	With difficulty
Example	Your 18th birthday	Knowing 2 + 2 = 4	Riding a bicycle
Brain area	Prefrontal cortex, hippocampus	Temporal lobe (especially anterior and lateral)	Cerebellum, basal ganglia, motor cortex

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Evidence for Different Types of LTM (AO3)

Case Study Evidence

The strongest evidence comes from patients with brain damage who show dissociations — impairment of one type of LTM while other types remain intact.

HM (Henry Molaison):

• After bilateral removal of his hippocampus, HM could not form new episodic memories (anterograde amnesia for personal events).
• His semantic memory was partially impaired — he could not learn many new facts after his surgery, but his pre-existing semantic knowledge was largely intact.
• His procedural memory was intact — he could learn new motor skills (e.g., mirror drawing) and improve with practice, even though he had no episodic memory of having practised before.