Memory systems

• What kinds of things do we know?

• Is all memory the same?

• Types of memory systems

• Semantic and episodic memory.

Types of things we know

QuickTime™ and aPhoto - JPEG decompressor

are needed to see this picture.

QuickTime™ and aPhoto - JPEG decompressor

are needed to see this picture.

Is there just one memory system?• Are all of these types of memory the same?

• How do you learn a new skill?– How long does it take?– How do you study?– How long does the memory last– Are you conscious of retrieving the skill?

• How about learning a new fact?

• How about learning about an event you experience?

Maybe there isn’t just one LTM

• We will discuss many kinds of memory systems– Procedural vs. declarative memory– Episodic vs. semantic memory– Implicit vs. explicit memory

• These distinctions overlap somewhat

Questions to answer

• What kind of information is stored in that memory?

• How do you get information into the system?– How long does it take?

• How do you get memory out of the system?

• Are you conscious of the experience of retrieval?

• What brain regions are involved in that system?

Semantic and episodic memory

• One of the earliest distinctions to be made

• Semantic memory– Memory for facts, categories, and types of events

• Who is the President of the United States?

• What type of furniture do you sit on?

• What is this person doing?

Episodic memory

• Memory for things that happened to you.– What happened at a birthday party?– What did you eat for breakfast?– What did you see at the football game?

Structure of semantic memory• Semantic memory is organized around content

– The hierarchical model (Collins & Quillian)

Living Thing

Animal Plant

Mammal Bird

Dog

Cat

Lion Robin Canary

is - a

is - a

is - ais - a

is - a

is - ais - a

is - ais - a

has-part

Red Breast

has-part

Wings

Living Thing

Animal Plant

Mammal Bird

Dog

Cat

Lion Robin Canary

is - a

is - a

is - ais - a

is - a

is - ais - a

is - ais - a

has-part

Red Breast

has-part

Wings

Structure of semantic memory• Semantic memory is organized around content

– The hierarchical model (Collins & Quillian)

Living Thing

Animal Plant

Mammal Bird

Dog

Cat

Lion Robin Canary

is - a

is - a

is - ais - a

is - a

is - ais - a

is - ais - a

has-part

Red Breast

has-part

Wings

Living Thing

Animal Plant

Mammal Bird

Dog

Cat

Lion Robin Canary

is - a

is - a

is - ais - a

is - a

is - ais - a

is - ais - a

has-part

Red Breast

has-part

Wings

Nodes

Structure of semantic memory• Semantic memory is organized around content

– The hierarchical model (Collins & Quillian)

Living Thing

Animal Plant

Mammal Bird

Dog

Cat

Lion Robin Canary

is - a

is - a

is - ais - a

is - a

is - ais - a

is - ais - a

has-part

Red Breast

has-part

Wings

Living Thing

Animal Plant

Mammal Bird

Dog

Cat

Lion Robin Canary

is - a

is - a

is - ais - a

is - a

is - ais - a

is - ais - a

has-part

Red Breast

has-part

Wings

Nodes

Links

Structure of semantic memory• Semantic memory is organized around content

– The hierarchical model (Collins & Quillian)

Living Thing

Animal Plant

Mammal Bird

Dog

Cat

Lion Robin Canary

is - a

is - a

is - ais - a

is - a

is - ais - a

is - ais - a

has-part

Red Breast

has-part

Wings

Living Thing

Animal Plant

Mammal Bird

Dog

Cat

Lion Robin Canary

is - a

is - a

is - ais - a

is - a

is - ais - a

is - ais - a

has-part

Red Breast

has-part

Wings

Nodes

Links

Nodes and Links have Labels

Why does this makes sense?• Why should we think semantic memory

looks like this?

• Allows efficient storage of properties– Do rhinos have horns?– Do rhinos breathe?– Are rhinos made of molecules?

• We would not want to store every property with every concept.

• It would be useful to be able to derive some information.

Animal

Thing

Rhino

is-a

is-a

Animal

Thing

Rhino

is-a

is-a

Lexical Decision tasks

• Seeing one word prepares us to see related words.

NURSE DOCTOR

150ms

DOMTIR

DOUBLE

Related

Nonword

Unrelated

Episodic Memory• Some things are not facts.

A chairA chair

The time the dog sat in the chairThe time the dog sat in the chair

Episodic Memory• Some things are not facts.

A chairA chair

The time the dog sat in the chairThe time the dog sat in the chair

A factA fact

An episode of (someone’s) lifeAn episode of (someone’s) life

How is episodic memory structured?

• Tulving

• Organized chronologically– Think about what you did last weekend.

• Memory for sensations

• Truth is determined by personal belief

• Often requires deliberate access

• Admissable as eyewitness testimony– Only experts may testify about semantic memory

Studies of episodic memory

• Most memory studies tap episodic memory

• Recall and recognition– Do you remember this item from a particular

list you studied?– Do you recognize this item as one you saw on a

particular occasion?

Distinguishing types of memory

• Jacoby and Dallas (1981)

• Find a way to dissociate the types of memory– An episodic test that is influenced by a manipulation– A semantic test that is not

• Return to depth of processing– Episodic task: Recognition– Semantic task: Identify word from brief presentation

Test Type Appearance Sound MeaningSemantic 0.80 0.81 0.82

Episodic 0.50 0.63 0.86

Summary

• There are many types of memory

• Memory systems have different characteristics

• Semantic memory– Memory for facts, organized around content

• Episodic memory– Memory for events, temporal organization