Transcript Episodic memory

THE STORAGE OF OUR
EXPERIENCES
Chapter 13
A Fleeting Experience
2

The case of “Donald”
A
accidental blow to the head caused damage to
hippocampus.
 Severe memory problems
 Anterograde
amnesia: the inability to form long-term
memories.
 To
recall an event, the brain must:
 Store
the event as a memory
 Encode the memory into a meaningful form
 Retrieve the memory
Measures Of Memory
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
Explicit measures of human memory
An observable measure of the strength of a memory.
 Recall: requires the subject to access a memory.




Free recall
Cued recall
Recognition: judging whether information accurately reflects
a previous experience.


Yes/no recognition
Forced choice recognition
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
Implicit measures of human memory
A
measure that provides an indirect assessment of the
strength of a memory.
 Ebbinghaus’ (1885) savings score.
 Used
to measure memory.
 (# trials original learning required) – (# trials necessary to
relearn task)
 Reaction
time.
Taxonomy of Human Memory
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Procedural
automatic,
incremental,
unconscious
Motor Skills
Classical
Conditioning
Operant
Conditioning
Declarative
effortful,
can be conscious
Working vs.
Reference Memory
Episodic vs.
Semantic Memory
A Three-stage View of Memory
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

Atkinson & Shiffrin (1971)
Sensory register


The initial storage of memory for a very brief time as an
exact duplicate of the event.
Short-term store

A temporary storage facility where information is modified
to create a more meaningful experience.



Temporary and limited (typically 5 – 15 sec.)
Continued storage depends upon rehearsal and repetition.
Long-term store

Site of permanent memory storage.
A Rehearsal Systems Approach
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
Baddeley’s Rehearsal Systems Approach
 Inputs
retained in the sensory registers for analysis by
working memory.

Working memory
 Information
being actively processed by rehearsal
systems.

Reference memory

long term retention of events, relationships, and
procedures
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
Phonological loop
A
rehearsal system that holds and analyzes verbal
information.
 Evolved to facilitate the acquisition of language.
 Retains information in the verbal sensory system for a
about 2 sec. unless rehearsal keeps the information in
working memory.
 Probably not of great importance for a pigeon or
monkey
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
Visuospatial sketchpad
A
rehearsal system that holds and analyzes visual and
spatial information.
 Allows for people to acquire knowledge of the
appearance of objects and how to use those objects, as
well as spatial orientation and geographical
knowledge.
 Should be good in a pigeon and maybe a monkey
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
Central executive
 The
process that coordinates rehearsal systems and
retrieves memory from and transfers information to
permanent memory.
 Relies heavily on environmental cues to control
behavior.
 Can switch to an attentional supervisory control when
routine automatic control is insufficient.
 Is assumed to be a function of the frontal lobes.
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
Episodic buffer
 The
system that binds visual and verbal information in
the long-term store and retrieves information from the
short-term.
 Was a fourth component added by Baddeley to his
original conceptual framework of the working memory.
Short-term Store or Working Memory
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
Five major characteristics:
 Has
a brief storage span for new sesnory inputs
 Memories easily disrupted by new experiences.
 Storage capacity is limited
 Has a rehearsal function.
Working Memory in Animals
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food
Hunter (1913)
Working Memory or Body Orientation?
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food
Delayed Matching to Sample (DMTS)
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Comparison
Sample
Comparison
Delayed Matching to Sample (DMTS)
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PECK
PECK
FOOD
NO
FOOD
Symbolic Matching to Sample
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Symbolic Matching to Sample
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PECK
PECK
NO
FOOD
FOOD
NO
FOOD
FOOD
What is Learned in DMTS?
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a) General Matching Rule
Pigeon = No! (with few samples)
Cumming & Berryman (1965)
- Trained on Red, Green, Blue
- Failed to transfer to Yellow
b) Specific “If-Then Rules”
Symbolic Matching-To-Sample
- Learned as rapidly as Standard DMTS
Memory Coding
a) Retrospective = Backward Looking
b) Prospective = Forward Looking
Retrospective Code: IF
, Remember
Prospective Code: IF
, Remember
Roitblat, 1980
Confusion Errors?
1. between samples
2. between comparisons
Confusions:
Comparisons > Samples
Therefore:
Prospective Coding
Serial List Learning
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Present list of items to subject one at a time
A  B  C  D  E  F
Recall in any order
Serial List Learning
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Ask subject to recall or recognize a single item
Recency effect
Accuracy
Primacy effect
A
B
C
D
E
F
Humans:
Testing after a delay produces
a primacy effect
Accuracy
Accuracy
Testing immediately after list
produces a recency effect
A
B
C
D
E
F
What about in other animals?
A
B
C
D
E
F
Radial Arm Maze
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How Solved?
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
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Random Choice
Odour Trail
Patterned Responding
Working Memory*
12-Arm Radial Maze
Choices Prior to First Error
Mean Choices
8
6
4
2
0
1
3
5
7
Trial
9
11
13
12-Arm Radial Maze
Total Number of Errors
10
Mean Errors
8
6
4
2
0
1
3
5
7
Trial
9
11
13
Switch from retrospective to
prospective?
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12
1
11
2
10
3
9
8
4
7
5
6
Cook et al. (1985)
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

Rats removed after making 2, 4, 6, 8, or 10 choices
Shifting from retrospective to prospective midway
produces the lowest memory load (inverted Ushaped error curve)
Cook et al. (1985)
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Remember
Places Not Visited
Remember
Places Visited
Memory Coding
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a) Active = rehearse relevant information
b) Passive = gradual fading of a memory
trace
Human Forgetting Curve With No
Rehearsal
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Pigeon Forgetting Curve With Rehearsal
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Roberts, 1972
Directed Forgetting
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Sample
Remember
cue
Comparison
Forget
cue
peck
don’t
peck
ITI
Forget
cue
Delay
Least
peck
More
peck
Most
peck
Human Reference Memory
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

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Duration (relatively long-term)
Capacity (relatively large)
Forgetting (details lost, gist remembered)
Requires Consolidation
Retention of Fear Conditioning
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Clark’s Nutcracker
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Food Storing Bird
About 5,000 Caches
20 x 20 KM Area
9-month
Buried Under Snow
Sarah Shettleworth
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Results
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

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Birds recovered previously cached seeds and made
few errors
Didn’t find seeds hidden by experimenter
Didn’t return to the same site if first storing episode
is followed by a second storing episode
Summary of Animal Memory
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
Prospective and Retrospective 
Active not Passive

Reference memory

Duration and Capacity

Forgetting and Consolidation 
Working Memory
Episodic Versus Semantic Memories
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
Episodic memory
 The
memory of temporally related events, or the time
and place of an experience.

Semantic memory
 The
memory of knowledge concerning the use of
language and rules for the solution of problems or
acquisition of concepts..

The processes involved in storage and retrieval
differ between the two.
Do Animals have Episodic Memory?
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
Association of Events
 Episodic
associations are based on temporal
contiguity
 Semantic associations are based on the similarity of
meanings of events
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
Episodic memory system has limited inferential
capacity.
 Information
based mainly on sensory impressions.
 Recollection is deliberate and often requires conscious
effort.
 Dated Personal Memory (what, when, and where)
Western Scrub-Jay (Nicola Clayton)
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Clayton’s Results
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(Central Executive) Metamemory in Rats?
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
Knowledge of the state of one’s own memory
 for

example, memory strength
Foote and Crystal (2007)
 Duration
of noise sample, 2.00 to 3.62 = Left
 Duration of noise sample, 4.42 to 8.00 =Right
 Choice to continue → memory test, large reward
 Choice to bail-out → no test, small reward
Foote and Crystal (2007)
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Foote and Crystal (2007) Results
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Problems
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

Only 2 of 3 rats showed positive results (5 others
always bailed or always decided)
Maybe they learned to bail with feedback on the
“close” duration values?