Memory
Short term memory
(a.k.a. Working Memory)
Course Overview
Knowledge
Acquisition
(perception)
ch. 3: Vision. How are
objects recognized?
-It looks easy but it’s not
Ch. 6-11: Memory
- to know is
to remember
- Different types of
ch.4: Attention.
-Filters perceptual input
Ch. 12-14:
Reasoning
- inductive
- deductive
knowledge (visual K,
language, categories) Problem Solving
ch. 5: Working Memory - Deficits & Errors
- Buffer for mental
representations
Emotion
Use
The Brain
Ch 4:Executive
Functions
Free Recall Task
Subjects:
- hear items (usually 10-40 words), then
- they say or write all the items they can
remember, in any order.
Serial Position Function
Probability
of reporting
the item
?
12
………
Position in Original List
1. Monster
2. Camera
3. Tricycle
4. Melon
5. Window
6. Guest
7. Quiet
8. Cherish
9. Waiting
10. Rabbitt
11. Computer
12. Child
13. Chicken
14. Ghost
15. Slave
30
distinctiveness
Villanova
Primacy
Recency
Privileged rehearsal
better LTM encoding
STM contribution
(Glanzer & Kunitz, 1966)
List Length
20
30
10
20
Position in Original List
30
40
Prob.
Of
Rept.
1
40
Serial position effects are consistent over different list sizes...
“Modal Model” (Atkinson & Shiffrin, 60’s)
STM
LTM
early sensory
processing
•Very rapid decay
•Unlimited capacity
• Consciously available •Hard to get stuff into it.
•Organized semantically
• Flexible material
(1-2 secs)
•Fixed # of slots
•Modality specific
(7+2 chunks)
•Decays if not rehearsed
(iconic, echoic)
•Vulnerable
Memory Processes
Sensory
Memory
• Attention
Short-term
Working
Memory
Long-term
Memory
Memory Processes
Sensory
Memory
• Storage
Short-term
Working
Memory
Long-term
Memory
Memory Processes
Sensory
Memory
• Retrieval
Short-term
Working
Memory
Long-term
Memory
Memory Processes
Sensory
Memory
Short-term
Working
Memory
• Information loss/ Forgetting
Long-term
Memory
Memory Processes
Sensory
Memory
Short-term
Working
Memory
• Rehearsal, Elaboration, etc.
Long-term
Memory
Modal Model: Primacy and Recency Effects
STM
LTM
early sensory
processing
•Very rapid decay
•Unlimited capacity
• Consciously available •Hard to get stuff into it.
•Organized semantically
• Flexible material
(1-2 secs)
•Fixed # of slots
•Modality specific
(7+2 chunks)
•Decays if not rehearsed
(iconic, echoic)
•Vulnerable
STM
LTM
Recency
Primacy
STM
(Murray Glanzer)
(Murray Glanzer)
LTM
Independence of LTM and STM:
Neurological evidence
Patient H.M.
- surgery in 1953 to relieve epilepsy.
- Normal working memory: normal digit span
- Impaired Long-term memory (anterograde amnesia): unable to learn
most new information. he can recall facts from before surgery (events from school
days, preserved language skills, recognized people).
Patient K.F.
- closed head injury.
- Impaired working memory: Digit span of 1 item
- Normal Long-term memory (recall a short story, learn word lists when
lists presented repeatedly, and do fine on long-term recognition).
(Alan Baddeley)
Prob.
Of
Rept.
Normals
STM Patients
Position
Anterograde Amnesia
might be explained as a
blockage of the flow of
information from STM
to LTM
Sensory
LTM
STM
BUT…short term memory deficits in the absence
of LTM deficits spell trouble for this gateway
model of LTM acquisition...
Sensory
LTM
STM
Entry into STM is not necessary for entry into LTM
Impairment
• Double dissociations guard against resource
artifacts (differences in task performance that
stem from differences in task difficulty)
• For example,
– I can juggle 3 balls, but
– I cannot juggle 5 balls,
• Should we conclude that juggling 3 balls is a
process independent from juggling 5? Or that
juggling 5 balls is a more difficult task?
– We’ll argue for independence only if we find
someone who is unable to juggle 3 balls but can
juggle 5 (double dissociation). Quite unlikely :-)
Double dissociations guard against resource
artifacts (differences in task performance that
stem from differences in task difficulty)
For example, Patient H. M. has:
- impaired LTM but,
- normal STM
Should we conclude that LTM is a process independent
from STM? Or that LTM is a more difficult task?
We’ll argue for independence only if we find
someone who is unable to hold things in STM but
can retain them in LTM (patient K.H.).
Working Memory
• A cognitive system that allows the
maintenance of information on line or
available for immediate processing.
Model of Memory
Sensory
Memory
F
I
L
T
E
R
Short-term
Working
Memory
Long-term
Memory
Model of Memory
Visual
Sensory
Memory
F
I
L
T
E
R
Central
Exec.
Auditory
Long-term
Memory
Working Memory
(Alan Baddeley)
Visuospatial
Buffer
Central
Executive
Phonological
Buffer
Short-Term Memory for Visual and
Verbal Materials: One or two stores?
Approach 1: Store maximum capacity
of one type -- then see if person can
remember any of the other type.
Example:
3982174
+
Usual Finding:
ZERO interference between verbal and
visual STM loads
(Sanders & Scarborough)
Working Memory
(Alan Baddeley)
Visuospatial
Buffer
Central
Executive
Phonological
Buffer
The phonological buffer
Phonological
short-term store
Verbal information
subvocal
rehearsal
process
Phonological Buffer: Evidence
• Task: Memory Span
– Listen a list of items, and repeat them
• Effect of:
– Phonological Similarity (phono store)
– Articulatory suppression (subvocal rehearsal)
– Word length (subvocal rehearsal)
• Neurological overlap with language areas
Phonological Similarity
Confusions occur if words sound alike:
mad, cat, man, map, cat
But not for similar meaning:
huge, long, tall, big, wide
or for similar-looking:
bough, cough, dough, through
Articulatory Suppression
repeatedly say “the” while hearing a list
B C P T V
B K X Y R
“the the the the the the the the”
Word length effect
People can generally remember about as many words
as they can say in 2 seconds.
memory span for “sum, wit, harm”
better than for “opportunity, individual, university”
Same number of chunks…but one of the sets takes
longer to articulate.
This result provides support for the notion of
articulatory rehearsal of phonological information.
Neural overlap between verbal WM and language
Speech production areas and language receptive areas are active
when people try to remember phonological information
Phonological Buffer
• The contents of storage is limited by:
– the time it takes to rehearse the items
– the number of “chunks” encoded
Chunking and the capacity of the phonological buffer
The standard estimate of the capacity of the phonological
buffer is 7 plus or minus 2 “chunks” of information.
A chunk is a meaningful unit of information.
In a typical digit span task, subjects can hear and report
back about 5-9 randomly selected digits.
F B I C I A F D R J F K
F B I
C I A
F D R
J F K
chunking allows storage of greater amounts of
information…because information is
“packaged” more efficiently
Working Memory
(Alan Baddeley)
Visuospatial
Buffer
Central
Executive
Phonological
Buffer
rehearsal
?
storage
Brain Activations during
Spatial and Object Working Memory
It appears that
different brain
regions are active
during the storage
of spatial and
object information
in working
memory.
Spatial
Object
Double Dissociation based on
Brain Localization
Task A
Task B
System A
Brain region A
Brain region B
System B
Brain region A
Brain region B
Working Memory
Visuospatial
Buffer
Central
Executive
Phonological
Buffer
spatial
rehearsal
object
storage
The Central Executive
• Supervise attention
• Planning/Coordination
• Monitoring
the least well understood aspect of working memory.
Frontal lobe syndrome
• Distractibility, difficulty concentrating
• Problems with organization, planning
• Perseveration: fail to stop inappropriate
behavior