Change of Plans:
Read Intro and Expt. 1 in article by
Lee Brooks for Wed.
Read Beth Loftus for Monday Nov.
29th
Memory
Short-Term “Working” Memory
Overview of Memory
RETRIEVAL
• Atkinson-Shiffrin Model
ATTENTION
Sensory
Signals
Sensory
Memory
Short-Term
Memory
Long-Term
Memory
REHEARSAL
Short-Term Memory
• process by which we hold information “in
mind”
Short-Term Memory
• process by which we hold information “in
mind”
• example: temporarily remembering a phone
number
Characteristics of STM
•
Capacity? Duration?
•
How could you measure these
parameters?
Characteristics of STM
•
Limited Duration
–
Brown-Petersen Task:
• subject is given a trigram (e.g. C-F-W) to
remember
• vocal rehearsal is prevented by counting
backwards
• recall accuracy tested as a function of
retention interval
Characteristics of STM
•
STM
decays
over
seconds
Characteristics of STM
•
Limited Duration
–
Brown-Petersen Task Interpretation: rapid
loss of information in STM (over a period of
seconds…much longer than sensory memory)
Characteristics of STM
•
Limited Capacity
–
How might you measure capacity?
Characteristics of STM
•
Limited Capacity
–
–
George Miller
Subject is given longer and longer lists of tobe-remembered items (words, characters,
digits)
Characteristics of STM
•
Limited Capacity
–
–
–
George Miller
Subject is given longer and longer lists of tobe-remembered items (words, characters,
digits)
Result: Subjects are successful up to about 7
items
Characteristics of STM
•
Limited Capacity
–
What confound must be considered ?!
Characteristics of STM
•
Limited Capacity
–
–
What confound must be considered ?!
Recalling takes time !
Characteristics of STM
•
Limited Capacity
–
–
–
–
What confound must be considered ?!
Recalling takes time !
It seems that the “capacity” of STM (at least
measured in this way) depends on the rate of
speech - faster speech leads to apparently
larger capacity
Some believe capacity is “2 - 3 seconds worth
of speech”
Characteristics of STM
•
Limited Capacity
– “chunking”: grouping items into
meaningful bundles increases STM
capacity (in some sense)
– Example: 111 333 666 333 777 222
Forgetting from STM
• Why do we “forget” from STM?
– Does the memory trace decay?
• not likely because with very small lists (like 1 item)
retention is high for long intervals
Forgetting from STM
• Why do we “forget” from STM?
– Does the memory trace decay?
• not likely because with very small lists (like 1 item)
retention is high for long intervals
– Instead, it seems that information “piles up”
and begins to interfere
Forgetting from STM
• Interference in STM is complex and
specific
Forgetting from STM
• Interference in STM is complex and
specific
• For example, severity of interference
depends on meaning
Forgetting from STM
• Interference in STM is complex and
specific
• For example, severity of interference
depends on meaning
– Subjects are given successive recall tasks with
list items from the same category (e.g. fruits)
– final list is of either same or different category how is good is recall on this list?
Forgetting from STM
• Accuracy rebounds if category changes
Coding in STM
• How is information coded in STM?
Coding in STM
• How is information coded in STM?
• Failures of STM give some clues:
Coding in STM
• How is information coded in STM?
• Failures of STM give some clues:
– Capacity decreases with increasing length of tobe-remembered words
Coding in STM
• How is information coded in STM?
• Failures of STM give some clues:
– Capacity decreases with increasing length of tobe-remembered words
– phonological similarity effect - similar
sounding items are harder to remember than
different sounding items
Coding in STM
• How is information coded in STM?
• Failures of STM give some clues:
– Capacity decreases with increasing length of tobe-remembered words
– phonological similarity effect - similar
sounding items are harder to remember than
different sounding items
• What does this suggest about coding in
STM?
Coding in STM
• Information in STM can be coded in an
“auditory” (or subvocal) way
• Try to sketch a model of STM with boxes
and arrows