Opportunities for extra credit:
Keep checking at:
www.tatalab.ca
Upcoming
March 22
March 24
More about conscious
perception
Overview of Memory
Sensory Memory
March 29
March 31
Short-Term/Working
Memory (Brooks expt. 1)
Long-Term Memory
April 5
April 7
NO CLASS
Long-Term Memory and
False Memories (Loftus)
April 12
Consciousness and
“Perception without
Awareness”
April 14
Subliminal Messages (Vokey
and Read)
Memes (Dawkins)
“Types” of Memory
• Sensory Memory
– brief ( < 1 second)
– preattentive / parallel processing (very
large capacity)
Overview of Memory
RETRIEVAL
• Atkinson-Shiffrin Model
ATTENTION
Sensory
Signals
Sensory
Memory
Short-Term
Memory
Long-Term
Memory
REHEARSAL
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 ?!
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”
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
• Clues about coding in STM:
– # of items stored in STM depends on rate of
speech
Coding in STM
• Clues about coding in STM:
– # of items stored in STM depends on rate of
speech
– phonological similarity effect: similar sounding
words are harder to store/recall than different
sounding words
Coding in STM
• Clues about coding in STM:
– # of items stored in STM depends on rate of
speech
– phonological similarity effect: similar sounding
words are harder to store/recall than different
sounding words
What does this suggest about the nature of information in STM?
Coding in STM
• It seems that information can be stored in a
linguistic or phonological form
Coding in STM
• It seems that information can be stored in a
linguistic or phonological form
Must it be stored this way?
Coding in STM
• It is also possible to “keep in mind” nonverbal information, such as a map
Are there two different STM systems?
A Modular Approach to STM
Central
Executive
Articulatory
Loop
Visuospatial
Sketchpad
Experiment 1 in the article by Lee Brooks
demonstrates a double dissociation between
Articulatory Loop and Visuospatial Sketchpad
Working Memory “Modules”
• Lee Brooks: interference between different
representations in STM (Experiment 1)
– Memory Representation
• verbal task: categorize words in a sentence
• spatial task: categorize corners in a block letter
– Response Modality
• verbal response: say “yes” or “no”
• spatial response: point to “yes” or “no”
Working Memory “Modules”
• Verbal Task: indicate if each word is or is not a
noun
– “I went to the store to buy a loaf of bread.”
–N N
N N Y N N N Y N Y
Working Memory “Modules”
• Spatial Task: indicate if each corner points
outside
Y
Y
F
Y
N
Working Memory “Modules”
• In both tasks the information needed must be
maintained (represented) in working memory
Working Memory “Modules”
• Response Modalities:
Verbal
Spatial
Say: “yes” “no” “no”
Point to: Y or N
Y
Y
Y
Y
Y
N
N
N
N
N
Working Memory “Modules”
• Both response modalities also engage working
memory
Working Memory “Modules”
• Prediction:
– There should be interference when response modality
and task representation engage the same module
– if there is only one kind of module, then there should
be interference between every pairing of
representation to response
Working Memory “Modules”
• result: a cross-over interaction (double dissociation
Performance
Verbal Representation
(categorize words)
Spatial Representation
(categorize corners)
Verbal
Spatial
Response Modality
Working Memory “Modules”
• Interpretation:
– supports notion of modularity in Working
Memory (visuospatial sketchpad / articulatory
loop)