Coding in STM
• Clues about coding 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
• Allan Baddeley:
Central
Executive
Articulatory
Loop
Visuospatial
Sketchpad
In general, how can we know if there are one,
two, or more independent systems handling
some aspect of perception or cognition?
Dissociations and DoubleDissociations
• Indicate that two processes or systems are
independent
Dissociations and DoubleDissociations
• A dissociation occurs when one process is
influenced by changing a variable but
another process is not
Dissociations and DoubleDissociations
• A dissociation occurs when one process is
influenced by changing a variable but
another process is not
• example: break the sparkplugs in your car
and examine the effect on a) your engine b)
your radio
Dissociations and DoubleDissociations
• A dissociation
Engine
Radio
Performance
Sparkplugs
Damage
Dissociations and DoubleDissociations
• A double-dissociation occurs when
changing a variable has different effects on
two different processes
• example: break sparkplugs vs break antenna
Dissociations and DoubleDissociations
Engine
Radio
Performance
Antenna
Sparkplugs
Damage
Dissociations and DoubleDissociations
Engine
Radio
Performance
Antenna
Sparkplugs
Damage
Working Memory “Modules”
• The logic of double-dissociation informs us
about working memory modules
A Modular Approach to STM
• Allan Baddeley:
Central
Executive
Articulatory
Loop
Visuospatial
Sketchpad
The article by Lee Brooks considers a double-dissociation
between Phonological and Visuospatial memory
representations
Coding in STM
• Modular Approach: Working Memory
• Allan Baddeley - two components of
Working Memory
• Evidence for a modular system:
– interference within modalities but not between
– example: subvocal counting of letters in a list
of words is very hard but subvocal counting of
the corners of a figure is easy
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”
• result:
Spatial Representation
(categorize corners)
Response
Time
Verbal Representation
(categorize nouns)
Verbal
Spatial
Response Modality
Working Memory “Modules”
• Interpretation:
– supports notion of modularity in Working
Memory (visuospatial sketchpad / articulatory
loop)
Next Time:
• Long-Term Memory
• Read Loftus for Next Thursday