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” non-verbal information, such as a map

Are there two different STM systems?

A Modular Approach to STM

• Allan Baddeley:

Articulatory Loop

Central Executive

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 Double-Dissociations

• Indicate that two processes or systems are independent

Dissociations and Double-Dissociations

• A dissociation occurs when one process is influenced by changing a variable but another process is not

Dissociations and Double-Dissociations

• 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 Double-Dissociations

• A dissociation

Performance

Damage

Sparkplugs

Engine

Radio

Dissociations and Double-Dissociations

• A double-dissociation occurs when changing a variable has different effects on two different processes

• example: break sparkplugs vs break antenna

Dissociations and Double-Dissociations

Performance

Damage

Sparkplugs

Engine

Radio

Antenna

Dissociations and Double-Dissociations

Performance

Damage

Sparkplugs

Engine

Radio

Antenna

Working Memory “Modules”

• The logic of double-dissociation informs us about working memory modules

A Modular Approach to STM

• Allan Baddeley:

Articulatory Loop

Central Executive

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:

Response Time

Response Modality

Verbal Spatial

Spatial Representation(categorize corners)

Verbal Representation(categorize nouns)

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