Read: Loftus for Tuesday Vokey for April 14 Idea Journals due on the 16th.

Read:

Loftus for Tuesday

Vokey for April 14

Idea Journals due on the 16th

Overview of Memory

• Atkinson-Shiffrin Model

Sensory Signals

Sensory Memory

Short-Term Memory

Long-Term Memory

ATTENTION

REHEARSAL

RETRIEVAL

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

• Duration? Capacity?

• How could one measure these parameters?


• 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


• STM decays over seconds


• Limited Duration– Brown-Petersen Task Interpretation: rapid

loss of information in STM (over a period of seconds…much longer than sensory memory)


• Limited Capacity– How might you measure capacity?


• Limited Capacity– George Miller – Subject is given longer and longer lists of

to-be-remembered items (words, characters, digits)


• Limited Capacity– George Miller – Subject is given longer and longer lists of

to-be-remembered items (words, characters, digits)

– Result: Subjects are successful up to about 7 items


• Limited Capacity– What confound must be considered ?!


• Limited Capacity– What confound must be considered ?!– Recalling takes time !


• 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


• For example, severity of interference depends on meaning

Forgetting from STM


• 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


of speech– phonological similarity effect: similar

sounding words are harder to store/recall than different sounding words

Coding in STM


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

Articulatory Loop

Central Executive

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”


• 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


• Spatial Task: indicate if each corner points outside

FY Y

Y

N


• In both tasks the information needed must be maintained (represented) in working memory


• Response Modalities:

Say: “yes” “no” “no” Point to: Y or N

Verbal Spatial

Y NY NY NY NY N


• Both response modalities also engage working memory


• 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


• result: a cross-over interaction (double dissociation

Per

form

ance

Response Modality

Verbal Spatial

Spatial Representation(categorize corners)

Verbal Representation(categorize words)


• Interpretation:– supports notion of modularity in Working

Memory (visuospatial sketchpad / articulatory loop)

Read: Loftus for Tuesday Vokey for April 14 Idea Journals due on the 16th.

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