Working memory

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Working memory
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Traditional Model of Memory

• Atkinson Shiffrin (1968) 3 Stage Model

Short Term Memory (STM)
Long Term Memory (LTM)
Sensory registers
Stimuli
Information Processing Model
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What is short-term memory (STM) for?

• Is STM for transferring information to long-term
  memory (LTM)?
• Is it a passive terminal for information
  transfer?

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Working memory Conceptual Background
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Working memory

• STM is a temporary storage of information.
• STM is a temporary buffer (control center) of
  information.

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Temporary storage

• Questions
• From New York to Pittsburgh, it takes about
  7hours and 30 minutes by car. From Pittsburgh to
  Chicago, it takes about 8hours and 30 minutes by
  car. How long does it take from New York to
  Chicago, if you want to drive through Pittsburgh?
  Easy Ah?
• Tom is taller than Jane. Jane is shorter than
  Steve. Lisa is taller than Steve and Tom. And
  Steve is shorter than Tom. Is Jane shorter than
  Tom?

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Raven test
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Raven test (Carpenter, Just, Shell, 1990)
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(No Transcript)
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• (2 x 6) -10 ?
• 3 4 3 x 3 ?

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• Do the following calculations while you keep
  pronouncing the, the,
• (3 x 5) -10 ?
• 2 5 - 3 x 3 ?

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Demonstration
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Task 1

• Find the answer to the following question as
  quickly and accurately as possible.

Lucy came before Jane. Kathy arrived after Jane.
Suzy came before Lucy. Who came first? Who
came second?
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Task 2

• Find the answer to the following question as
  quickly and accurately as possible. While you
  are looking for the question, please keep saying
  the-the-the-the.

Tom arrived after Steve. John came before Steve.
Mike arrived before John. Who came first? Who
came second?
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• Bill went to dinner and met Jane. They decide to
  share their French Fries and coke. After the
  dinner, they left the cafeteria and spend some
  time in a library together. After going over
  some review notes for their Sociology class, they
  went to the movies together. Later, Steve saw
  Jane sitting in a lounge and talking with Bill.
  Are Bill and Jane friends?

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Temporary storage of information

• How do we solve these questions?
• In order to answer these questions, you need
  temporary storage of information.
• STM? working memory
• Working memory ? a buffer for information
  manipulation

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Computer metaphor

• Working memory ? Random Access Memory (RAM)
• 128MB
• Long-term memory
• Hard disk, Zip disk
• After shutting down your computer, you lose the
  information stored in RAM.
• But the infor. stored in your hard disk is OK.

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Do we have RAM (Working memory)?

• Do we have working memory as we have RAM in our
  computer?

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Operation Span Experiment (CogLab CD)
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Baddeleys dual task experiments

• Test the idea that short-term memory is not just
  for transferring information to LTM.
• It is for a working buffer (to manipulate
  information) for many cognitive activities.

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Working memory

• If there is something called working memory,
  what is it?
• How does it encode and manipulate information?
• How does it transfer information to LTM?
• What is the capacity? (128MB?)

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Hypothesis

• We use Short-term memory for Working memory

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Baddeleys experiments

• Procedure 1 (control condition)
• The subject was given items to remember (e.g., a
  sequence of numbers or letters)
• The subject report the item given in the first
  task (recalling).
• The subject carried out a cognitive task (e.g.,
  verifying a sentence)

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• Procedure 2 (Experimental condition)
• The subject was given items to remember (e.g., a
  sequence of numbers or letters)
• The subject carried out a cognitive task (e.g.,
  verifying a sentence)
• The subject report the item given in the first
  task (recalling).
• (Baddeley Hitch, 1974)

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Design
Experimental condition
Control condition
Memory encoding
Memory encoding
Memory retrieval (recall)
A sentence verification task
A sentence verification task
Memory retrieval (recall)
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Tasks

• Memory task
• Briefly present a list of digits (414321090) to
  the subject.
• The subject recalls the digits as accurately as
  possible.

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• Sentence verification task
• A is preceded by B. AB? ? yes/no
• C follows D. DC? ? yes/no

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Experimental Condition

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• Memorize
• 756923

Memorize 182732
Memorize 094722
A is preceded by B. AB Yes or No?
D comes before C. CD Yes or No?
D is ahead of A. DA Yes or No?
Recall the number
Recall the number
Recall the number
Memorize 672392
Memorize 108223
Memorize 33598
Q follows J. QJ Yes or No?
B is before T. TB Yes or No?
E appears before O OE Yes or No?
Recall the number
Recall the number
Recall the number
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Control Condition
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• Memorize
• 238646

Memorize 521890
Memorize 122649
T is preceded by I. IT Yes or No?
D comes before U. UD Yes or No?
D is ahead of O. DO Yes or No?
Recall the number
Recall the number
Recall the number
Memorize 589886
Memorize 332189
Memorize 443284
Q follows N. NQ Yes or No?
B is before Y. YB Yes or No?
E appears after C CE Yes or No?
Recall the number
Recall the number
Recall the number
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What is the difference between the two conditions?

• The memory task is divided by the verification
  task in the experimental condition.
• The memory task is not divided by the
  verification task in the control condition.

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Why is this difference important?

• Test
• Short-term memory is used as working memory.

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What is the implication of these, given the
experimental design?

• In the experimental condition,
• you need to hold memory items in your short-term
  memory while answering the verification
  questions.
• In the control condition,
• you dont need to store memory items while
  answering the verification questions.

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Dependent Measure

• Accuracy/response time for the verification task
• What results would you expect if Baddeleys
  hypothesis is correct?
• Hint (computer metaphor).
• If you open lots of programs in your computer,
  what happens?

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So what?
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• RAM is filled with lots of information.
• E.g., Excel, Words, Photoshop, Netscape, Eudora,
  .
• Each operation gets very cumbersome (slow).

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Baddeleys hypothesis

• If short-term memory is something to do with
  temporary manipulation of information (solving
  math problems, reasoning, etc.),
• Then performance for the verification task should
  decline in the experimental condition, as
  compared to the controlled condition.

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Results

• Control condition vs. Experimental condition
• Subjects in the Experimental condition were less
  accurate than subjects in the Control condition.
• They also required longer time to make decision.
• Mean reasoning time
• Control ? 2.73 sec
• Experimental ? 4.75 sec
• Similar results were found in other tasks
• Sentence comprehension, grammar judgment, and
  problem solving tasks.

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Interpretations

• Why longer response time required in the
  experimental condition?
• The experimental condition and the control
  condition differed only in one aspect.
• The verification task was given while carrying
  out the memory task.
• The short-term memory task and the sentence
  verification task required the same temporary
  storage (buffer) space.

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Working memory

• Short-term memory is working memory.
• It is a temporary storage for manipulating
  information.
• Working memory is required to perform many
  cognitive tasks (reasoning, problem solving,
  language comprehension, etc.).

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Encoding format of working memory

• What is the encoding format of working memory?
• the encoding format of short-term memory.
• Auditory (verbal ) encoding
• Conrands confusion matrix.
• auditory rehearsing sends information stored in
  working memory to long-term storage.

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Demonstration
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Task 1

• Find the answer to the following question as
  quickly and accurately as possible.

Lucy came before Jane. Kathy arrived after Jane.
Suzy came before Lucy. Who came first? Who
came second?
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Task 2

• Find the answer to the following question as
  quickly and accurately as possible. While you
  are looking for the question, please keep saying
  the-the-the-the.

Tom arrived after Steve. John came before Steve.
Mike arrived before John. Who came first? Who
came second?
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Verbalization hampers the task performance

• Why?
• Because the capacity of working memory is
  limited.
• The verbalization (the-the-the-) left little
  room for the sentence verification task.

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Working memory (Baddeley, 1986, 1992)

• Working memory consists of 3 components
• Central executive, phonological loop,
  visuospatial sketchpad
• Phonological loop
• Hold acoustic information (verbal rehearsal)
• (sound card?)
• Visuospatial sketchpad
• Hold visual and spatial information
• E.g., mental rotation
• Central executive
• Allocate attention, coordinate subsytems

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Working memory

• Working memory is related to many cognitive
  activities.
• reading comprehension, solving problems,
  acquiring new vocabulary...

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Working memory and learning new words in children

• Gathercole and Baddeley (1989)
• Subjects
• Children (4-5yrs old)
• Test1
• measure their cognitive abilities
• general intelligence, reading ability, non-verbal
  cognitive skills

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• Test 2 (non-word repetition task)
• the experimenter read aloud non-word syllables
  (e.g., mashpole, woop kintent. ) to
  children. Then, children were asked to repeat
  the syllables.
• Childrens ability to repeat the syllables was
  scored.

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• Test 3
• 1 yr later, the experimenter measured childrens
  vocabulary score (majoring roughly the number of
  new words these children acquired in a year).

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• Results
• childrens verbalization ability (as measured by
  their ability to repeat non-word syllables)
  correlated with their vocabulary acquisition
  score.
• ---gt
• childrens verbalization ability is related to
  their ability to acquire new words.