Transcript Short – term memory & Working memory

Sensory memory &
Short – term memory
Part I
พ.ญ. กาญจนา พิทกั ษ์วฒั นานนท์
อายุรแพทย์เฉพาะทางระบบประสาทสมอง
1
What is memory ?
• Processes involved retaining, retrieving,
using information
• Original information is no longer present
ความทรงจา ( memory ) คือ
ขบวนการทางานของสมองที่เกี่ยวข้องกับการเก็บบันทึกจดจาข้อมูลที่เรี ยนรู ้ใหม่ๆ
การระลึกนึกถึงข้อมูลที่เคยเก็บไว้ หรื อการดึงข้อมูลดังกล่าวมาใช้ในกระบวนการ
คิดและการทางานต่างๆของสมอง ซึ่ งข้อมูลต่างๆเหล่านี้อาจเกี่ยวกับสิ่ งเร้าทัว่ ไป
อาจเป็ นภาพ เป็ นเหตุการณ์ เป็ นแนวคิด หรื อทักษะความชานาญในด้านต่างๆที่
สมองเคยรับรู ้เรี ยนรู ้และมีประสบการณ์มาก่อน โดยสิ่ งต่างๆเหล่านี้ลว้ นแล้วแต่
เป็ นสิ่ งที่เกิดขึ้นในอดีต ไม่ใช่สิ่งที่เกิดขึ้นอยูใ่ นช่วงขณะนั้น
2
Memory
• Time machine (mental time travel)
– To go back just a moment
• To the words you read at the beginning of the
sentence
– To go back many years
• To events as early as a childhood birthday party
3
Memory
• Time machine : Mental time travel
– Place you back in situation
– Remember what we need to do later
– Remember facts we have learned
– Use skills we have acquired
– Day-to-day activities
4
Memory
ความทรงจาของสมองเปรี ยบเหมือนเครื่ องมือบันทึกข้อมูลสาหรับย้อนเวลาของสมอง ( time
machine ) ทาให้สมองมีความสามารถในการย้อนกลับไปนึกถึงสิ่ งที่เพิ่งจะเกิดขึ้นชัว่ ครู่
จนถึงสามารถย้อนกลับไปนึกถึงเหตุการณ์ในอดีตที่ผา่ นไปแล้วหลายสิ บปี ได้
การเดินทางย้อนเวลากลับไปสู่ขอ้ มูลในความทรงจาของสมอง ( mental time travel )
ทาให้รู้สึกเหมือนเดินทางกลับไปอยูใ่ นสถานการณ์ที่มีประสบการณ์ในอดีต มีท้งั ความรู ้สึกนึก
คิดต่างๆที่เคยเกิดขึ้นและรายละเอียดของเหตุการณ์ที่เคยได้รับรู ้ จนบางครั้งเหมือนกับเหตุการณ์
นั้นกาลังเกิดขึ้นอยูอ่ ีกครั้ง ( re experiencing )
นอกจากความทรงจาของสมองจะมีประโยชน์ต่อการระลึกหรื อจดจาเหตุการณ์ที่ผา่ นมาในอดีตแล้ว
ยังมีความสาคัญอย่างมากต่อการใช้ชีวติ ประจาวันอีกด้วย ไม่วา่ จะเป็ นการจดจาสิ่ งที่จะต้องทาใน
แต่ละวัน หรื อแม้แต่กิจวัตรประจาวันเช่นการอาบน้ าแปรงฟันแต่งตัวก็ยงั ต้องใช้ความสามารถ
ด้านความทรงจาของสมองที่ทาให้เกิดการเรี ยนรู ้และความชานาญในการทากิจกรรมต่างๆด้วย
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Create a “Top 10 list” of :
What you use memory for ?
Student top
5 items :
1. Material for exams
2.
3.
4.
5.
Their daily schedule
Names
Phone numbers
Directions to places
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Top 10 list of purposes
what you use memory for…
Answer : Differ from the ones to the others
– Student
– Construction worker
– Homemaker
: material for exams
: framing a house
: cleaning the house
– Business executive
– Politicians
: ???
: ???
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Top 10 list of purposes
what you use memory for…
• Most : Day-to-day activities
– Labeling familiar objects : “ Book ” is ??
– Having conversations : talking , Q & A
– Knowing what to do in restaurant : paying check
– Finding the way to somewhere : map
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How important of memory..
• When people lose their memory..
• What happens to people’s lives..
For example : Clive Wearing
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Clive Wearing
• Musician & choral director in England
• Viral encephalitis : destroyed temporal lobe
• Cannot forming new memories ( LTM )
– Remember what just happen
– Then forget everything else
• Problem : he react like 1st meet when he
meet someone in a few minutes again
10
Clive Wearing’s diary
• He has no memory of ever writing
anything except for the sentence he has
just written
• He is confused
– He record events in his handwriting
– He has no memory for writing events
– He denies that events are his
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Important of memory
• Wearing lives totally within a few minutes
• He describes his life as being “like death”
• He has no ability to have normal life
• He cannot participate in life in any
meaningful way
• He need to
for by others
be constantly cared
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Chapter summery 1
• Memory is the process involved in retaining,
retrieving, and using information about stimuli,
images, events, ideas, and skills after the
original information is no longer present.
• It is important for dealing with day-to-day events,
and cases such as Clive Wearing’s illustrate the
importance of memory for normal functioning.
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basic principles of memory :
The modal model of memory
– Richard Atkinson & Richard Shiffrin’ s : 1968
– Proposed 40 years ago
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Stages of modal model
• Called structural features of the model
• There are 3 major structural features
– Sensory memory
– Short-term memory
– Long-term memory
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Structural features
1 sensory memory
– Initial stage
– Holds all incoming information for seconds or
fractions of a second
2 short-term memory : STM
– Holds 5-7 items for about 15-20 seconds.
3 long-term memory : LTM
– Hold a large amount of information for years
or even decades.
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Control processes
• Active processes that can be controlled by
the person and may differ from one task to
another.
• For example :
Rehearsal , Attention , Relating
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Rehearsal
• Repeating a stimulus over and over
• You might repeat a telephone number in
order to hold it in your mind after looking it
up in the phone book.
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Attention
• You selectively focus on other information
you want to remember
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Relating
• Relating the numbers in a phone number
to a familiar date in history
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Phone number for Mineo’s
Pizza
• Rachel looks up the number in a phone book
– All of the information that enters her eyes is
registered in sensory memory.
• Rachel focuses on the number for Mineo’s
pizza using the control process of selective
attention, so the number enters STM
– Rachel uses the control process of rehearsal to
keep it there
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Phone number for Mineo’s
Pizza
• After Rachel has dialed the phone number
– She may forget it because it has not been
transferred into long-term memory.
• She decides to memorize the number so
next time she won’t have to look it up in
the phone book.
– Transfers the number into LTM
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Phone number for Mineo’s
Pizza
• A few days later,
• When Rachel’s urge for pizza returns, she
remembers the number.
• The information must be retrieved from
LTM so it can reenter STM to be used.
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Chapter summery 2
• Atkinson and Shiffrin’s modal model of
memory consists of three structural
features – sensory memory, short-term
memory, and long-term memory.
• Another feature of the model is control
process such as rehearsal and attentional
strategies.
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Sensory memory
• Sensory memory is the retention,
– for brief periods of time,
– of the effects of sensory stimulation.
• Example : Brief retention for the effects of
visual stimulation
– The trail left by a moving sparkler
– The experience of seeing a film
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The sparkler’s trial
• A sparkler can cause a trail of light when it
moved rapidly.
• The lighted trail is a creation of your mind, which
retains a perception of the sparkler’s light for a
fraction of a second.
• This retention of the perception of light in your
mind is called the persistence of vision.
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Projector’s shutter
A person viewing the film
• sees the progression of still images as
movement
• doesn’t see the dark intervals between the
images because the persistence of vision
fills in the darkness by retaining the image of
previous frame.
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Flickers of film
• The period between the images is too long
(more than 24 times/sec.)
• Longer dark interval
• The mind can’t fill in the darkness
completely
• A person perceive a flickering effect
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Sperling’s experiment :
Measuring the visual icon
• Icon = image
• An array of letters (12 icon in matrix)
XMLT
AFNB
CDZP
• Flashed on the screen for 50 ms.
– 50 ms = 50/1000 sec.
• Asked participants to report a whole
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Sperling’s experiment :
Measuring the visual icon
The whole report method
• They were able to report an average of 4.5
out of the 12 letters
– Concluded ??? : the exposure was brief,
participants saw only an average of 4.5 of the
12 letters
– Perhaps ??? : participants saw most of the
letters immediately, but their perception faded
rapidly
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Sperling’s experiment :
Measuring the visual icon
Determine which of 2 possibilities is correct
• Partial report method
– Flashed the matrix for 50 ms
– Immediately after it was flashed (turned off)
– Sounded one of the following cues tones
• High pitched : top row
• Medium-pitched : middle row
• Low-pitched : bottom row
– To indicate which row of letters the
participants were to report
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Sperling’s experiment :
Measuring the visual icon
Partial report method
• Sound after flashed off
– Actual letters were no longer present
– Participant’s attention was directed not to the
actual letters
– Participant’s attention was directed to
whatever trace remained in their mind
– Cues tones directed participants to focus their
attention onto one of the rows
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Sperling’s experiment :
Measuring the visual icon
Partial report method
• Result : they correctly reported an average
of about 3.3 of the 4 letters (82 %)
• Conclude : they saw 82% of letters
They were not able to report all of these
letters because they rapidly faded as the
initial letters were being reported
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Sperling’s experiment :
Measuring the visual icon
To determine the time course of this fading
• Delayed partial report method
– The presentation of cue tones was delayed
for a fraction of a second after the letters were
extinguished
– Result : delayed for ½ second  report only
slightly more than 1 letter in a row
– Result : same number of whole report method
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Sperling’s experiment
• Immediately after flashed off
– All or most (82%) of stimulus is available for
perception
– This is sensory memory
– Sensory memory registers all or most of the
information that hits our visual receptors
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Sperling’s experiment
• Over the next second after flashed off
– Sensory memory fades
– Information decays within less than second
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Sperling’s experiment
• A short-lived sensory memory registers all
or most of the information that hits our
visual receptors
– Capacity of sensory memory = large
• but that this information decays within less
than a second.
– Duration of sensory memory = brief
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Duration of sensory memory
• Sensory memory for visual stimuli
– Iconic memory = visual icon
– Persistence of vision
– Duration less than one second
• Sensory memory for auditory stimuli
– Echoic memory
– Persistence of sound
– Duration lasts for a few second
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Important of sensory memory
• Collecting information to be processed
• Holding the information briefly while initial
processing is going on
• Filling in the blanks when stimulation is
intermittent
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Chapter summery 3
• Sperling used two methods, whole report
and partial report, to determine the
capacity and time course of visual sensory
memory.
• The duration of visual sensory memory
(iconic memory) is less than 1 second,
• The duration of auditory sensory memory
(echoic memory) is about 2-4 seconds.
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Short-term memory
• Brief duration
– What is the duration of STM ?
• Most of information is lost
– How much information can STM hold ?
• Some of information store to be long-term
memory
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Short-term memory
• Whatever you are thinking about right
now, or remember from what you just
read, is in your STM
• How do we understand this sentence ?
“The human brain is involved in everything we
know about the important things in life, like
music and dancing”
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What is duration of STM ?
• John Brown , Lloyd Peterson , Margaret
Peterson : experiments to determine the
duration of STM
• Remembering three letters
– Tell the person that you are going to read three letters followed
by a number
– Once the person hears the number he should start counting
backward by 3’s from that number
– When say Recall : write down the three letters heard at the
beginning
– Once the person start counting,
– time 20 seconds and say “Recall”
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Remembering 3 letters
• Peterson and Peterson’s results
3-second delay : 80 % remember of letters
18-second delay : 10 % remember of letters
• Participants forgot the letters because
their memory trace decayed during the 18
seconds
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Remembering 3 letters
• Peterson’s results  performance
average over many trials
• G. Keppel and Benton Underwood (1962)
– Re-analysis Peterson’s results
– Re-analysis  compared 1st & 3rd trial
performance
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Remembering 3 letters
• G. Keppel and Benton Underwood
– First trial : a little falloff
– Third trial : seeing a drop-off
• Why would memory become worse after a
few trial ?
– The drop-off in memory was due to proactive
interference (PI) = interference that occurs when
information that was learned previously interferes with
learning new information
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Proactive interference
• What might happen when Rachel calls the
number she had memorized for Mineo’s
Pizza (521-5100) changed to 522-4100
Rachel tries to remember the new number
• She make mistakes at first
• PI is causing her memory for the old
number to interfere with her memory for
the new number
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Proactive interference
• Old number : 521-5100
• New number : 522-4100
• New number is similar to the old one
– Old number adds to the interference
– Old number makes it harder to remember the
new number
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Proactive interference (PI)
• PI is a basic mechanism of forgetting
• PI is about 15 – 20 sec.
• PI  Rehearsal is prevented
 outcome of PI
= effective duration of STM
 decreased
57
Chapter summery 4
• Short-term memory is our window on the
present.
– Brown, and Peterson, determined that the
duration of STM is about 15-20 seconds.
• They interpreted the short duration of STM
as being caused by decay, but a later
reanalysis of their data indicated it was
due to proactive interference.
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What is the capacity of STM ?
• The information is not only lost rapidly
from STM, but there is a limit to how much
information can be held there.
• This capacity can be measured by Digit
span ( the number of digits a person can
remember ).
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Coglab : Digit span
• Using an index card or piece of paper,
cover all of the numbers below
2
3
6
7
8
4
5
1
9
4
3
4
8
8
4
6
9
8
2
2
5
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7
2
6
3
2
8
8
0
1
9
9
4
1
4
2
8
5
32
807
1 6 3 7 60
Coglab : Digit span
• Move the card down to uncover the first
string of numbers.
2
3
6
7
8
4
5
1
9
4
3
4
8
8
4
6
9
8
2
2
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7
2
6
3
2
8
8
0
1
9
9
4
1
4
2
8
5
32
807
1 6 3 7 61
Coglab : Digit span
• Read the numbers , cover them up, and
then write them down in the correct order.
2
3
6
7
8
4
5
1
9
4
3
4
8
8
4
6
9
8
2
2
5
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7
2
6
3
2
8
8
0
1
9
9
4
1
4
2
8
5
32
807
1 6 3 7 62
Coglab : Digit span
• Then move the card to the next string and
repeat this procedure until you begin
making errors.
2149
39678
649784
7382015
84261432
482392807
5 8 5 2 9 8 1 6 3 7 63
Coglab : Digit span
• The longest string you are able to
reproduce without error is your digit span.
• The typical span is
between 5 and 8
2
3
6
7
8
4
5
1
9
4
3
4
8
8
4
6
9
8
2
2
5
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7
2
6
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0
1
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1
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2
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5
32
807
1 6 3 7 64
What is the capacity of STM ?
This capacity can be measured by Digit
span ( the number of digits a person can
remember )
• The typical span is between 5 and 8 digits
• According to measurements of digit span,
the capacity of STM is 5 – 8 items.
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The magic number seven
plus or minus two
• George Miller (1956) : chunking concept
• The famous paper titled : “ The magic
number seven, plus or minus two ”
• Explain : How we remember words and
combinations of words ?
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How we remember words and
combinations of words
• Trying to remember the following words
– Monkey
– Child
– Wildly
– Zoo
– Jumped
– City
– Ringtail
– Young
67
How we remember words and
combinations of words
• How to remember :
– How many units are there in this list ?
• 8 words : 4 pairs
»
»
»
»
Ringtail monkey
Jumped wildly
Young child
City zoo
– We can take this one step further by arranging
these groups of words into one sentence.
» The ringtail monkey jumped wildly for the young child at
the city zoo.
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How we remember words and
combinations of words
• Is the sentence about the child watching a
monkey at the zoo 8 items, 4 items or 1
item ?
• Small units (like words) can be combined
into larger meaningful units (like phrases),
or even larger units (like sentences,
paragraphs, stories)
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Concept of chunking
• Chunk : a collection of elements that are
strongly associated with one another but
are weakly associated with elements in
other chunks
– Ringtail
• Associated with : monkey
• Not ass. with : child , jumped
The ringtail monkey jumped wildly for the young child at the city zoo
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Concept of chunking
• We can recall a sequence of 5 – 8 words
• Chunking increase the memory span to 20
words or more
• Meaning can increase our ability to hold
information in STM
71
K. Anders Ericcson and coworkers
(1980)
• S.F. participant : typical 7 digits span
• After extensive training : 79 digits span
• How did he do it ?
– 3492 : 3 min and 49.2 sec , near world record mile time
– 893 : 89.3 , very old man
• S.F. was a runner used memory stored in
LTM about runner times
• S.F. used a chunk to remember best
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Concept of chunking
• William Chase & Herbert Simon
– They showed chess players pictures of chess
pieces on a chessboard for 5 sec
– Then asked to produce the positions they had
seen
– Results compared : chess master & beginner
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Concept of chunking
• William Chase & Herbert Simon
Actual game positions
• Chess master : correct 16 / 24 ( 1st try )
• Beginner
: correct 4 / 24 ( 1st try )
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Concept of chunking
• William Chase & Herbert Simon
Actual game positions
• Chess master : correct 24 / 24 ( 4th try )
• Beginner
: still incorrect ( 7th try )
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Concept of chunking
• William Chase & Herbert Simon
Random positions
• Chess master : 3 / 24
• Beginner
: 3 / 24
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Concept of chunking
Actual game positions : master superiorly
His ability to group the chess pieces into meaningful
chunks
Used interaction between STM & LTM
Random positions
: master vanished
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Concept of chunking
• Chunking is an essential feature of STM
because it expands the capacity of STM
so it can handle 5-8 chunks rather than
just 5-8 items
• This enables the limited-capacity STM to
deal with the large amount of information
involved in many of tasks we perform
everyday ( chunking letters into words as you read )
79
Chapter summery 5
• The capacity of STM is 5-8 items, as
measured by digit span.
– This capacity can be expanded by chunking,
so that it is possible to remember 5-8 chunks
rather than 5-8 digits.
• Examples of chunking are the memory
performance of the runner S.F. and how
chess masters use their knowledge of
chess to remember chess piece positions.
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How is information coded in STM ?
• Coding : the way information is represented
• Physiological approach to coding : How a
stimuli is represented by the firing of a number of
neurons
• Mental approach to coding : How a stimuli or
an experience is represented in the mind
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Physiological approach to coding :
Distributed code
•
•
•
•
•
Bill
Samantha
Roger
Grace
Ellen
•
•
•
•
•
1>2>3
1<<2>3
1<2<3
1<2>>3
1>>2<<3
Groups of neurons firing : different pattern
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Mental approach to coding
After you have just finished listening lecture
• Some of ways you might remember what
happened in class
– Remembering the sound of your professor’s
voice
– Imagining what your professor looks like
– Remembering what your professor was talking
about
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Auditory coding
• R. Conrad 1964
• Participants saw a number of target letters flashed
briefly on a screen
• Participants were told to write down the letters in
the order they were presented
• Finding : when participants made errors,
they were most likely to misidentify the
target letter as another letter that sound
like the target ( F  S , X )
87
Auditory coding
• Conrad concluded :
Code for STM is auditory
( based on the sound of stimulus ),
rather than visual
( based on the visual appearance of the stimulus )
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Visual coding : examples
• Remembering the details of a diagram or
an architectural floor plan, require visual
codes
• Radicals & Characters in Chinese
language
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Visual coding
• Guojun Zhang and Herbert Simon 1985
• Presented Chinese language symbols to nativespeaking Chinese participants
• Stimuli : Radicals , Characters
– Radicals : symbols that are part of Chinese
language & that are not associated with any
sound
– Characters : consist of a radical plus another
symbol & do have sound
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Visual coding
• Participants were asked to reproduced a
series of Characters
• They were able to reproduce a string of
2.7 radicals : recall based on visual coding
• They were able to reproduced a string of
6.4 characters : greater recall when
auditory coding
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Visual coding / Auditory coding
• Both involved in STM
• Superior memory for Characters from :
• Characters  has sound / auditory coding
• Radicals  no sound , no meaning / visual coding
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Semantic coding
• Delos Wickens and coworkers 1976
• 3 different groups of participants :
• A professions group
• A meat group
• A fruit group
• Each group listened to 3 words, counted
backward for 15 sec, then attempted to recall 3
words
• Repeated 4 trial, different words in each trial
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Wickens’ experiment : result
• Trial 2 & 3 : decrease in due to build up PI
( Proactive Interference )
• Trial 4 same category : remain low for fruit
group
• Trial 4 switch category : release from PI in
Profession & Meat groups  improved
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Wickens’ experiment : concluded
• The release from PI depends on the
words’ categories ( fruit, meat, profession )
• Different categories : different meaning
• This results demonstrate the operation of
semantic coding in STM
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Chapter summery 6
• Information can be coded in STM in terms
of sound (auditory coding), vision (visual
coding), and meaning (semantic coding).
– Auditory coding was illustrated by Conrad’s
experiment that analyzed the type of errors
made in memory for letters.
– Visual coding was illustrated by Zhang and
Simon’s experiment with Chinese characters,
– semantic coding by Wickens’ release from
proactive interference experiment
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Working memory
พญ. กาญจนา พิทกั ษ์วฒั นานนท์
100
Working memory
• Alan Baddeley and Graham Hitch 1974
• The modern model of memory
• STM be replaced by working memory
• Working memory : a mechanism that
consists of a number of specialized
components
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Working memory
• Reading text & Remember numbers
• Keep these numbers in your mind ( 7 1 4 9 ) as
you read the following passage :
» Baddeley reasoned that if STM had a limited storage
capacity of about the length of a telephone number,
filling up the storage capacity should make it difficult
to do other tasks that depend on STM. But he found
that participants could hold a short string of numbers
in their memory while carrying out another task, such
as reading or even solving a simple word problem.
How are you doing with this task? What are the
numbers ? What is the gist of what you just read?
102
Working memory
• Reading text & Remember numbers
– How are you doing with this task ?
– What are the numbers ?
– What is the gist of what you just read ?
103
Working memory
• Reading text & Remember numbers
• Baddeley’ s participants were able to read
while simultaneously remembering
numbers
• Digit span task : handled by one component
• Comprehending the paragraph : handled by the
others
• Concluded : the short term process must
consist of a number of components that
can function separately
104
Working memory
• Baddeley decided the name of the short
term process should be changed from
STM to working memory
• Working memory : a limited-capacity
system for temporary storage and
manipulation of information for complex
tasks such as comprehension, learning,
reasoning
105
Working memory
• Working memory differs from STM
• STM is a single component,
– whereas working memory consists of a number of parts
• STM is with holding information for a brief period of
time,
– whereas working memory is concerned with the
manipulation of information that occurs during complex
cognition
» Problem solving
» Thinking
» Attention
106
» language
Chapter summery 7
• The short-term memory component of the
modal model was revised by Baddeley in
order to deal with results that couldn’t be
explained by a single short-term process.
• In this new model, working memory
replaces STM
107
Atkinson and Shiffrin’s model of memory
108
109
Working memory
• Manipulation of information through the
action of 3 components :
• Phonological loop : verbal & auditory information
• Visuospatial sketch pad : visual & spatial information
• Central executive
110
Phonological loop
• Holds verbal and auditory information
• Example :
• When you try to remember a telephone number or
a person’s name
• Try to understand what your professor is talking
about
111
Visuospatial sketch patch
• Holds visual & spatial information
• Example :
• When you form a picture in your mind
• To do a tasks like solving a puzzle
• Finding your way around campus
112
113
Central executive
• Central executive pulls information from LTM
• Central executive coordinates the activity of the
phonological loop and visuospatial sketch patch
by
– focusing on specific parts of a task
– switching attention from one part to another
• Central executive is where the major work of
working memory occurs
114
Central executive
To decide how to divide attention between
different tasks
Imaging you are driving in a strange city
The news is broadcast on the car radio
A friend in the passenger seat is reading you
directions to a restaurant
– phonological loop : verbal direction
– sketch pad : visualized a map of streets
• Central executive : coordinating & combining both
• Central executive : ignore the car radio
115
116
Chapter summery 8
• Working memory is a limited-capacity system for
storage and manipulation of information in
complex tasks.
• It consists of three components
– the phonological loop, which holds auditory or verbal
information,
– the visuospatial sketch pad, which holds visual and
spatial information,
– the central executive, which coordinates the action of
the phonological loop and visuospatial sketch pad.
117
Phonological loop
• Phenomena support the idea of a system
specialized for language
• The phonological similarity
• The word - length effect
• Articulatory suppression
118
Phonological similarity effect
• Conrad’s experiment : showed that people
often confuse similar-sounding letters
• T,P
• F,X,S
• Result : Auditory coding in STM
• Words are processed in the phonological
loop of working memory
119
Phonological similarity effect
• Task 1 : Slowly read the following letters.
Look away and count to 15. Then write
them down.
g c b t v p
• Task 2 : Now do the same thing for these
letters.
f l k s y g
120
Phonological similarity effect
• Which of the two tasks was more difficult?
• Task 1 : more difficult
• Task 1 : similar-sounding letters
• People confuse the similar – sounding
letters and report letters that weren’t
present ( d e z )
121
Phonological similarity effect
• occurs when letters or words
that sound similar are
confused
122
Word-Length effect
• Task 1 : Read the following words, look
away, and then write down the words you
remember.
beast, bronze, wife, golf, inn, limb, dirt, star
• Task 2 : Now do the same thing for the
following list.
alcohol, property, amplifier, officer, gallery, mosquito,
orchestra, bricklayer
123
Word-Length effect
• Which of the 2 tasks was more difficult ?
• Task 2 : more difficult
• Task 2 : the words more longer
• Longer words takes longer …..
– to rehearse the long words
– to produce them during recall
124
Word-Length effect
• occurs when memory ( for
lists of words ) is better for
short words than for long
words
125
Word-Length effect
• English numbers
: one two three four five six …
• Welsh numbers
: un dau tri pedwar pump chwech …
• English more shorter & easier than Welsh
• American children have a larger digit span
than Welsh children
126
Word-Length effect
• People are able to remember the number
of items that they can pronounce in about
1.5 – 2.0 sec
• Try to counting out loud, as fast as you
can, for 2 sec
• The number of words you can say should
be close to your digit span
127
Articulatory suppression
• Task 1 : Read following list. Then turn away and
recall as many words as you can.
• Dishwasher, hummingbird, engineering, hospital,
homelessness, reasoning
• Task 2 : Read the following list while repeating
the word “the” out loud. Then turn away and
recall as many words as you can.
• Automobile, apartment, basketball, mathematics, syllogism,
Catholicism
128
Articulatory suppression
• Which of the 2 tasks was more difficult ?
• Task 2 : harder
• Task 2 : repeating the, the, the,… overloads the
phonological loop.
• The, the, the,….reduces the ability to
remember lists of words
129
Articulatory suppression
occurs when a person is prevented
from rehearsing items to be
remembered by repeating an
irrelevant sound
such as “ the ”
( the, the, the, … )
130
Articulatory suppression
• Eliminates the word-length effect
: short word leave more space for
rehearsal
The, the, the,… eliminates this
rehearsal advantage for short words
131
132
133
Articulatory suppression
• Reduces the phonological similarity effect
: reading initially represented in the visuospatial
sketch pad,
and then transferred to the phonological loop
The phonological loop is engaged by the, the,
the,…
134
135
Articulatory suppression
•
Articulatory suppression has 3 effects :
1.
it reduces the memory span : speaking interferes
with rehearsal
2.
it eliminates the word-length effect
3.
it reduces the phonological similarity effect for
reading words
136
Chapter summery 9
• The following effects can be explained in
terms of operation of the phonological
loop:
– (a) phonological similarity effect
– (b) word-length effect
– (c) articulatory suppression
137
Visuospatial sketch pad
• Lee Brooks experiments 1968
Holding a verbal stimulus in the mind
– Task 1 : memorize the sentence below, and
then without looking at it, consider each word
in order and say “yes” if it is a noun and “no” if
it isn’t a noun
John ran to the store to buy some oranges
138
Visuospatial sketch pad
Holding a verbal stimulus in the mind
– Task 2 : memorize the sentence below, and
then use fig. 5.18 to indicate whether each
word in the order it appears in the sentence,
point to the “Y” if the word is a noun and to
the “N” if it isn’t ( move down a row in the
display in fig. 5.18 for each new word )
The bird flew out the window to the tree
139
140
Visuospatial sketch pad
Holding a verbal stimulus in the mind
• Which of the 2 tasks was more difficult ?
– Task 1 : said Yes or No  more difficult
• Task 1 : stimulus & task  verbal  overload
phonological loop
– Task 2 : stimulus  verbal , task  spatial
• Task 2 : the processing was distributed between
the loop and sketch pad  task 2 : easier
141
Visuospatial sketch pad
Holding a verbal stimulus in the mind
Holding the sentence : verbal task
Saying “yes” or “no” : verbal task
Pointing to “Y” or “N” : spatial task
Task 1 : overloading phonological loop
Task 2 : distributing processing across both
142
Visuospatial sketch pad
Holding a spatial stimulus in the mind
Task 3 : visualize the F in fig. 5.20.
then look away from the figure,
and while visualizing the F in your mind,
start at the upper left corner ( the one marked
with the * )
143
144
Visuospatial sketch pad
Holding a spatial stimulus in the mind
Task 3 :
visualizing the F in your mind,
start at the upper left corner ( the one marked
with the * )
moving around the outline of the F in a
clockwise direction in your mind,
point to Y in fig. 5.18 for an outside corner,
and N for an inside corner
145
Visuospatial sketch pad
Holding a spatial stimulus in the mind
YY
YN
146
Visuospatial sketch pad
Holding a spatial stimulus in the mind
task 4 : visualize the F again,
but this time, as you move around the
outline of the F in a clockwise direction in
your mind,
say “yes” if the corner is an outside
corner ( like the first one )
or “no” if it is an inside corner
147
Visuospatial sketch pad
Holding a spatial stimulus in the mind
Which was easier, pointing to “Y” or “N”
or saying “yes” or “no” ?
saying “yes”
or “no” is easier
148
149
Visuospatial sketch pad
Holding a spatial stimulus in the mind
Holding the F in the mind : spatial task
Saying “yes” or “no” : verbal task
Pointing to “Y” or “N” : spatial task
Task 3 : overloading to spatial task
Task 4 : distributing processing across both
150
Chapter summery 10
• Brooks did some experiments that
indicated that two tasks can be handled
simultaneously if one involves the
visuospatial sketch pad and the other
involves the phonological loop.
• Performance decreases if one component
of working memory is called on to deal
with two tasks simultaneously.
151
Central executive
Does most of the work of working memory
• Coordinates the operation of the
phonological loop & visuospatial sketch
pad
• Paying attention to relevant information
• Controlling the suppression of irrelevant
information
152
153
Central executive
Coordinate :
phonological loop + visuospatial sketch pad
– Listening to the friend guiding the way
– Looking for street when driving a car
154
Central executive
Suppresses irrelevant information + pays
attention relevant information
– Ignore : radio sound
– Select : friend voice
155
Central Executive
Adam Gazzaley and coworkers 2005
“ face
relevant ” task
• Participants were told to remember the faces
and ignore the scenes when the four cue stimuli
( 2 faces & 2 scenes ) were presented
• After 9 second delay
• Indicate whether the face presented during the
test period matched one of the cue faces
156
Central Executive
Adam Gazzaley and coworkers 2005
“passive” task
• Participants just looked at the pictures
• and pressed a button indicating the
direction of the arrow during the test
157
158
Central Executive
Adam Gazzaley and coworkers 2005
• Measured the fMRI response of an area in
the temporal cortex that responed to
scenes
• Measured how accurately participants
were able to indicate whether the test face
matched the cue faces
159
Central Executive
Adam Gazzaley and coworkers 2005
Results : 2 groups of participants
• “good suppressors” : less brain activity
• “poor suppressors” : greater brain activity
when they were supposed to be ignoring
the scenes than during the passive
condition
160
161
Central Executive
Adam Gazzaley and coworkers 2005
• Good suppressors : 89 % correctly
• Poor suppressors : 67 % correctly
• Concluded : the ability to suppress
irrelevant information, which is a central
executive function, results in better
memory for relevant information
162
Chapter summery 11
• Researchers are just beginning to understand
the functioning of the central executive.
– One function, the suppression of irrelevant
information, was studied by Gazzaley by measuring
brain activity and memory performance during a
memory task that involved suppression.
• The results of this experiment showed that
greater suppression, measured by brain activity,
was associated with better performance in the
memory task.
163
Update on model
STM (Atkinson, Shiffrin)  working memory
(Baddeley)
• Can’t explain some results
– The,the,the,….  decrease in memory span ( but
only slightly 7  5 )
– Should decrease more than this results
164
Baddeley’s
revised working memory model
• Added : episodic
buffer
• Models designed to explain mental
functioning are constantly being refined
and modified to explain new results
165
166
Episodic buffer
• Episodic buffer is basically a “backup”
store that communicates with both LTM
and the components of working memory
– It can hold information longer
– It has greater capacity
than phonological loop or spatial sketch pad
167
Chapter summery 12
• The working memory model has been
updated to include an additional
component called the episodic buffer,
which has a greater capacity and can hold
information longer than the phonological
loop or visuospatial sketch pad.
168
169
Working memory & Brain
• Prefrontal cortex ( PF ) : Working memory
– Receives input from the sensory areas (
processing incoming visual & auditory
information )
– Receives signals from areas involved in
carrying out actions
– Is connected to areas in the temporal cortex
that are important for forming LTM
170
Prefrontal cortex : working M.
171
Delayed-response task
Experiment in monkey
• Task :
– Monkey  hold information in working
memory
• Delay period :
– Retrieve information in working memory
172
173
Delayed-response task
• Task :
– Monkey sees a food reward in one of two food wells
– Both wells are then covered
– A screen is lowered
Delay
– Screen is raised again
– Monkey reach a food wells
• Correct  obtain a reward
• Incorrect  no reward
174
Working memory & Brain
delayed-response task in trained-monkeys
Observe
Delay
Correct : reward
175
Working memory & Brain
in prefrontal cortex damaged-monkeys
Removed prefrontal cortex  correct by change
176
Chapter summery 13
• Behaviors that depend on working
memory can be disrupted by damage to
the prefrontal cortex.
• This has been demonstrated by testing
monkeys on the delayed response task.
177
Working memory & Brain
• Prefrontal cortex : damage / removed
– Infants younger than 8 months : not develop
– Out of sight , Out of mind
178
Neuron that hold information
• Shintaro Funahashi and coworkers 1989
Recorded from neurons in a monkey’s PF
• Delayed-response task
x
--ll----------------
x
-------llllllllllllllllll- ---------------ll--179
Shintaro Funahashi
& coworkers 1989
• Recorded from neurons in a monkey’s
prefrontal cortex
– While it carried out a delayed-response task
• To confirm :
prefrontal cortex / working memory
– Memory
• Hold information after the original stimulus is no
longer present
180
Neuron that hold information
• Monkey first looked at a fixation point : X
• Square was flashed  then off
• After delay : off fixation X
x
--ll----------------
x
-------llllllllllllllllll- ---------------ll--181
Neuron that hold information
• Shintaro Funahashi and coworkers 1989
Monkey move eyes
to where the square has been flashed
Monkey remembered the location of the square
182
Neuron that hold information
• Funahashi found neurons that responded
when the square was flashed in a
particular location and that the neurons
continued responding delay
x
--ll----------------
x
-------llllllllllllllllll- ---------------ll--183
Neuron that hold information
• The firing of these neurons indicates that an
object was presented at a particular place, and
this information remains available for as long as
these neurons continue firing
x
--ll----------------
x
-------llllllllllllllllll- ---------------ll--184
185
Neuron that hold information
Neurons from many brain areas that response during
delay in a working memory
– Primary visual cortex : receives visual signals
– Inferotemporal cortex : a visual area responsible
for perceiving complex forms
– PF prefrontal cortex : working memory
186
Chapter summery 14
• There are neurons in the prefrontal cortex
that fire to presentation of a stimulus and
continue firing as this stimulus is held in
memory.
187
Brain imaging in humans
• PET ,fMRI
Showed many area are involved in working
memory : prefrontal, frontal, parietal,
cerebellum
188
189
Chapter summery 15
• Brain imaging experiments in humans
reveal that a large number of brain areas
are involved in working memory.
190
American sign language
• Visual language
 visuospatial sketch pad
• Contain specific gestures (hand & arm)
• Used by deaf people
191
Margaret Wilson and
Karen Emmorey 1977
• Showed that
– ASL have phonological similarity effect
– ASL have word-length effects
192
Memory for lists of words
that are signed similarly
is worse than memory for
words that are signed differently
Memory is worse for words
that have signs that
take longer to produce
193
Concluded of Wilson & Emmorey
• ASL have phenomenon of phonological
loop (phonological similarity + word-length
effect)
• Phonological loop appears to process
language input regardless of whether the
language is created by sound or by
gestures
194
Finger spelling for measures memory span
Compared digit span of spoken language
195
Results of memory span from 2 studys
Blue : letter span
Gray : digit span
196
Memory span
• Spoken language : digit span
• ASL : letter span (finger spelling)
Different results from different experiment
– Different procedure, stimuli, participants
197
Wilson & Emmorey results
• No difference in letter span for speaking &
signing
• Duration & others factors are equated
• Suggest : working memory capacity for
speaking & signing is the same
198
Bavelier & coworkers results
• There is a difference in letter span for
speaking and signing
• Suggest : working memory capacity for
speaking and signing may differ in
capacity
– Perhaps due to differences between the
memory mechanisms for auditory and visual
stimuli
199
Chapter summery 16
• Comparisons of working memory for signers
who use ASL and speakers of English show that
the phonological similarity effect and wordlength effect occur for both.
• There is controversy regarding whether digit
span is different for speakers and signers, but
tests of more complex language abilities indicate
no difference between signers and speakers.
200