Long term memory & Memory errors

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Transcript Long term memory & Memory errors

Everyday memory
& Memory errors
Part I
พญ. กาญจนา พิทกั ษ์วฒั นานนท์
1
Everyday memory

memory

Is not just a “ stamp pad of experience ”

Is a place where information comes in
Is automatically stored for future reference

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Experiences become encoded

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Manipulated by a short-term process called working
memory
Admitted or not admitted to LTM
Solidified over a period of time through the process of
consolidation
Transferred back to working memory when needed
2
Memory errors

Why what we remember sometimes does not
correspond to what actually happened

Studying the errors we make when remembering
leads to the conclusion that

what we remember is determined by creative mental
processes
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This creativity is a gift that helps us determine what
happened when we have incomplete information
This creativity can affect the accuracy of our memory
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3
Chapter summery 1

To truly understand memory we need to
consider how memory operates in the
environment.

When have we do this, we find that we make
many errors in memory and that these errors
have something to tell us about the basic
mechanisms of memory.
4
Prospective memory
Remember to perform intended action

“To do” list สิ่ งที่ตอ้ งทาในวันนี้
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Going to class
Taking your books to school
Keeping an evening appointment
Taking medications
5
Prospective memory
Regular events : easier
 Brushing your teeth in the morning
Occasional events : harder
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Task of delivering a message to your friend
Ralph
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cue to remind
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Seeing Ralph later in a day
6
Prospective memory :
what I’m going to do later
Prospective memory : How to success…..
1. Remembering what you want to do
2. Remembering to do it at the right time
Giles Einstein and Mark McDaniel hypothesis
 Distinctive cues are more effective than
familiar cues
7
Cues to remind
Remembering to deliver the message to Ralph
might be harder than to stranger

Distinctive cue (unfamiliar cue)

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Stranger
Familiar cue : harder

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Ralph
Seeing Ralph might trigger associations

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Talking about the movie your saw last night
Which could distract you from remembering to deliver
the message
8
Prospective memory
Einstein and McDaniel’s experiment
 Study the effect of cue familiarity on
prospective memory
 Participants see a list of words on a computer
screen
 They should press a key when a cue word
was presented

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Familiar cues : rake , method
Unfamiliar cues : sone , monad
9
Results of Einstein and McDaniel study
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Correct responses
were three times
more likely for
unfamiliar cue words
than for familiar cue
words

Unfamiliar cues
result in better
prospective memory
10
Fig. 7-2, p. 237
Event – based task
Task is triggered when an external event occurs
Task :
 pushing a button
 Delivering a message when seeing Ralph
External event :
 presentation of the cue word
 Talking with Ralph
11
Time – based task
Task is to remember to do something at a
particular time

Your doctor tells you that you need to take a
pill every morning for the next 2 weeks
This task more difficult than event – based task
Because there is no cue
12
Time – based task
Daniel Schacter 2001
 Suggests (make it easier) : create cues that
turn time – based task into event – based
task

One way to remember to take a pill in the
morning would be to place the medication
next to your toothbrush , so when you brush
your teeth in the morning you will remember
to take a pill
13
Chapter summery 2

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Prospective memory is remembering to
perform intended actions.
Einstein and McDaniel showed that
prospective memory is better when cues for
remembering are distinctive.
Time-based prospective memory tasks are
more difficult to remember than event-based
tasks.
A solution is to turn a time-based task into an
event-based task.
14
Autobiographical memory :
what has happened in my life
Rubin 2005

Autobiographical (episodic) memory
= recollected events that belong to a
person’s past อัตถ์ชีวประวัติ


Field perspective
= you remember the event as you would see it
Observer perspective
= seeing yourself in the event
15
16
Fig. 7-3, p. 238
Autobiographical memory
Recent memory
 Field perspective > observer perspective
Remote memory
 Observer perspective > field perspective
17
Autobiographic memory

Usually considered to be episodic memories

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Episodic memories for events in our lives
Can have semantic components as well

Personal semantic memories of facts about our
lives (remember without reexperiencing events)
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Where we lived at various times
The schools we went to
The name of a childhood friend
18
Chapter summery 3

Autobiographical memory has been defined
as recollected events that belong to a
person’s past.

It can also be defined as episodic memory for
events in our lives plus personal semantic
memories of facts about our lives.
19
The multidimensional nature
of Autobiographical memory
Autobiographical memory
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Spatial component
Emotional component
Sensory component
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Damage visual area of cortex

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
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Visual memory loss (ability to recognize visualize object)
Without blindness
Loss visual retrieval cues
Loss of autobiographical memory
blind people

Auditory experience plays a role in forming autobiographical
memories
20
The multidimensional nature
of Autobiographical memory
Roberto Cabeza and coworkers 2004
 Brain – scanning study that illustrates a
difference between autobiographical memory
and laboratory memory
 Measured the brain activation caused by two
sets of stimulus photographs


A-photos : photos taken by participant
L-photos : photos taken by someone else
21
The multidimensional nature
of Autobiographical memory
Roberto Cabeza and coworkers 2004
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A-photos (Autobiographical photos)
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By 12 Duke University students digital cameras
Take pictures of 40 specified campus locations
Over a 10-day period
L-photos (Laboratory photos)
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Seen before testing (a few days later)
Unseen before testing
22
The multidimensional nature
of Autobiographical memory
Roberto Cabeza and coworkers 2004
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Testing + brain scan
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Color plate 7.2 a : parietal cortex activity
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A-photos
L-photos (seen)
L-photos (unseen)
Same response of A & L-photos
Color plate 7.2 b : hippocampal activity
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Response of A-photos more than L-photos
23
The multidimensional nature
of Autobiographical memory
Roberto Cabeza and coworkers 2004
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Response in brain
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Color plate 7.2 a

A & L-photos both activated many of the same
structures in the brain
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MTL : episodic memory
Parietal cortex : processing scenes
24
The multidimensional nature
of Autobiographical memory
Roberto Cabeza and coworkers 2004
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Response in brain
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Color plate 7.2 b
Greater A-photos activation compared to L-photos
activation in hippocampus
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A-photos
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Richness of experiencing autobiographical memories
Memories associated with taking the picture
L-photos
25
Chapter summery 4
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The multidimensional nature of autobiographical
memory has been studied by showing that people
who have lost their memory due to brain damage
experience a loss of autobiographical memory.
Also supporting the multidimensional nature of
autobiographical memory is Cabeza’s experiment,
which showed that a person’s brain is more
extensively activated when viewing photographs he
or she took him- or herself than when viewing
photographs taken by another person.
26
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27
Memory over the life span
Which particular life events we will remember
years later?
 Transition point in people’s lives
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Highly emotional events
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Graduating from college
Receiving a marriage
Surviving a car accident
Reminiscence bump
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Enhanced memory for adolescence and young
adulthood in people over 40 years old
28
Chapter summery 5

When people are asked to remember events
over their lifetime, transition points are
particularly memorable.
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Also, people over 40 tend to have good
memory for events they experienced from
adolescence to early adulthood.
This is called the reminiscence bump.
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29
30
Fig. 7-4, p. 241
Reminiscence bump
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Participants over 40 are asked to remember
events in their lives.
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Memory is high for recent events and
reminiscence bump
Why are adolescence and young adulthood
special times for encoding memories ?
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Life-narrative hypothesis
Cognitive hypothesis
Cultural life script hypothesis
31
32
Table 7-1, p. 242
Reminiscence bump :
life-narrative hypothesis

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People assume their life identities during that
time
It is time when lots of “first” occur
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Going to college
Committing to a partner
Starting a career
It is time of “Our” generation
It is time that people return to when they
become nostalgic for the “good old days”
33
Reminiscence bump :
cognitive hypothesis
Encoding is better during periods of rapid change
that are followed by stability
 Adolescence and young adulthood fit this
description
 Memory of immigrants


Robert Schrauf and David Rubin 1998
Shows the memory curves for two groups of
immigrants
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Reminiscence bumb occurs at normal age for people who
emigrated early
But is shifted to 15 years later for those who emigrated
34
later
35
Fig. 7-5, p. 242
Reminiscence bump :
cultural life script hypothesis
Events in a person’s life story become
easier to recall when they fit the cultural
life script for that person’s culture
Person’s life story :

all of events that have occurred in a
person’s life
36
Reminiscence bump :
cultural life script hypothesis
Cultural life script :
 The events that commonly occur in a particular
culture

Most occur during reminiscence bump

Dorthe Berntsen and David Rubin 2004

Asked people to list when important events in a typical
person’s life usually occur
 Falling in love (16 years)
 College (22 years)
 Marriage (27 years)
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 Having children (28 years)
Chapter summery 6

The following hypotheses have been
proposed to explain the reminiscence bump
1.
Life-narrative
2.
Cognitive
3.
Cultural life script
38
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39
Flashbulb memories
The assassination of President John F. Kennedy
on Nov.22,1963
The terrorist attacks of September 11, 2001
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Do you remember when you first heard about
the attacks ?
How you found out ?
Where you were ?
Your initial reaction ?
What you did next ?
40
41
Fig. 7-6, p. 243
Flashbulb memories
I remember walking into the psychology
department office and hearing from a
secretary that someone had crashed a plane
into the World trade center. At the time , I
picture a small private plane that had gone off
course , but a short while later , when I called
my wife from a pay phone near my classroom
, she told me that the first tower of the World
Trade Center had just collapsed. Shortly after
that , in class , my students and I discussed
what we knew about the situation and
decided to cancel class for the day.
42
Flashbulb memories :
Roger Brown and James Kulik 1977
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A person’s memory for the circumstances
surrounding hearing about shocking , highly
charged important events.
Not memory for the event itself
Remember for long periods of time + more
details
Likened the process of forming a memory to
the taking of a photograph
43
Chapter summery 7

Brown and Kulik proposed the term flashbulb
memory to refer to a person’s memory for the
circumstances surrounding hearing about
shocking , highly charged , important events.

They proposed that these flashbulb
memories are vivid and detailed like
photographs.
44
Flashbulb memory
Brown and Kulik’s idea

The mechanism responsible for these vivid
and detailed memories as a “Now Print”
mechanism , as if these memories are
created like a photograph that resists fading.

Problem : Accuracy ???
45
Flashbulb memories
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Check for accuracy

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Compare the persons memory to reports
collected immediately after the event.
This technique called repeated
recall
46
Repeated recall
Idea : memory changes over time
 Test : compare baseline reports with
later reports


Baseline report


The person’s memory is first measured
immediately after a stimulus is presented or
something happens
Later report

Days , months , or years later , when
participants are asked to remember what
had happened
47
Repeated recall

Shown that flashbulb memories are not like
photographs

Flashbulb memories change over time
Main finding : people report that memories
surrounding flashbulb events are

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Especially vivid
Often inaccurate
Lacking in detail
48
Repeated recall

Ulric Neisser and N. Harsch 1992

Asked participants how they heard about the
explosion of the space shuttle Challenger that
occurred in 1986

Participants filled out a questionnaire within a day
after the explosion

Then filled out the same questionnaire 2 ½ to 3
years later
49
50
Fig. 7-7, p. 245
A day after explosion
I was in my religion class and some people
walked in and started talking about (it).
 I didn’t know any details except that it had
exploded and the schoolteacher’s students
had all been watching , which I thought was
so sad.
 Then after class I went to my room and
watched the TV program talking about it.
 I got all details from that

51
2 ½ years later




When I first heard about the explosion I was
sitting in my freshman dorm room with my
roommate , and we were watching TV.
It came on a news flash , and we were both
totally shocked.
I was really upset , and I went upstairs to talk
to a friend of mine.
And then I called my parents
52
Challenger explosion

Right after explosion


2 ½ years later


21 % indicated that they first heard about it on TV
45 % indicated that they first heard about it on TV
Reasons for increase TV memories


TV reports become more memorable through
repetition
TV is a major source of news
53
The announcement of the O.J. Simpson
murder trial verdict on Oct 3,1995
Heike Schmolck and coworkers 2000
 Determine accuracy of memories for an event can
be influenced by other experiences
 Comparing participants’ report (3-day & 32-day)


Response 3-day :
 I was in the commuter lounge at college and saw it on TV
as 10.00 approached , more people came into the room
Response 32-day :
 I first heard it while I was watching TV at home in my living
room. My sister and father were with me …..
54
Chapter summery 8


A number of experiments indicate that it is not
accurate to equate flashbulb memories with
photographs because , as time passes , people
make many errors when reporting flashbulb
memories
Studies of memories for hearing about both the
Challenger explosion and the announcement of
the O.J. Simpson murder trial verdict showed
that people’s responses became more
inaccurate with increasing time after the event.
55
Flashbulb memory
Inaccurate response in Challenger and O.J. Simpson :
Flashbulb memories may decay just like
regular memories
This idea support by : Talarico & Rubin 2003
56
Talarico & Rubin 2003
Experiment in a group of college students

Asked a number of questions on Sep 12 , 2001

Questions were about the terrorist attacks


When did you first hear the news ?
Questions were about everyday event
 Participants created a two- or three-word
description that could serve as a cue for that event in the
future

Retested later (1 week , 6 weeks , 32 weeks)
57
Talarico & Rubin 2003
Results ( figure 7.8 a )

Participants remembered fewer details and
made more errors at longer intervals after the
events

Little difference between the results for the
flashbulb and everyday memories
58
Talarico & Rubin 2003
Figure 7.8 b

People’s belief that their memories were
accurate stayed high over the entire 32-week
period for flashbulb memories , but dropped
for the everyday memories.

Belief : have a difference between flashbulb
and everyday memories
59
60
Fig. 7-8, p. 247
Flashbulb memory :
Talarico and Rubin’s results

People think the memories are stronger
and more accurate
Reality
 This study found that there was little or no
difference between flashbulb and everyday
memories in terms of the amount
remembered and the accuracy of what is
remembered
61
Patrick Davidson and
coworkers 2006

Found that memories for events associated
with hearing about 9/11
were more resistant to fading than
memories for other events that took place at
that time.
62
Patrick Davidson and
coworkers 2006
Asked participants questions
shortly after 9/11 attack
& 1 year later (given a cue : party or movie)

Question about flashbulb events
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


How did you hear the news ?
Where were you when you heard about the attack ?
Who was present ?
Question about everyday events
63
Patrick Davidson and
coworkers 2006
“Congruence score”
0 points : couldn’t remember ,or inaccurately
1 points : partially correct or less specific than
original memory
2 points : very similar to their original report
Adding the points for all of the questions and
scaling the total so that 1.0 was maximum
64
Patrick Davidson and
coworkers 2006
Figure 7.9 a

Congruence for 9/11 were fairly high 1 year
later ( 0.77 )

Congruence for everyday events was much
lower ( 0.33 )
65
Patrick Davidson and
coworkers 2006
Figure 7.9 b

All of participants had no trouble
remembering 9/11

Only 65 % of the participants were able to
remember what the everyday event was ,
even after being prompted with a cue
66
67
Fig. 7-9, p. 248
Patrick Davidson and
coworkers 2006
More difficult to remember their everyday event

Participants were not aware that they would
be tested later (the 1-year test was a
surprise)

The retrieval cue they were given may not
have been as effective as Talarico and
Rubin’s
68
Retrieval cues
Timo Mantyla’s
 Retrieval cues are more effective when they
are created by the participant than when they
are created by someone else
Talarico and Rubin’s
 Participants created their own retrieval cues
Davidson’s
 Participants did not created retrieval cues
69
Patrick Davidson :
why better flashbulb memory
Two characteristics of flashbulb memories
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Involve high emotions
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Surprise , Disbelief , Anger , Fear
High emotions trigger Amygdala  better memory
Narrative rehearsal hypothesis


How many times did you see the planes crashing into the
World Trade Center replayed on TV ?
How much did you read about events surrounding 9/11 or
talk about them with other people ?
70
Chapter summery 9



Talarico and Rubin’s study of people’s memory for when
they first heard about the 9/11 terrorist attack indicates that
memory errors increased with time , just as for other
memories , but that people remained more confident of the
accuracy of their 9/11 memory.
Another 9/11 study , by Davidson and coworkers , also
showed that memory for 9/11 declined with time , but that
people had better memory for the events surrounding 9/11
than for another more ordinary event that had occurred at
the same time.
The difference in these results might be explained by
differences in the procedure in these two experiments
71
Constructive nature of memory
Memories are constructed by the person
(may distort or change things that happened)
 Based on :

What actually happened

Plus additional factors :



experiences ,
person’s knowledge ,
expectations
72
The War of the Ghosts
One night two young men from Egulac went down to the river to hunt seals , and while
they were there it became foggy and clam. Then they heard war cries , and they
thought : “Maybe this is a war party.” They escaped to the shore and hid behind a
log. Now canoes came up , and they heard the noise of paddles and saw one canoe
coming up to them. There were five men in the canoe , and they said :
“What do you think ? We wish to take you along. We are going up the river to make war
on the people.”
One of the young men said : “I have no arrows” “Arrows are in the canoe,” they said. “I
will not go along. I might be killed. My relatives do not know where I have gone. But
you,” he said, turning to the other, “may go with them.”
So one of the young men went, but the other returned home. And the warriors went on
up the river to a town on the outer side of Kalama. The people came down to the
water , and they began to fight , and many were killed. But presently the young man
heard one of the warriors say : “Quick, let us go home; that Indian has been hit.” Now
he thought: “Oh, they are ghosts.” He did not feel sick , but they said he had been
shot.
So the canoes went back to Egulac, and the young man went ashore to his house and
made a fire. And he told everybody and said : “Behold I accompanied the ghosts, and
we went to fight. Many of our fellows were killed, and many of those who attacked us
were killed. They said I was hit, and I did not feel sick.”
He told it all , and then he became quiet. When the sun rose, he fell down. Something
black came out of his mouth. His face became contorted. The people jumped up and
cried. He was dead.
73
Bartlett’s “ War of the ghosts ” experiment
British psychologist Fredrick Bartlett
 Participants read the following story from
Canadian Indian Folklore
 Bartlett asked them to recall it as accurately
as possible
Repeated reproduction (similar to repeated recall)

The same participants came back a number
of times to try to remember the story at
longer and longer intervals after they first
read it.
74
Bartlett’s “ War of the ghosts ” experiment
The errors Bartlett’s participants made

Forgot much of the information in the story

Most participants’ reproductions of the story



were shorter than the original
contained many omissions
inaccuracies
75
Bartlett’s “ War of the ghosts ” experiment
Interpreted these errors

The strangeness of the story
(Myth from an unfamiliar culture)


Story : Canadian folklore
Participants : Edwardian England
 Canoes
 Boats
76
Bartlett’s “ War of the ghosts ” experiment
The changes that occurred in the remembered
stories tended to reflect the participants’ own
culture

Constructive memory


Constructive processes that influence memory
during encoding
Reconstructive memory

….During retrieval
77
Educated guesses about high
school grades


College students were asked to remember
their high school grades
Checking the students’ report against their
high school transcripts



Accurately remembered A grades 89%
Accurately remembered D grades 29%
79 of 99 students inflated their grades by
remembering some of them as being higher than
what they actually received
78
Educated guesses about high
school grades
Reasons of errors
 People tend to remember “positive events”
more readily than negative events


A or B would be remembered better than C or D
Take a “best guess” approach

Participants constructed their memory based on
their general experience of receiving grades in the
part
79
Chapter summery 10



According to the constructive approach to memory ,
what people report as memories are constructed by the
person based on what actually happened plus
additional factors such as the person’s knowledge ,
experiences , and expectations.
Bartlett’s “War of the Ghosts” experiment and the
experiment in which students were asked to remember
their high school grades both resulted in many memory
errors.
These errors can be explained in terms of the
constructive process of memory.
80
Source monitoring and
source monitoring errors

Source memory :


The process of determining the origins of our
memories , knowledge , or beliefs
Source monitoring error
(source misattributions) :

Misidentifying the source of a memory
81
Source misattributions
“Did you hear about the new movie Brokeback
mountain that opened last week?”
“Yes, I read about it in the times.”
“Really? Sam told me about it, or maybe it was
Bernita. I can’t remember.”
82
Larry Jacoby and coworkers 1989 :
Becoming famous overnight
Demonstrates an effect of source monitoring errors
 Testing participants’ ability to distinguish between
famous and non famous names




Made-up nonfamous name :
Sebastian Weissdorf , Valerie Marsh
Participants read a number of nonfamous names
Immediate test
Delayed test
83
Larry Jacoby and coworkers 1989 :
Becoming famous overnight
Immediate test
 Right after the participants saw the list of nonfamous
names


Just before this test, participants were told that all of the
names they had just seen were nonfamous
Participants were told to pick out the names of
famous people from a list

A list containing
 The ( just seen ) nonfamous names
 The ( never seen ) nonfamous names
 Famous names
84
85
Fig. 7-10, p. 253
Larry Jacoby and coworkers 1989 :
Becoming famous overnight
Results :
Immediate test
 Most nonfamous names correctly identified
as nonfamous
Delayed test ( 24 hours later )

Some nonfamous names misidentified as
famous
86
How did Sebastian Weissdorf
become famous overnight ?
24 hours since you first saw the names
 You now have to decide whether Sebastian
Weissdorf is famous or not
 You ask yourself the question : Why is this
name familiar ?
 If you decide that the familiarity was caused
by fame (Source monitoring errors)
 So Sebastian Weissdorf become famous
87
Chapter summery 11



Source memory is the process of determining
the origins of our memories , knowledge , or
beliefs.
A source monitoring error occurs when the
source of a memory is misidentified.
Jacoby’s “becoming famous overnight”
experiment illustrates an effect of source
monitoring errors.
88
Everyday memory
& Memory errors
Part II
พญ. กาญจนา พิทกั ษ์วฒั นานนท์
89
Demonstration :
Reading sentences

Read the following sentences


Fill-in-the-blank exercise


The new baby stayed awake all night
The new baby ____ all night
Errors 3/5 : pragmatic inference

Stayed awake became cried
90
Making inferences

Memory reports can be created by inferences
based on a person’s experiences and
knowledge

A baby stayed awake all night does not
include any information about crying,
knowledge about babies might lead a person
to infer that the baby was crying.
91
92
Fig. 7-11, p. 255
Schemas and Scripts

Schemas : knowledge about what is involved
in particular experience


Although there were no books in the office, 30
percent of the participants reported that they saw
books.
Script : conception of the sequence of actions
that usually occur during a particular
experience

Bill checked in with the dentist’s receptionist
93
94
Fig. 7-12, p. 257
Remembering a list of words
: false memory

Memory for a list

Bed , rest , awake , tired , dream , wake , night ,
blanket , doze , slumber , snore , pillow , peach, yawn
, drowsy

Remembering “sleep” is a false memory
because it isn’t on the list

Effect of schemas : constructive processes
have created an error in memory.
95
The advantages and
disadvantages of construction

Creativity helps us “fill in the blanks” when
there is incomplete information.

Survival value

Erroneous perception

Memory errors in courtroom
96
97
Fig. 7-13, p. 260
Memory can be modified or
created by suggestion
Misinformation effect




Suggestion
Advertisements
Political arguments
Opinion makers
98
The misinformation effect

Misleading postevent information (MPI)

Misleading information presented after a person
witnesses an event can change how that person
describes that event later

Smashed : 41 miles/hour , 32% see broken glass
Hit : 34miles/hour , 14% see broken glass

99
100
Fig. 7-14, p. 262
Presenting misleading
postevent information
101
102
Fig. 7-15, p. 263
103
Table 7-2, p. 264
Creating false memories for
early events in people’s lives
104
105
Fig. 7-16, p. 266
Why do people make errors in
eyewitness testimony ?
106
Errors of eyewitness
identification
107
The crime scene and afterward
108
Errors associated with
attention
109
110
Fig. 7-17, p. 269
Errors due to familiarity
111
112
Fig. 7-18, p. 270
113
Fig. 7-18a, p. 270
114
Fig. 7-18bc, p. 270
Errors due to suggestion
115
116
Fig. 7-19, p. 272
Increasing confidence due to
postevent questioning
117
What is being done ?
118
119
Fig. 7-20, p. 273
120
Fig. 7-21, p. 274
Memories of childhood abuse
121
Chapter summery 12

Inference is one of the mechanisms of the
constructive process of memory.

The following experiments show that
inference can cause memory errors



Pragmatic inference
Bransford and Johnson’s “pounding nail”
The baseball story
122
Chapter summery 13

Our knowledge about what is involved in a
particular experience is a schema for that
experience

The experiment in which participants were
asked to remember what was in an office
illustrates how schemas can cause errors in
memory reports
123
Chapter summery 14

A script is our conception of the sequence of
actions that usually occur during a particular
experience.

The “dentist experiment” in which a
participant is asked to remember a paragraph
about going to the dentist , illustrates how
scripts can result in memory errors.
124
Chapter summery 15

The experiment in which people were asked
to recall a list of words related to sleep
illustrates how our knowledge about things
that belongs together (for example , that
sleep belongs with bed) can result in
reporting words that were not on the original
list.
125
Chapter summery 16

Although people often think that it would be
an advantage to have a photographic
memory , the case of the memory expert S
shows that it may not be an advantage to be
able to remember everything perfectly.

The fact that our memory system does not
store everything may even add to the survival
value of the system
126
Chapter summery 17



Experiments in which misleading post event information is
presented to participants in memory experiments indicate
that memory can be influenced by suggestion.
An example of such an experiment is Loftus’s trafficaccident experiment
The following explanations have been proposed to explain
the errors caused by misleading post event information




Memory-trace hypothesis
Effect of retroactive interference information
Effect of source monitoring errors
Lindsay’s experiment provides support for the source
monitoring explanation , but the reasons for the effect of
MPI are still being debated by memory researchers
127
Chapter summery 18



An experiment by Hyman showed that it is
possible to create false memories for early
events in a person’s life
A similar experiment by Lindsay showed that
this false-memory effect for early events can
be made stronger by showing the participants
a picture of their first- or second-grade class.
DuBreuil was able to show that false
memories can be created for events that
supposedly occurred early in infancy
128
Chapter summery 19


There is great deal of evidence that eyewitness testimony
about crimes can be prone to memory errors.
Some of the reasons for errors in eyewitness testimony
are




Not paying attention to all relevant details , due to the emotional
situation during a crime (weapons focus is one example of such an
attentional effect)
Errors due to familiarity , which can result in misidentification of an
innocent person due to source monitoring error
Errors due to suggestion during questioning about a crime (the
“Good , you identified the suspect” experiment illustrates how a
police officer’s responses can cause memory errors)
Increased confidence due to post event questioning
129
Chapter summery 20

Cognitive psychologists have made a number
of suggestions of ways to decrease errors in
eyewitness testimony
130
Chapter summery 21



The problem of childhood sexual abuse is serious
and widespread
There is the potential , however , that false
memories for abuse could be created by some of
the techniques used by therapists to try to help
their patients remember events in their past
The problem of differentiating between accurate
memories of abuse and false memories created in
the therapy situation is a serious one because
there is no test or procedure that can accurately
differentiate between real memories and false
memories
131