Source Monitoring & Eyewitness Memory
Psychology 355: Cognitive Psychology
Instructor: John Miyamoto
05/11/2016: Lecture 07-3
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Outline
• Memory is constructive
• Eyewitness memory
• Source monitoring and source monitoring errors
• Errors in eyewitness memory
Psych 355, Miyamoto, Spr '16
Advantages & Disadvantages of Constructive Memory
2
Constructive Memory
Advantages
Disadvantages
• Helps to create a meaningful narrative
about our life experiences.
• Sometimes our memories are based on
expectations and not on the actual
experience.
• Allows us to fill in the gaps in our
knowledge.
• Speeds up how quickly we can interpret
or respond to a situation.
• Schemas help organize experiences into • Sometimes we make errors without
"chunks" that are easier to manipulate in
realizing it.
working memory, and easier to associate
with similar experiences.
Intro to Eyewitness Testimony
Eyewitness Testimony
• Basic source of evidence in the Anglo-American legal system.
• Historically more trusted than circumstantial evidence.
• Of 341 people who were exonerated by DNA evidence as of 2012,
eyewitness testimony played a role in 75% of the original convictions.
(Quinlivan et al., 2009; Scheck et al., 2000).
Psych 355, Miyamoto, Spr '16
Sources of Error in Eyewitness Testimony
4
Sources of Error in Eyewitness Memory
• Intrinsic fallability of memory
• Misleading familiarity
• Cross-racial identification
• Feedback can reinforce memory errors
• Line ups versus show ups.
♦
Line up: Did one of these men do it?
(People tend to respond as if the question is, who in this group
looks the most like the person you saw?)
♦
Sequential show up: Did Man A do it? Did Man B do it? etc.
(Surprisingly less biased)
• Post-event suggestions by interested parties, esp. police.
♦
Misleading post-event information (MPI) can bias memory
♦
Misinformation effect
Psych 355, Miyamoto, Spr '16
Source Monitoring & Source Misattribution
5
Source Monitoring & Source Misattribution
• Source monitoring - retaining a memory for the source of information
in memory.
• Source misattribution - attributing a memory to one source when the
actual source was something else.
♦
Example: My friends tell me about a large building fire that they
witnessed. Years later I believe that I witnessed this fire along with my
friends.
Psych 355, Miyamoto, Spr '16
Source Misattribution & Errors in Eyewitness Memory
6
Source Misattribution is One Cause
of Erroneous Eyewitness Memory
• Source misattribution can cause errors in eyewitness testimony.
♦
A familiar face is more likely to be falsely identified as a perpetrator
of a crime (witness thinks the familiarity is due to seeing this person
commit the crime).
♦
Example: A woman was attacked in her home shortly after watching
a TV show in which a psychologist, David Thompson, was interviewed.
Later she identified David Thompson as the attacker.
(He had an alibi, the interview on the TV show.)
• Remember/Know Distinction:
♦
Feeling of familiarity ≠ Recollection
but people may say that they "remember" Mr. X when Mr. X is familiar.
Psych 355, Miyamoto, Spr '16
Ross et al. Experimental Study of Source Misattribution
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Source Misattribution & Eyewitness Identification
See Figure 8.17 in Goldstein
Robber Not Present
Try to pick robber
from photospread;
male teacher present
Experimental
View male teacher
reading to students
Both Conditions
View female
teacher getting
robbed by a man.
Robber Present
Control
View female
teacher reading to
students
Try to pick robber
from photospread;
male teacher present
Ross, D. F., Ceci, S. J., Dunning, D., & Toglia, M. P. (1994). Unconscious transference and mistaken identity:
When a witness misidentifies a familiar but innocent person. Journal of Applied Psychology, 79, 918-930.
Psych 355, Miyamoto, Spr '16
Same Slide with Emphasis Rectangles
8
Source Misattribution & Eyewitness Identification
See Figure 8.17 in Goldstein
Robber Not Present
Try to pick robber
from photospread;
male teacher present
Experimental
View male teacher
reading to students
Both Conditions
View female
teacher getting
robbed by a man.
Robber Present
Control
View female
teacher reading to
students
Try to pick robber
from photospread;
male teacher present
Ross, D. F., Ceci, S. J., Dunning, D., & Toglia, M. P. (1994). Unconscious transference and mistaken identity: When a
witness misidentifies a familiar but innocent person. Journal of Applied Psychology, 79, 918-930.
Psych 355, Miyamoto, Spr '16
Results of This Study
9
Results of Ross et al. (1994)
Figure 8.20: Ross et. al. (1994)
• 60% id male teacher
when robber not
in photospread.
20% id teacher in
control group.
♦
10% id teacher in
control group.
• Source misattributions
can cause mistaken
identifications.
60
% Identification
of Male Teacher
• 18% id male teacher
when robber in
photospread.
% Identification
of Male Teacher
♦
40
20
0
E
C
Robber not in
photospread
60
40
20
0
E
C
Robber in
photospread
E = Experimental Condition = View male teacher at stage 1
C = Control Condition = View female teacher at stage 1
Psych 355, Miyamoto, Spr '16
Misinformation Effect
10
Lineups versus Show-Ups – What Are They?
• Classic showup: Police show only one person to a witness.
Question: "Is he the man you saw?"
• Classic lineup: Police show 7 people to the witness:
Question: "Do you see the perpetrator in the line up?"
• Improved showup = sequential showup: Police tell the witness,
"We're going to show you a series of men (of unstated length).
Stop me when you see the perpetrator."
• Contrary to most people's expectations, show ups are more accurate
than line ups. Why are showups more accurate than lineups?
Psych 355, Miyamoto, Spr '16
Why Lineups & Showups Differ as Cognitive Tasks
11
Cognitive Differences Between Lineups and Showups
• Classic showup:
♦
Witness asks himself/herself: "Did I see this person do the crime?"
• Classic lineup:
♦
Witness assumes that the perpetrator is in the lineup.
Mistake!
♦
Witness asks himself/herself:
"Which of these men looks the most like the person that I saw?"
Mistake!
• Sequential presentation = sequential showup
(Goldstein refers to this a sequential presentation)
♦
With each person, the witness asks himself/herself:
"Am I sure that this is the person who I saw do the crime?"
• Lindsey & Wells (1985) found that the sequential showup greatly reduced
false id when the perpetrator was not present (43% vs 17%)
• Sequential showups slightly reduced the rate of true id when perpetrator is
present.
Psych 355, Miyamoto, Spr '16
Misinformation Effect
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Misinformation Effect
MPI = Misleading Postevent Information
Overview of the Misinformation Effect
• Subject sees a video, or a slide sequence, or reads a story.
I'll call this "the video." The video usually depicts a crime.
• After seeing the video, the subject is asked questions about
it. For some subjects, the questions contain misinformation
(MPI or false assumptions).
• Subjects receive a memory test. A misinformation effect is
found if subjects who heard the misleading questions
remember the video in a way that is consistent with the
question and not the video.
Psych 355, Miyamoto, Spr '16
Introduce Loftus & Palmer - Car Crash
13
MPI: Leading Questions Can Produce Memory Biases
Loftus & Palmer (1974)
• Subjects see film of an
auto accident.
• Questions contained
alternative descriptions
of the accident.
Psych 355, Miyamoto, Spr '16
Results: Effect of the Biased Questions
14
Leading Question Can Produce Memory Biases
Psych 355, Miyamoto, Spr '16
Verb
Estimated Speed
smashed
40.8
collided
39.3
bumped
38.1
hit
34.0
contacted
31.8
Loftus & Palmer Result for Broken Glass
15
Leading Questions Can Produce False Inferences
• One week later, subjects were asked: Did you see any broken glass?
Actually, there was no broken glass in the film.
Yes
No
"smashed"
32
68
"hit"
14
86
control*
12
88
* The control group were not asked about the speed of the car
(no misinformation; no correct information).
UW: Psych 355, Miyamoto, Win '12
Misinformation Effect - Loftus, Miller & Burns
16
Misinformation Effect:
Loftus, Miller, & Burns (1978)
Subjects watch slides that show
a traffic accident: Car A runs a
stop sign and hits Car B.
• Consistent Info Condition:
How fast was Car A going
when it went past the stop sign?
• Inconsistent Info Condition:
How fast was Car A going
when it went past the yield sign?
• Memory test:
Did Car A go past a stop sign or a yield sign?
Psych 355, Miyamoto, Spr '16
Results of Loftus, Miller & Burns Experiment
17
% Correct Identification
of the Stop Sign
60
Consistent Info
40
Neutral Info
Inconsistent Info
Misinformation
Effect
0
20
Percent Correct
80
100
Results of Loftus, Miller & Burns (1978)
0 20
1
min. day
2
days
1
week
Retention Interval
• A misinformation effect was found (it gets larger over time)
Psych 355, Miyamoto, Spr '16
Chan: Recalling an Event Increases Susceptibility to Misinformation
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Recalling an Event Increases
Susceptibility to Misinformation Effects
Chan, J. C. K., Thomas, A. K., & Bulevich, J. B. (2009). Recalling a witnessed event increases eyewitness
suggestibility. Psychological Science, 20, 66–73.
• Subjects view tape of "24" TV program.
• Misinformation: A terrorist knocks out flight attendant with an injection of a
drug, but the misinformation assumes that a chloroform pad was used.
• Cued recall test increases tendency to recall misinformation.
Psych 355, Miyamoto, Spr '16
Feedback Can Increase Confidence in Erroneous Memories
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Feedback Can Increase Confidence in Erroneous Memories
• Subjects viewed video of crime.
• Subjects shown a photo array that
did not contain the perpetrator of
the crime.
• All subjects picked someone from
the photo array. (!!!)
• Confirming Feedback Condition:
"Good, you identified the suspect."
• No Feedback Condition
• Disconfirming Feedback Condition:
"Actually the suspect was number
__."
• Later when asked how confident they
were in their identifications, subjects
were most confident with confirming
feedback.
Psych 355, Miyamoto, Spr '16
APA Recommendations for Use of Eyewitness Memory in Courts
20
Recommendations for Improving Eyewitness Memory
• Use a sequential showup
(Goldstein would call it a sequential presentation).
• In a showup, use non-suspects who are similar to a suspect.
• Inform witness that the perpetrator may not be in a showup.
• Administrator of showup should not know who is the suspect.
• Get confidence rating immediately after the initial identification.
Avoid giving feedback to the witness after the lineup
• Use cognitive interview techniques; do not prompt the witness
with leading questions.
♦
See Wikipedia article on cognitive interview techniques:
http://en.wikipedia.org/wiki/Cognitive_interview
Psych 355, Miyamoto, Spr '16
Memory Accuracy & Memory Errors - END
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Memory Accuracy & Memory Errors
• Psychologists are not claiming that memories are mostly errors.
• We need to be aware that errors do occur, especially in situations
where beliefs about memory accuracy have great practical
importance.
• In general, people are overconfident in the accuracy of their memories.
Psych 355, Miyamoto, Spr '16
END - or Continue to Outline of Recovered Memories Topic
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Wednesday, May 11, 2016: The Lecture Ended Here
Psych 355,, Miyamoto, Spr '16
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