Memory Errors, Memory Gaps
Reasons why we remember so much
and so little at the same time...
Memory and its failures
• Semantic activation & Inferences
• Schemas
• Update of memory
Semantic Activation
• Example:
– You will hear a list of words, once the list ends, recall
as many words as possible
– Bed, Rest, Awake, Snooze, Tired, Dream, Blanket, Doze, Slumber, Snore,
Nap, Yawn, Drowsy
– Missing word: ‘sleep’
Inference in Recognition Memory
with the hammer
• John was trying to fix the bird house. He was pounding
the nail when his father came out to watch him and to help
him do the work.
with the hammer
• John was trying to fix the bird house. He was looking for
the nail when his father came out to watch him and to help
him do the work.
Recognition test: “John was using the hammer to fix
the bird house when his father came out to watch him
and to help him do the work.”
Schema (script):
A high-level representation of knowledge about familiar situations.
Schemata help us to deal with the world efficiently by representing
those aspects of our experience that are usually the same from one
time to another…
Event Schema (script): Going to a restaurant
• Enter
–
–
–
–
–
Walk into restaurant
Look for table
Decide where to sit
Go to table
Sit down
• Order
–
–
–
–
–
–
Get menu
Choose food
Waiter arrives
Give orders to waiter
Wait, talk
Cook prepares food
• Eat
–
–
–
–
Cook gives food to waiter
Waiter delivers food
Eat
Talk
• Leave
–
–
–
–
–
–
–
Waiter delivers bill
Examine bill
Calculate tip
Leave tip
Get belongings
Pay bill
Leave restaurant
“Office Stuff” Schema
“Office Stuff” Schema
• Good memory for:
– atypical items: wine bottle, skull
– items consistent with schema: desk, chair (response bias?)
• Poor memory for:
– Infrequent items consistent with schema: bulletin board
• False memory for things
– Frequent items consistent with schema but absent (books)
Memory Update: Misinformation Effect
• See event: film of two-car accident
• Receive misinformation
– When the cars smashed each other,
– When the cars hit each other,
• Memory test: the speed was …
– a) “smashed”
– b) “hit”
(Elizabeth Loftus)
(41 mph)
(34 mph)
Is this a ‘memory’ distortion, or a report bias?
A week later: Did you see broken glass? (correct answer: no)
a) “smashed”: 32% yes
b) ‘hit’:
14% yes
(Loftus & Palmer, 1974)
Misinformation Effect: Another example
• See event: film of two-car accident
• Receive misinformation: ‘...as the car passed the
– “stop sign”
– “yield sign”
(non-mislead Ss)
(mislead Ss)
• Memory test: Did the car pass a:
stop sign
stop sign
OR
OR
yield sign?
Misled subjects make error
no-U turn sign? Misled subjects better than
chance (50%)
(McCloskey & Zaragoza, 1985)
Is the original memory lost?
stop
yield
stop
“yield”
time
event
misinformation
new memory
• False memory does not supplant original memory.
• False memory stronger than original memory.
Relevance to Criminal Justice System
• most obvious case
– crime
--> study
– picture of suspect --> misinformation
– Lineup
--> test
• Eyewitness may recognize suspect from police display, not from crime
scene.
• Conclusions:
– Do not let potential witnesses see suspects.
– Interrogate without asking leading questions (Capturing the Freedmans)
• Further sources of error:
– newspaper stories, etc.
Memory Contamination & Psychotherapy
•Therapist repeatedly asks child about abuse at day care
center. Eventually, child “remembers” abuse.
•Therapist repeatedly asks woman about childhood abuse.
Eventually, woman “recovers repressed memory” of abuse.
Are these repressed memories or false memories?
Big debate! (Loftus vs. Freyd)
Mechanisms of Forgetting
1. Decay of Traces (??)
2. Retrieval Failure
3. Interference from new material
Method: Paired-Associate Learning
Study phase:
CHAIR-92
FROG-41
…
Test phase:
CHAIR?
Correct answer: 92.
Retroactive Interference
Group 1
Group 2
1.
Learn A-B List
Learn A-B List
2.
Learn A-C List
----
3.
Test on A-B List
Test on A-B List
^^^^^^^^^
This Groups Performs
Worse.
The process of learning the A-C list causes
active disruption of the A-B memories.
Proactive Interference
Group 1
Group 2
1.
Learn A-C List
----
2.
Learn A-B List
Learn A-B List
3.
Test on A-B List
Test on A-B List
^^^^^^^^^
This Groups Performs
Worse.
Does Decay Exist, too?
Hard to test!
Reisberg:
•Cockroaches.
•Sleep (Jenkins & Dallenbach)
From the Courage To Heal, by Bass & Davis, 1988
You may think that you don’t have memories, but often as
you begin to talk about what you do remember, there
emerges a constellation of feelings, reactions, and recollections
that add up to substantial information. To say, “I was abused,”
you don’t need the kind of recall that would stand up in a
court of law. Often the knowledge that you were abused
starts with a tiny feeling, an intuition ... Assume your feelings
are valid. So far, no one we’ve talked to thought she might have
been abused, and then later discovered that she hadn’t been.
The progression always goes the other way, from suspicion
to confirmation. If you think you were abused and your life
shows the symptoms, then you were.
(p. 22).