Transcript 2320Lecture25

Repressed Memories
Elizabeth Loftus
Recalling Episodic Memory
• Recall is a generative processes rather
than simply calling up stored data
Recalling Episodic Memory
• Recall is a generative processes rather
than simply calling up stored data
• Evidenced by the fact that episodic
memories can be distorted or
completely false under certain
circumstances
Recalling Episodic Memory
• Misinformation Effect - exposure to
information subsequent to storage of
memory can alter the contents of the
memory
Recalling Episodic Memory
• Misinformation Effect
• Consider the following example:
– Subjects were shown a video depicting a car
accident
– Then given the following question: “How fast were
the vehicles going when they ______”
– Different subjects were asked questions that
differed in the “magnitude” of the final word
– The possible words were: Contacted, Hit,
Bumped, Collided, and Smashed
Recalling Episodic Memory
• Misinformation Effect
• Consider the following example:
– Average estimated velocity depended on
the nature of the question
Recalling Episodic Memory
• Misinformation Effect
• Interpretation:
– Episodic memory can be distorted by
subsequent information
Recalling Episodic Memory
• False Memories may arise when details
of a crime are in question as in eyewitness testimony or repressed
memories of abuse during childhood
What is the distinction between a false memory
and a distorted memory? What do they have in
common?
“Derepressed memories”
• Loftus opens with several examples of
court cases that involve “derepressed
memories”
• What is a repressed memory?
• What is a derepressed memory?
Loftus’ position in this article
• Loftus does not reject the notion of
repressed memories
– 18% - 59% of abuse survivors report
having regained access to previously
repressed memories
Loftus’ position in this article
• Loftus does not reject the notion of
repressed memories
– 18% - 59% of abuse survivors report
having regained access to previously
repressed memories
• What does Loftus challenge?
Loftus’ position in this article
• Loftus does not reject the notion of
repressed memories
– 18% - 59% of abuse survivors report
having regained access to previously
repressed memories
• What does Loftus challenge?
…That all “de-repressed” memories are accurate memories.
High Stakes
• Survivor of real
abuse might struggle
for years or decades
with consequences
and need to confront
the repressed
memory in order to
recover emotionally
• False accusation could
tear family apart and
send an innocent
person to jail
What’s the issue?
• What does Loftus express concern about regarding
the derepression of memories?
What’s the issue?
• What does Loftus express concern about regarding
the derepression of memories?
– reality of the memory is in question if it is recalled under
certain circumstances
What’s the issue?
• What does Loftus express concern about regarding
the derepression of memories?
– reality of the memory is in question if it is recalled under
certain circumstances
• What is the course of events that Loftus finds
worrisome?
What’s the issue?
• What does Loftus express concern about regarding
the derepression of memories?
– reality of the memory is in question if it is recalled under
certain circumstances
• What is the course of events that Loftus finds
worrisome?
This memory might
be false!
Therapist or Popular
Book suggests that
patient consider
possibility of abuse
Patient engages in
intense effort to
recall
An explicit
episodic
memory is
achieved
What’s the issue?
• So we potentially have a situation in which
someone who is having troubles in life and is
seeking answers is told to determine whether
or not memories for abuse exist
• What are some techniques that are used to
“assist” recollection?
What’s the issue?
• So we potentially have a situation in which
someone who is having troubles in life and is
seeking answers is told to determine whether
or not memories for abuse exist
• What are some techniques that are used to
“assist” recollection?
– hypnosis, imagery, dream analysis, story telling
– Loftus presents evidence that such processes
may lead to invalid memories or overconfidence in
the validity of memories
Conclusion:
• We cannot know with certainty (without corroborating
evidence) whether a derepressed memory is true
• Therapists should engage in probing this possibility
very carefully
– avoiding suggestive questions
– remaining unconvinced without corroborating
evidence
– being “gently confrontational” to encourage patient
to consider the possibility that the events didn’t
happen
Subconscious Cognition?!
What you don’t know, might help
you…or it might not!
Perception and Cognition
• We have elaborate perceptual
mechanisms to provide information to
our brains to guide current or future
behavior
Perception and Cognition
• We have elaborate perceptual
mechanisms to provide information to
our brains to guide current or future
behavior
• Notice there’s no mention of
consciousness
Perception and Cognition
• We have elaborate perceptual
mechanisms to provide information to
our brains to guide current or future
behavior
• Notice there’s no mention of
consciousness
• Lot’s of information gets processed and
used by your brain without you noticing
Perception and Cognition
• We have elaborate perceptual
mechanisms to provide information to
our brains to guide current or future
behavior
• Notice there’s no mention of
consciousness
• Lot’s of information gets processed and
used by your brain without you noticing
• Consider some examples
Blindsight and the Dorsal
Stream
• Lesions (usually due to
stroke) in primary visual
cortex cause a region of
blindness called a scotoma
• Identified using perimetry
X
Blindsight and the Dorsal
Stream
• Patients with lesions to primary visual
cortex occasionally retain some visual
abilities:
– better than chance performance on forcedchoice discrimination tasks
– spatial navigation and coordination (i.e.
avoid obstacles, interact with environment)
Blindsight and the Dorsal
Stream
• Patients with lesions to primary visual
cortex occasionally retain some visual
abilities:
– better than chance performance on forcedchoice discrimination tasks
– spatial navigation and coordination (i.e.
avoid obstacles, interact with environment)
• Thought to be because of other “backdoor”
pathways that send signals to the Dorsal
Stream, A.K.A the “Where and How Pathway”
Blindsight and the Dorsal
Stream
• The Dorsal Stream is thought to mediate
much spatial processing and interaction with
the environment
“WHERE”
“WHAT”
Blindsight and the Dorsal
Stream
• The Dorsal Stream is thought to mediate
much spatial processing and interaction with
the environment
• But the neural activity in these structures
does not (is not alone sufficient to) enter into
consciousness
Object Substitution Masking
• Masking occurs when one stimulus impairs
perception of a nearby stimulus
• In special cases the stimuli don’t have to overlap in
space or time!?
• Object substitution masking occurs when attention
cannot select a target object before it vanishes
…AND…
• A mask is visible at the target location after the target
has vanished
Object Substitution Masking
Object Substitution Masking
• Surprisingly, some visual information survives
masking
• Subjects are accurate at reaching to grasp a
masked shape even though they can’t
consciously see it
Masked Priming
• Surprisingly even the meaning of visual
information can survive some kinds of
masking
Masked Priming
S PAM
TIME
Masked Priming
XXXXX
S PAM
TIME
Masked Priming
SP__
XXXXX
S PAM
TIME
Masked Priming
• Subject must complete the stem to
make any word other than the word that
was masked
Masked Priming
• Subject must complete the stem to
make any word other than the word that
was masked
• Subjects are more likely to use masked
word…indicates subconscious influence
on behavior
The Hard Problem Returns
• MYSTERY: what is special about
neural activity that leads to awareness ?
NOBODY KNOWS !