Properties of STM
1. Short (scale of seconds)
2. Limited capacity
3. Attentive
–
–
–
Primacy
Recency
Interference (complex and specific)
A Modular Approach to STM
Central
Executive
Articulatory
Loop
Visuospatial
Sketchpad
Experiment 1 in the article by Lee Brooks
demonstrates a double dissociation between
Articulatory Loop and Visuospatial Sketchpad
Model of Memory
RETRIEVAL
Turning now to Long-Term Memory
ATTENTION
Sensory
Signals
Sensory
Memory
Short-Term
Memory
Long-Term
Memory
REHEARSAL
Long-Term Memory
• Characteristics (intuitive with some
introspection):
– Persists indefinitely (up to decades!)
– Requires no active process of rehearsal (at
least that we are conscious of)
Some Distinctions in LTM
Declarative
• Declarative memory is for the sort of information
that can become explicit – facts (semantic),
autobiographical events (episodic).
• The term explicit memory is often associated to
convey that such memories are accessible to
conscious awareness.
Some Distinctions in LTM
• Non-Declarative
• Non-declarative memory is for the sort of
information that is used without explicit awareness
– how to do an action (procedural)
• Implicit memory is when behaviour is influenced in
the absence of conscious memory.
Some Distinctions in LTM
Declarative Memory
• Episodic Memory: memory of an event
in your life
• autobiographical
• has a temporal context - something about time
is encoded along with the memory
Some Distinctions in LTM
Declarative Memory
• Semantic Memory: memory of facts,
knowledge of the world
• unconnected to an autobiographical event
• no temporal context
CHARACTERISTICS
EPISODIC
SEMANTIC
Likelihood of forgetting
High
Low
Usefulness
Low
High
Recollective experience
Present
Absent
Sensory component
Present
Absent
Presence of emotion
Present
Absent
Some Distinctions in LTM
• Procedural Memory: memory for actions
Semantic Memory
• Capacity is huge (unlimited?)
Semantic Memory
• Structure of encoding is associative
Semantic Memory
• Structure of encoding is associative
– Evidence: Semantic Priming in a LexicalDecision Task
• Priming: prior exposure to some stimulus
modifies subsequent processing of a target
Semantic Memory
• Structure of encoding is associative
– Evidence: Semantic Priming in a LexicalDecision Task
• Lexical Decision Task: Subject is shown a
target word or pronounceable non-word (eg.
gap or bap) and must respond “word” or “nonword”
Semantic Memory
• Structure of encoding is associative
– Evidence: Semantic Priming in a LexicalDecision Task
• manipulation: prime can be either related or
unrelated to the target word
Semantic Memory
• Structure of encoding is associative
– Evidence: Semantic Priming in a LexicalDecision Task
• result: words are identified faster when
preceded by a semantically related prime
Prime +
“space”
“truck”
Target =
“gap”
“gap”
Response
fast
slow
Semantic Memory
• Structure of encoding is associative
– Other evidence: memory can be triggered
by recalling related facts
Semantic Memory
• Structure of encoding is associative
– Interpretation:
• the representation of information in semantic
memory is associative:
• each fact or piece of knowledge is stored along
with its relationship to other stored information
• related items can activate each other which
facilitates recall
Episodic Memory
• Memory for an episode or event in your
own life
• Has temporal context (entails a sense of
duration and date)
• examples:
– recall breakfast
– what happened this weekend
Recalling Episodic Memory
• Recall is highly sensitive to context Similarities in context (especially smell)
can trigger vivid recollections
Recalling Episodic Memory
• Memory is affected by the nature of
your engagement with the information
• Levels-of-Processing Theory
Recalling Episodic Memory
• Memory is affected by the nature of
your engagement with the information
• Levels-of-Processing Theory
– Consider this experiment:
List
CAT
pie
PILLOW
TREE
Method of Learning
• stating capitals or lower-case
• repeating words
• putting words into a sentence
Recall is tested some time later.
Recalling Episodic Memory
• Memory is affected by the nature of
your engagement with the information
• Levels-of-Processing Theory
– Consider this experiment:
List
CAT
pie
PILLOW
TREE
Result:
•Best recall with “deep”
processing
•Worst recall with “surface”
processing
Recalling Episodic Memory
• Memory is affected by the nature of
your engagement with the information
• Interpretation:
– the successful use of memory depends on
the number of connections that are made
between related items and the degree to
which these are initially activated
Hypermnesia - S.
• “Photographic” extreme memory ability
(a mnemonist)
• Able to recall complex test stimuli
Hypermnesia - S.
• S. used two “strategies” or abilities
typical of mnemonists:
– Rich synesthesia-like quality to his
perception of stimuli - leads to stronger
associative links
Hypermnesia - S.
• S. used two “strategies” or abilities
typical of mnemonists:
– Rich synesthesia-like quality to his
perception of stimuli - leads to stronger
associative links
– Vivid and elaborate mental imagery of
things he should remember
Hypermnesia - S.
• “ Even numbers remind me of images.
Take the number 1. This is a proud,
well-built man; 2 is a high-spirited
woman; 3 a gloomy person (shy, I don’t
Know); 6 a man with a swollen foot...”
Luria, A.R. The mind of a mnemonist. 1968
Luria, A.R. The man with a shattered world. 1972
When You Don’t Remember
• Two reasons why you don’t remember:
When You Don’t Remember
• Two reasons why you don’t remember:
• Unavailable
– It wasn’t successfully encoded - something
went wrong while you were studying
When You Don’t Remember
• Two reasons why you don’t remember:
• Unavailable
– It wasn’t successfully encoded - something
went wrong while you were studying
• Inaccessible
– memory is stored but cannot be retrieved,
perhaps because appropriate connections
aren’t being made
Implicit and Explicit Memory
• Are all memories explicit? Is all
information stored in the brain subject to
conscious scrutiny?
Implicit and Explicit Memory
• Are all memories explicit? Is all
information stored in the brain subject to
conscious scrutiny?
• Implicit Memory refers to encoded
memories that are not part of the
“contents” of awareness
Implicit and Explicit Memory
• How can we know whether memory is
stored/recalled implicitly or explicitly?
Implicit Memory
• Consider the following distinction in recalling
items from a list of words:
Implicit Memory
• Consider the following distinction in recalling
items from a list of words:
• Free Recall - subjects can be asked to simply
recall and report as many items as possible these items are accessible as explicit memory
Implicit Memory
• Consider the following distinction in recalling
items from a list of words:
• Implicit Recall - subjects can be asked to
complete a word stem with any word that
comes to mind after reading a list of words
(no mention of testing memory!)
__ack
Implicit Memory
• Consider the following distinction in recalling
items from a list of words:
• Implicit Recall - subjects can be asked to
complete a word stem with any word that
comes to mind after reading a list of words
(no mention of testing memory!)
But how do you know that information is stored/recalled
implicitly? Couldn’t it be explicit?
Implicit Memory
• Consider the following distinction in recalling
items from a list of words:
• Twist - require subject to complete stem with
a word that wasn’t on the list - if a word from
the list is used preferentially, it was
remembered implicitly
Implicit Memory
Consider the implications regarding the
nature of consciousness and the
connection between neural activity and
awareness
Implicit Memory
Consider the implications regarding the
nature of consciousness and the
connection between neural activity and
awareness
Not all of the activity in your brain generates
experience - some is “sub”conscious or
non-conscious
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
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 ______”
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
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
• Memory for episodes in life can be
illusory
Recalling Episodic Memory
• Memory for episodes in life can be
illusory
• Consider the example in Loftus’ article:
– participant was induced to have an episodic
memory of being lost in a mall
Recalling Episodic Memory
• Memory for episodes in life can be
illusory
• Consider the example in Loftus’ article:
– participant was induced to have an episodic
memory of being lost in a mall
– Even when told the memory is a false one, the
participant had difficulty recognizing it as an
invalid memory
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
Repressed Memories
Elizabeth Loftus
“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