Transcript 2320Lecture24

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)
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)
– What are some examples of Long-Term
Memories?
Some Distinctions in LTM
• Endel Tulving: There are two broad
categories of information that are
represented in LTM • Examples:
–
–
–
–
–
What did you eat for breakfast?
What is the capital of Canada
Where were you when…
Are maple trees deciduous?
Riding a bike !?
Some Distinctions in LTM
• Endel Tulving: There are two broad
categories of information that are
represented in LTM • 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
• Endel Tulving: There are two broad
categories of information that are
represented in LTM • Semantic Memory: memory of facts,
knowledge of the world
• unconnected to an autobiographical event
• no temporal context
Some Distinctions in LTM
• A third category may be distinguished:
– Example: riding a bike, playing an instrument
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 fap)
and must respond “word” or “non-word”
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”
“palace”
Target
“gap”
“gap”
Response
fast
slow
Semantic Memory
• Structure of encoding is associative
– Evidence: Semantic Priming in a LexicalDecision Task
– 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
Semantic Memory
• Structure of encoding is associative
– Example: Accessing a memory that is “on the
tip of your tongue”
• recalling a movie you wanted to rent
• each recalled piece of knowledge “activates” related
knowledge until the title is sufficiently activated
Semantic Memory
• Structure of encoding is associative
– This idea is formalized in so-called
“connectionist” networks
skiing
highschool
mockingbird
bird
canary
chicken
Mr. Cassella
To Kill A Mockingbird
racism
physics
Martin Luther King
When You Don’t Remember
• Two reasons why you don’t remember
semantic information:
When You Don’t Remember
• Two reasons why you don’t remember
semantic information:
• Unavailable
– It wasn’t successfully encoded - something
when wrong while you were studying
When You Don’t Remember
• Two reasons why you don’t remember
semantic information:
• Unavailable
– It wasn’t successfully encoded - something
when wrong while you were studying
• Inaccessible
– memory is stored but cannot be retrieved,
perhaps because appropriate connections aren’t
being made
Recalling Memories
• Memory is affected by the nature of your
engagement with the information
• Levels-of-Processing Theory
Recalling Memories
• 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 (surface processing)
•repeating words
• putting words into a sentence (deep processing)
Recall is tested some time later.
Recalling Memories
• 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 Memories
• 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
Recalling Memories
• context is critical!
– location, physiological state, etc. affect ability
to recall
– e.g. lists of words are recalled better when
recalled where they were first learned
• Similarities in context (especially smell) can
trigger vivid recollections
Recalling Episodic Memory
• Recall is a generative process rather than
simply calling up stored data
Recalling Episodic Memory
• Recall is a generative process 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
• Misinformation Effect
• Interpretation:
– Episodic memory can be distorted by
subsequent information
– Memory might be directly altered - the
Changed-Trace Hypothesis
– A second competing memory could be created
by the question, which interferes with the initial
memory - the Multiple-Trace Hypothesis
Recalling Episodic Memory
• Memory for episodes in life can be illusory
Recalling Episodic Memory
• Memory for episodes in life can be illusory
• Consider this example:
– Subjects were given a list of words to remember via a
video tape of a man and a woman speaking the words
Recalling Episodic Memory
• Memory for episodes in life can be illusory
• Consider this example:
– Subjects were given a list of words to remember via a
video tape of a man and a woman speaking the words
– Then given a list of words, some but not all of which
had been studied, and asked to indicate which speaker
had said the word or indicate “not sure”
Recalling Episodic Memory
• Memory for episodes in life can be illusory
• Consider this example:
– Subjects were given a list of words to remember via a
video tape of a man and a woman speaking the words
– Then given a list of words, some but not all of which
had been studied, and asked to indicate which speaker
had said the word or indicate “not sure”
– 87% of the unstudied words were attributed to one of
the speakers !
Recalling Episodic Memory
• False Memories may arise when details of a
crime are in question as in eye-witness
testimony or repressed memories of abuse
during childhood
Implicit and Explicit Memory:
yet another distinction
• The successful recall of episodic memory
entails a conscious awareness for the
contents of the memory
Implicit and Explicit Memory:
yet another distinction
• The successful recall of episodic memory
entails a conscious awareness for the
contents of the memory
• Explicit Memory is any memory that is both
available and accessible by consciousness
Implicit and Explicit Memory:
yet another distinction
• Are all memories explicit? Is all
information stored in the brain subject to
conscious scrutiny?
Implicit and Explicit Memory:
yet another distinction
• 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:
yet another distinction
• 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
Next Time:
– Repressed Memories by Beth Loftus
– Tuesday - neuropsychology of LTM and
discussion of The Lost Mariner by Sacks