model of memory

Model of Memory

Turning now to Long-Term Memory

Sensory Signals

Sensory Memory

Short-Term Memory

Long-Term Memory

ATTENTION

REHEARSAL

RETRIEVAL

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

• 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


• 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


• There is a third category:

• 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 Lexical-

Decision Task

• Priming: prior exposure to some stimulus modifies subsequent processing of a target

Semantic Memory


Decision 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


Decision Task

• manipulation: prime can be either related or unrelated to the target word

Semantic Memory


Decision Task

• result: words are identified faster when preceded by a semantically related prime

Prime + Target = Response“space” “gap” fast“truck” “gap” slow

Semantic Memory


Decision 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

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


• Memory is affected by the nature of your engagement with the information

• Levels-of-Processing Theory



• Levels-of-Processing Theory– Consider this experiment:

ListCATpiePILLOWTREE

Method of Learning• stating capitals or lower-case• repeating words• putting words into a sentence

Recall is tested some time later.



• Levels-of-Processing Theory– Consider this experiment:

Result:• Best recall with “deep”

processing• Worst recall with “surface”

processing

ListCATpiePILLOWTREE



• 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


• context is critical!– location, physiological state, etc. affect

ability to recall and your confidence that you recalled correctly

– e.g. lists of words are recalled better when recalled where they were first learned

When You Don’t Remember

• Two reasons why you don’t remember:


• Two reasons why you don’t remember:• Unavailable

– It wasn’t successfully encoded - something went wrong while you were studying


• 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: yet another distinction

• Are all memories explicit? Is all information stored in the brain subject to conscious scrutiny?


• 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


• 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


• 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


• 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


• 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


• 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


• Recall is a generative processes rather than simply calling up stored data


• 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


• Misinformation Effect - exposure to information subsequent to storage of memory can alter the contents of the 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





– Different subjects were asked questions that differed in the “magnitude” of the final word

– The possible words were: Contacted, Hit, Bumped, Collided, and Smashed



– Average estimated velocity depended on the nature of the question


• Misinformation Effect • Interpretation:

– Episodic memory can be distorted by subsequent information


• 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



• 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


• False Memories may arise when details of a crime are in question as in eye-witness 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




• What does Loftus challenge?




• 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?


the derepression of memories?– reality of the memory is in question if it is recalled under

certain circumstances



certain circumstances• What is the course of events that Loftus finds

worrisome?



certain circumstances• What is the course of events that Loftus finds

worrisome?

Therapist or Popular Book suggests that patient consider possibility of abuse

Patient engages in intense effort to recall

An explicit episodic memory is achieved

This memory might be false!

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

model of memory

Documents

semantic priming

ltm semantic memory

lexicaldecision task

ltm episodic memory

recall episodic memorymemory

lexicaldecision task

procedural memory

memory of facts