Memory 2

1
Memory 2
2
The Physiological Basis of Memory

• The cellular basis of memory is a long-lasting
  change in the efficacy of the synapse. This was
  shown by Eric Kandel, using a simple experimental
  model, the sea slug Aplysia. It has a protective
  reflex that is modified during learning.
• During learning the synapse to the left in the
  drawing becomes activated. This leads to an
  increased synthesis of cAMP and protein kinases
  in the target cell (center). The cell nucleus
  (above) will be affected by the protein kinase.
  The final result will be an increased synthesis
  of new proteins and a growth of the main synapse.
  In this way the synapse will become more
  efficient and be able to release more transmitter

3
The Physiological Basis of Memory

• Learning takes place in the synapse between
  sensory and motor nerve cells.
• A schematic wiring diagram is shown to the right.
  An increased release of transmitter each time the
  sensory neuron is activated leads to a stronger
  muscle activation.
• The learning process is mediated via
  phosphorylation, initially in the synapse
  resulting in short-term memory and later via
  changes in gene activation.
• This results in growth of the synapse and a
  long-lasting change of function. Therefore,
  synapses form the building blocks of memory.

4
Long Term Memory

• Performance on even the most basic task requires
  memory for events or information that occurred in
  the past.
• Long term memory is a concept that represents
  that vast amount of knowledge we have stored
  about the world.
• This includes procedural knowledge, such as how
  to ride a bicycle, general or semantic knowledge
  about how things occur (e.g. rain), and episodic
  knowledge about specific events that have
  happened to us directly (graduation).
• The capacity of long term memory is assumed to be
  huge to store all of the necessary knowledge.
• Many researchers believe that knowledge in LTM is
  permanent, although this has been questioned.

5
Evidence for Permanence Decay vs retrieval
Failure

• Evidence for the presence of memory that we may
  not currently be able to access comes from
  studies of implicit tests with normal populations
  and with amnesiacs.
• An implicit test of memory is one in which memory
  is tested for an event without the awareness of
  the test subject. This is contrasted with
  explicit tests of memory in which the subject is
  actively attempting to recall an event.
• Examples of explicit tests include recognition
  recall, examples of implicit tests include stem
  completion exemplar generation. Implicit tests
  are based on models of priming.
• Priming is a term that refers to the phenomenon,
  that once you have been exposed to a stimulus
  once you will respond to the same stimulus faster
  if you are exposed to it again.
• Implicit tests can clearly demonstrate that you
  have access to previous events that you may not
  consciously be able to recall. This implies that
  much of what we fail to access is due to
  retrieval failure.

6
Graf Schacter, 1985

• This famous study with Amnesiac patients
  demonstrated that implicit tests can tap into
  memory processes that the patient is unable to
  retrieve

7
Levels of Processing Theory

• Although research has shown that attention is
  critical for the encoding of memories, not all
  attention is the same.
• How people attend to a stimulus and what they
  focus on is critical in determining what will be
  remembered.
• One theory that addresses this concept is Craik
  Lockharts (1972) theory on Levels of Processing.
• The Levels of processing theory argues that the
  deeper one encodes information by focusing on
  different stimulus characteristics, the stronger
  the memory code and the more resistant it will be
  to forgetting.

8
Levels of Processing theory

• In dealing with verbal information the levels of
  processing theory argues that we encode
  information at three different levels,
  STRUCTURAL, phonemic, and semantic with
  corresponding deeper levels of processing.
• However, studies have also shown that
  non-semantic information can be retained as long
  as semantic information (Stein, 1978). If this is
  the case then it casts doubt on the depth of
  processing hypothesis.

9
Elaboration Hypothesis Craik Tulving, 1975

• The deeper level of encoding occurs because of
  the increasingly elaborate nature of the
  processing.
• Elaboration by definition is linking a stimulus
  to other levels of information at the time of
  encoding.

10
More information about Elaboration

• Congruity effect-The congruity effect occurs when
  semantic orienting questions that are true,
  produce better recall, than semantic orienting
  questions that are false.
• E.g. The bird flew into the tree-Congruent
• The dog flew into the tree-Incongruent
• The Congruent condition will produce better
  retention for the sentence.

11
Organization

• Another important encoding process is
  organization.
• Organization is the process of grouping discrete
  items into larger units based on relationships
  among the items
• Whereas elaboration refers to the relationship
  among material to be remembered and material that
  will not be remembered, organization refers to
  relationships among the material to be remembered
  (e.g. duck, robin, sparrow are all forms of
  birds).
• Elaboration seems to emphasize distinctiveness,
  organization emphasizes similarities
• This effect occurs with both oblivious
  information but also with subjective information
  (e.g. information that is not obliviously
  related)
• Much of this seems to be based on context, that
  is, the situation the information is presented
  in.
• Organization also occurs for perceptual
  information

12
Encoding Parameters

• Information that is personally relevant, that is,
  has meaning for you will be remembered better
  than information that is non-specific to you.
• Information that is generated individually by a
  subject will be remembered better than
  information that is just presented.
• Information will be recalled better when you
  attempt to recall it in the same place that you
  encoded it (encoding specificity effect).
• Flashbulb memories (e.g. memories associated with
  strong emotion that seem to persist vividly over
  time) are not actually impervious to change or
  forgetting over time, they are however highly
  resistant to change decay because of the strong
  nature of encoding that occurs during a traumatic
  event (e.g. where you were on 9/11).

13
Visual Imagery Elaboration

• Do we store actual images of the world (e.g.
  analog images) or do we store representations
• There is good evidence to suggest that we do
  store visual codes with specific representations
  of the world.
• When we create a visual code in order to
  elaborate on information (e.g. picturing an image
  of a rabbit when we are asked to remember the
  item rabbit retention is superior.
• This effect led to the proposal of dual code
  theory
• Again this is probably due to linking a stimulus
  to other levels of information at the time of
  encoding.
• The additional stimulus cues enhance memory
  Retrieval!

14
Dual Code Theory

• This Study by Paivio, Smythe, and Yuille (1968)
  illustrates the benefits of elaboration at the
  time of encoding. Adding examples of visual
  imagery to words increases retention of items.
• This probably occurs because it provides a dual
  memory code.
• Dual-Coding Theory states that memory is
  enhanced by forming semantic and visual codes at
  encoding since either can lead to recall

15
Retrieval Processes

• Recovering Information from Long Term Memory

16
Retrieval from LTM

• For memory to be of use to us we must be able to
  retrieve it.
• In order to retrieve information we must be able
  to use a cue, that is some type of information
  must be available to delineate the specific event
  from all others stored in LTM.
• The retrieval process in dependent on cues
• Two major theories of cue effectiveness have been
  proposed, cue associative strength of the cue,
  and encoding specificity hypothesis

17
Associative Strength Theory of Cue Effectiveness

• Associative strength theory proposes that if a
  cue occurs frequently, it will be effective in
  retrieving a memory.
• Strongly associated cues produce better memory
  than do weakly associated cues (this information
  is based on studies of free association).
• Bird-Feathers Cat-Hair
• Bird-hair
• Associative strength theories work on the
  assumption that the memory structure consists of
  all items being interrelated in memory
• Retrieval begins with activation of the
  representation of the cue, and activation is the
  process of transferring information from LTM to
  STM.
• Spreading activation occurs when the cue that is
  activated also activates related concepts

18
Connectionist Models of Memory

• Not all information belongs to the same
  categories, but often times information is
  related in meaning to other pieces of
  information.
• A semantic network is a model of how items are
  represented in long term memory
• Theories of Parallel Distributed Processing
  propose that cognitive processes depend on
  patterns of activation in highly related and
  interconnected computational networks that
  represent neural networks

19
Encoding Specificity Hypothesis of Cue
Effectiveness

• Every events that ever occurs represents a unique
  combination of characteristics in terms of the
  stimulus cues that are present.
• Therefore, effective retrieval cues for memory
  are those that were specifically present at the
  time of encoding, this concept is referred to as
  encoding specificity
• This means that you will be able to retrieve
  information more effectively if you are in the
  same situation in which you encoded it, or if the
  original stimulus cues present at the time of
  encoding are present (e.g. taking a test in the
  same room in which you studied for it).
• Encoding specificity does not apply to general
  semantic knowledge that occurs frequently, but to
  specific events.
• It seems organization of information at encoding
  produces the general information being described
  in the retrieval process, but distinctive
  information is necessary to retrieve specific
  events.

20
General Knowledge Specific Memory

• The difference between encoding specificity and
  cue distinctiveness demonstrates that retrieval
  of information is different depending on the
  situation(e.g. specific information or general
  knowledge)
• This suggests the possibility of different and
  distinct LTM systems.
• Tulving (1985) has suggested a useful
  classification system
• Procedural memory-refers to memory processes that
  are required to retrieve information underlying
  skilled performance (e.g. bicycling or walking).
  This type of information retrieval is automatic,
  and is characterized by absence of thought
• Semantic Memory-this type of knowledge is general
  information about the world, it is context
  independent, and does not refer to a specific
  event. Accompanied by a feeling of Knowing
• Episodic Memory-is the system that represents
  specific events, the cues to retrieve them must
  have been part of the original episode, it is
  very context dependant, and is accompanied by a
  conscious feeling of remembering.

21
Evidence for Multiple LTM Systems

• Different characteristics seem to represent the
  different systems (associative strength vs.
  encoding specificity).
• Studies of Amnesiacs (retrograde amnesia) often
  demonstrate selective impairment of memory
• That is they demonstrate impaired episodic
  knowledge but intact semantic knowledge (e.g.
  assessed performance on indirect tasks like
  solving word puzzles is spared but performance on
  direct tests like recognition is impaired).
• PET and SPECT studies have demonstrated that
  performance on incidental encoding and retrieval
  tasks seems to activate the left prefrontal
  cortex, while episodic retrieval seems to
  activate the right pre-frontal cortex.
• Performance memory or procedural memory also
  seems to be impaired in some types of
  neurological patients (e.g. Parkinson's and
  Huntington's patients) while semantic and
  episodic retrieval seems to be spared.
• Again this is supported by PET studies showing
  different areas of activation in the brain during
  procedural tasks.

22
Direct or Indirect retrieval?
Memory Item
Correct vs. Incorrect
Recall
Cue
Memory
Memory Item
Recall
Use Memory Cue

• A single process view suggests that we use an
  encoded cue to directly retrieve a memory item,
  encoding specificity supports this view as do
  studies using recognition test procedures.
• The generation-recognition view is an alternative
  view of memory retrieval that suggests that
  recall of an item requires that we retrieve an
  item, and then decide if it is correct or
  incorrect prior to recall. Studies using recall
  test procedures support this view.
• An interesting note is that high frequency words
  are recalled better, but low frequency words are
  recognized better, this makes sense if you
  believe that recall requires generation of a word
  while recognition only requires discrimination of
  a word (thus support for the generation
  hypothesis)

23
Implicit vs. Explicit Memory Tests

• Explicit memory tests (or direct tests) include
  the two types of processes mentioned in the
  previous slide, recognition recall.
• They are considered direct tests because they
  specifically direct the test subject to some
  piece of information to be retrieved.
• Implicit memory tests (or indirect tests) include
  tests like completion of a word fragment, or the
  generation of a category exemplar (see below)
• HOR_ _ or MOU _ _ Cat as the example of the
  category Animal
• Indirect tests attempt to demonstrate that some
  past experience like exposure to a certain word
  will influence the production of a stem or
  category.
• Indirect tests do not specifically direct you to
  a previous experience, they attempt to show an
  influence of Priming
• indirect tests and direct tests can be
  dissociated which has again provided evidence of
  different memory systems and different retrieval
  processes

24
Dissociations on Explicit vs. Implicit Tests

• Dissociations by definition mean that a variable
  has a different effect on performance depending
  on the type of test used to measure it (like
  amnesia).
• Numerous other factors that produce dissociation
  also have been studied, (for example semantic
  orienting tasks and read vs. generate tasks
  produce large effects on direct tests but little
  effects on indirect tests).

25
Dissociations on Explicit vs. Implicit Tests

• In general, The Memory Systems Explanation (e.g.
  Tulvings proposal of Episodic, semantic,
  Procedural memory) assumes that direct tests draw
  on Episodic Memory, and indirect tests draw on
  Semantic Memory.
• Since the different systems operate according to
  different principals it is not surprising that a
  variable can have very different effects on the
  different tests.
• Direct tests are also subject to encoding
  specificity, that is Indirect tests are governed
  by associative strength, since they operate from
  semantic memory.

26
A Different way to think about implicit memory
tests Conceptually Driven Vs. Perceptually
Driven Tests

• Perhaps a better way to think about memory tests
  has been proposed by the Transfer Appropriate
  Processing Theory.
• A memory test the re-engages the same type of
  processing used at encoding will work better than
  one that types to tap the opposite type of
  processing
• Reading a word at study is thought to rely on the
  physical features, while generating a word is
  thought to rely on its semantic features.
• Therefore a memory test like stem completion (a
  perceptual test) would work better on a person
  who read a work compared to a person who
  generated a word

27
Dividing Attention at Study an interesting way
to determine what types of processing is at work

• If you divide a subjects attention at study
  between two tasks, you are going to interfere
  with semantic (associative processing), but this
  should not interfere with automatic perceptual
  processing.

28
Retrieval Failure Another way of Examining
Memory Processes

• Decay theory-Suggests that memory weakens or is
  lost over time. However studies of implicit
  memory, and some physiological studies have cast
  doubt on the decay theory.
• Interference Theory-information is unavailable at
  recall because competing information cause
  retrieval failure

29
The Search for The Physiological Basis of Memory

• The slide above shows Wilder Penefields attempt
  to localize memory by stimulating areas of an
  awake patients cortex during a surgical
  procedure for epilepsy.
• Penefields patients reported vivid memories in
  response to stimulation by an electrical probe.
  Penefield was only able to obtain these results
  when he stimulated areas of the temporal lobe so
  he concluded that was the area of storage for
  memories.
• Later researchers have been critical of
  Penefields methods and at this time it does not
  appear that memory is localized to the temporal
  lobe

30
Interference

• Interference can come in two forms, retroactive,
  and proactive and may be responsible for
  retrieval failure

31
Physiological Evidence for Interference Theory
Types of Amnesia

• There are two major groups of amnesiacs
  classified on the basis of which type of memory
  is impaired. Memory before the accident, or
  memory after the accident

32
6 Major systems in memory

• Perceptual (e.g. sensory register)
• STM
• LTM
• -Procedural
• -Episodic
• -Semantic
• Priming is a system that resembles perceptual
  memory but is not, resembles semantic memory but
  is not. Priming is a form of implicit memory, in
  that it occurs automatically and is non-conscious

E
STM
S
P
P
Priming
33
Cognition, Emotion, Memory
34
Emotion

• Emotion-is usually referred to as positive or
  negative feelings that are produced by a
  particular situation.
• Emotions are patterns of physiological responses
  and species typical behaviors linked together, In
  humans these responses are accompanied by
  feelings.
• Most of us use the term emotion to refer to
  feelings, and not the behaviors that accompany
  the feelings.
• However, it is the behaviors, and not the
  feelings, that have consequences for our survival
  and reproduction.
• Thus the argument could be made that the useful
  purposes served by emotional behavior, are what
  guided the evolution of the brain, the feelings
  that accompany these behaviors came later in the
  evolutionary game

35
Classic theories of Emotion

• Stanley Schacter was an influential psychologist
  who developed an important theory of Cognition,
  emotion, Memory

36
Schacter Singer
37
The Physiology of Emotion

• There are three components to an emotion
  response, 1) a behavioral component, 2) an
  autonomic component, and 3) a hormonal component
• For example when a dog defends its territory
  against another dog, it first postures, growls,
  and shows its teeth. If the intruder does not
  leave, the dog attacks and the sympathetic branch
  of the nervous system increases activity and the
  parasympathetic branch reduces activity allowing
  for an increase in blood flow and respiration.
  Finally hormonal responses reinforce the
  autonomic responses (e.g. the adrenal medulla
  secretes epinephrine and norepinephrine which
  further increase blood flow stimulate the
  production of glucose).
• The overt behaviors, the autonomic responses, and
  the hormonal responses are all controlled by
  separate neural systems, however the integration
  of these responses appears to be controlled by
  the amygdala.

38
The Physiology of Emotion

• The amygdala is located in the temporal lobe, and
  seems to plays a special role in physiological
  arousal and behavioral reactions to objects
  situations that have special biological
  significance (e.g. those that warn of pain or
  signify the presence of food, water, or other
  important biological stimuli).
• The amygdala has also been associated with memory
  for emotional events.
• The central nucleus of the amygdala receives all
  forms of sensory information, relayed down from
  the the primary sensory cortex and association
  cortex, and up from the thalamus via the
  basolateral group.
• The area also projects to the hippocampus.
• Damage to the amygdala leads to reduces or
  abolishes a wide range of emotional responses

39
The Physiology of Emotion

• The orbitofrontal cortex is located just at the
  base of the frontal lobes, just above the eye
  orbits.
• This area receives indirect input from the
  amygdala and direct input from the thalamus and
  and temporal cortex.
• It has been shown to play an important role in
  the control of emotional behavior, damage to this
  area reduces peoples inhibitions and self concern
  so that they become less sensitive to the
  consequences of their actions.
• Although they remain responsive to pain, the pain
  no longer produces an emotional reaction.
• This finding has lead to the use of the
  pre-frontal lobotomy as a tool for controlling
  emotional reactivity

40
Phineas Gage An early neuropsychological Case
Study in Cognition Emotion

• The famous case of Phineas Gage, and the tramatic
  destruction of the orbitofrontal cortex.

41
Emotion, Cognition Memory

• Research on the relationship between emotional
  states and cognitive processes has shown a
  significant increase in the last 25 years
• On reason for the recent interest in emotions, is
  that it has become apparent that emotion (or
  affective) states, can very much influence
  cognitive processes.
• An additional reason for the increase in studies
  examining emotion cognition is that research
  methods for inducing temporary emotional states
  (e.g. hypnosis or verbal induction) have been
  introduced, which allows emotion as a variable to
  be introduced.
• Finally the last 25 years has seen an increase in
  studies assessing normal moods, rather than just
  examining disordered moods.
• Due to some of the major research finding on mood
  influenced memory, many cognitive psychologists
  have now become convinced that any model of
  memory cognition must account for the influence
  of affective states, such as stress anxiety,
  depression, and arousal.

42
Mood Congruent Memory

• Mood congruence refers to the finding that people
  are more likely to remember information that is
  congruent with the mood state they were in when
  they learned the material (Bower Monteiro,
  1981).
• Mood Congruent States-A mood congruent effect
  occurs when material learned in a particular mood
  is recalled when a person is tested under the
  same state.
• This effect probably occurs because the emotion
  gives additional recall cues to guide the gist or
  theme of the information.

43
Mood effects on Encoding

• Encoding seems to be best when an individual is
  in a neutral mood.
• Subjects in sad moods also perform poorer on
  elaboration tests.