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Title: Presentazione di PowerPoint


1
Outline
  • Definitions
  • Abnormal memory amnesics and mnemonists
  • How do we forget?
  • Memory stores
  • Memory tasks
  • Working memory
  • Levels of processing
  • Semantic and episodic memory
  • Cognitive neurosciences notes
  • Information encoding
  • Oblivion
  • Consolidation
  • Retrieval
  • Constructive theories

2
Naïve definitions
  • Main Entry memory
  • the power or process of reproducing or recalling
    what has been learned and retained especially
    through nonconscious associative mechanisms
    conscious or unconscious evocation of things past
  • the process of reproducing or recalling what has
    been learned as manifested in some special way or
    as associated with some bodily process visual
    memory muscular memory
  • persistent modification of structure or of
    behavior resulting from an organism's activity or
    from its passively acquired experience
  • the totality of what has been learned and
    retained especially as evidenced by recall and
    recognition drew on his memory to supply the
    needed names even birds and animals have an
    ancestral memory
  • the function of memory regarded as a compartment
    or chamber in which images, perceptions, or
    learning are stored filling their memory with a
    lumber of words
  • a particular act of recalling something learned
    or experienced the fact or a condition of
    recalling REMEMBRANCE, RECOLLECTION, RECALL
  • an image, impression, or other mental trace of
    someone or something known or experienced the
    content of something remembered
  • a component in an electronic computing machine
    (as a computer) in which information (as data or
    program instructions) may be inserted and stored
    and from which it may be extracted when wanted a
    device external to a computer for the insertion,
    storage, and extraction of information
  • a capacity for showing effects recognized as the
    result of past treatment used especially of
    materials the wire begins to turn in the other
    direction corresponding to the first twisting
    a capacity for returning to a former condition ..

(adapted from Merriam-Webster Unabridged
Dictionary)
3
Experts definitions
  • Memory is the means by which we retain and draw
    our past experiences to use this information in
    the present (Tulving)
  • As a process, memory refers to the dynamic
    mechanisms associated with retaining and
    retrieving information about past experience
    (Crowder, 1976)

4
Abnormal memories
  • The study of individuals with abnormal memories
    is fundamental for the scientific understanding
    of memory.
  • Individuals with deficitary memory are defined
    amnesic. Individuals with exceptional memory are
    defined mnemonists.

Amnesia
  • The most famous case of amnesia is H.M., who
    had neurosurgery with removal of epileptic foci
    at age 29.
  • The operation caused a specific pattern H.M.
    could not recall any event occurred after the
    event, whereas the preceding events were left
    intact.
  • This form of amnesia in which the memory of
    events following the cause of the amnesia is
    selectively compromised is called anterograde
    amnesia.
  • This impairment leaves the patient in un
    permanent present, with a very short conciousness
    window.
  • The functional damage seems to be due to an
    interruption in the flowing of information from
    the Short- to the Long-Term Memory.

5
Amnesia
  • Another patient, reported by Russel e Nathan
    (1946) underwent to a contusion that caused a
    selective loss of a slice of memories from 1922
    to the traumatic event. Previous memories were
    preserved. Moreover, the functional recovery,
    which eventually was complete, advanced from the
    oldest memories to those closer to the trauma.
  • This and other similar phenomena led to thinking
    that LTM strengthen on the base of a temporal
    gradient. Older memories would have longer time
    for consolidation than newer ones, resulting
    stronger.
  • This property of memory can be observed in the
    tendency of eldery people of talking more of
    their remote experiences than of newer ones.

6
The mnemonists
  • The amount of information that is learned and
    can be recalled is highly variable among
    individuals. If we count how many telephone
    numbers we know by heart, we would reveal
    enormous differences.
  • Although memory is normally variable, there are
    exceptional cases in which the capacity of
    learning and recalling is enormously higher than
    for normal subjects.
  • Mr Shereshevsky went to Dr. Luria office, in
    Russia, asking to be tested for his memory. The
    result was sensational
  • Shereshevsky could recall lists of numbers that
    he had memorized decades earlier, and was
    actually unable to forget the lists he had
    memorized while perfoming as a mnemonist. He
    could memorize nonsense syllables, a challenge
    specifically designed to thwart mnemonic
    associations. S experienced synesthesia,
    responding to stimulation of one sense with a
    perception in one or more different senses. For
    example, he could see sounds and feel their taste
    and texture. His remarkable abilities were
    somewhat disabling. He was not able to read
    poetry or fiction easily, as each word or phrase
    would blossom into an intense visualization that
    might be contradicted by the next one...
    Shereshevsky's pathological memory interfered
    with his ability to hold a regular job, enjoy
    literature, or even seemingly to think in the
    abstract without being distracted by sensory
    association.".

7
The mnemonists
  • The secret of mnemonists seems to lay in their
    synesthesia, a phenomenon for which a sensation
    produces a secondary subjective sensation. This
    allowed Mr S to form complex cross-modal
    associations between words and mental images.
  • Other mnemonists base their exceptional skills
    upon different, more symbolic cues, like
    associating a list of numbers with dates or sport
    events.
  • Independently on the mental representation,
    based on symbols or on mental images, it seems
    that the base for the mnemonists skills is a
    supra-normal ability of forming associations of
    some kind.

8
General Intro
  • Memory is a fundamental cognitive skill for the
    cognitive and psychological integrity of
    individuals.
  • It has different manifestations, and its basic
    processes can be either automatic and effortless
    or require active effort.
  • It is currently thought the memory is diveded in
    sub-abilities each based on different,
    independent systems.
  • The cognitive approach to memory makes the
    fundamental division into three basic processes
    encoding, storage and retrieval.
  • Encoding has, in turn, two stages acquisition e
    consolidation. Aquisition puts the incoming data
    in a sensory buffer. Consolidation creates a
    stable representation over time.
  • Storage, which is the result of acquisition and
    consolidation, creates and holds data in
    permanent records.
  • Retrieval uses stored information to create a
    conscious representation or to execute some
    active behavior previously learned, like a motor
    act.

9
Memory stores
  • The complexity of human memory is such that it
    requires different levels of categorization.
  • The main categorization divides the memory stores
    according to the duration of the trace by
    postulating three stores Sensory Memory (SM),
    Short Term Memory (STM) and Long Term Memory
    (LTM).
  • SM (also called iconic, echoic, etc. according
    to the specific sensory modality) is active from
    the sensory event until few seconds from it.
  • STM, or immediat memory, holds material within a
    period from few seconds until some minutes after
    its occurence.
  • LTM is measured in terms of minutes, hours and
    days, although it can be life lasting.

10
Memory stores
  • The three stores were formalized firstly by
    Atkinson e Shiffrin (1968).
  • They proposed the so-called modal model of
    memory, in which the transfer of information from
    SM to STM is based upon attentional selection,
    while that from STM to LTM is based upon reharsal.

11
Sensory Memory
  • The classical task to probe SM consists in the
    rapid presentation of letter matrices. Subjects
    are asked to recall the letters presented at
    various intervals.
  • The matrix is displayed very briefly (50 ms) to
    avoid scanning eye movements.

H Q Z P K R Z E M B A F
  • From this study the average span of iconic
    memory ranged around 4 elements.
  • However, subjects often reported they saw
    clearly all the letter presented, but the recall
    of the first letters would somehow mask that of
    the following letters.

12
Sensory Memory
  • G. Sperling (1960) modified this task asking the
    observers a partial recall.
  • In this version, the matrix was presented
    entirely, but the subjects were requested to
    recall only one line signaled after the matrix
    disappearence. The signal of the line to be
    reported was presented at different times, -0.1
    to 1 second from the matrix disappearence. This
    does eliminate the interference in recalling a
    long list of letters.

S Q W P H S L E W R C O
Signal at various intervals
  • Since subjects could not predict what line had
    to be reported, the actual span corresponded to
    the number of letters reported multiplied by the
    number of lines (3).

13
Sensory Memory
  • Using this technique the measured span grew from
    4 to about 9 items when the cue was synchronous
    or appeared immediately after the matrix. For
    longer lags it decayed at 4-5 items.
  • This study has shown the existance of a sensory
    buffer of very short duration (lt 1 second).

14
Short Term Memory
  • Write down the name of the scientist who
    discovered the properties of SM

George Sperling
15
Short Term Memory
  • While SM is difficult to experience consciously
    (information is seldom available for only 50 ms,
    and often new information overlaps to impede its
    recall), the properties of STM are often evident
    and subjects to continuous -negative-
    verifications.
  • In a famous study by G. Miller (1956) it was
    suggested that the amount of items that could be
    held in STM was 72.
  • The problem arises when a definition of item has
    to be drawn in fact, if we chunk a list of 21
    numbers in groups of three items, we will
    probably recall the whole list without much
    troubles!
  • This is indeed a mnemonic (i.e. a memory
    strategy) known as chunking.

16
Long Term Memory
  • LTM constitutes the deposit of informations,
    notions, happenings that form the base of our
    conscious knowledge throughout life and that are
    used for contingent behaviors.
  • On these bases, LTM seems to be unlimited and
    permanent, making the task of defining its last
    and span virtually impossible.
  • While he was mapping the somatosensory cortex by
    stimulating the brain of epileptic patients,
    Penfield (1969) noticed the side effect that
    subjects recalled events of their first childhood
    that had been apparently lost. This was
    interpreted as a sign of the fact that LTMs are
    permanent.
  • LTM has been divided in two sub-types (Tulving,
    1990) esplicit an implicit memory. To express a
    similar concept, Squire (1987) used the terms
    declarative and non declarative memory.
  • Esplicit, or declarative memory is the conscious
    content of our long-term knowledge. Its our base
    of knowledge.
  • Implicit, or non-declarative memory is all that
    is accessed in an unaware fashion, like the
    procedural knowledges (riding a bycicle), the
    priming and all those behaviors derived from
    conditioning, abituation or sensitization.

17
Memory tasks
  • Respecting the complexity of its object, there
    are a variety of tasks to study the properties of
    memory.
  • A first category distinguishes between recall
    and recognition tasks.
  • In the first case its asked to recover
    information from memory, in the second to select
    or identify some elements previously learned.
  • To mention from the recall tasks are
  • serial recall tasks, where items must be
    recalled in the exact order they were learned,
  • free recall tasks, without any order constraint,
    and
  • facilitated recall tasks, in which items are
    learned in couples, but only one member of the
    couple is presented during the test and the
    paired element must be recalled.
  • Among the recognition tasks are the familiar
    true-false tests and multiple choice tests.
  • Usually recognition is better than recall.

18
Memory tasks
  • A second distinction is for implicit vs esplicit
    memory tests.
  • Recall and recognition tests are directed to the
    esplicit memory, in that they imply conscious
    recovery of information.
  • In the implicit memory tests is assessed to what
    extent knowledge or facts to which we got exposed
    influence the outcome of target tests or
    behaviors.
  • A typical implicit memory test is word
    completion ca _ _ _ _ _ _
    fa _ _ _ _ _ _
  • The information preceding the test can be
    manipulated in controlled lab conditions. Under
    this optimal setting, the words used most
    frequently to complete are those seen in the
    implicit learning session. This occurs even to
    amnesic patients. This phenomenon is known as
    priming.
  • Category, familiar

19
Memory tasks
  • A third category is aimed to test procedural
    memory, that is suited for tasks such as motor
    behaviors.
  • Among the procedural memory tests we can
    mention
  • solving puzzles
  • reading mirror writing
  • walking with prisms
  • In all these tests, the amnesic skills are
    tipically well preserved.

20
Working memory
  • The main alternative to the modal model
    (Atkinson and Shiffrin) of memory, which
    distinguishes 3 main temporal stages, is one that
    attributes a key role to the working memory.
  • Working memory is similar to the STM, but with
    an active role for the information processing.
  • Rather than a simple container of information
    for short time, working memory would have an
    active role in
  • selecting and moving material from/to the LTM
    module
  • selecting and integrating sensory data
  • operating a meta-integration of all the
    information needed for the behavior in progress
  • The temporal span and the capacity of this
    module are both limited.

21
Levels Of Processing
  • A completely different approach is that of
    Levels Of Processing (LOP) by Craik and Lockart
    (1972).
  • Rather than relying on discrete stores, memory
    would work in a continuum based on the depth of
    encoding.
  • The LOPs would then be infinite as the point in
    a line.
  • The deeper the LOP, the likelier the encoding.
  • Generally, tre levels are distinguished
    physical, acustical and semantic.
  • The key experiments for the theory asked
    specific questions on words presented to the
    subjects. The questions were formulated to
    activate selectively one of the three levels.

TABLE is it capital or not? PHYSICAL
LEVEL Nature does it rhyme with
future? ACOUSTIC LEVEL sunflower is it a
plant? SEMANTIC LEVEL
22
Levels Of Processing
  • The results showed that the recall improved as a
    function of the level.
  • Further support to the LOP came from the studies
    of Zinchenko (1962, 1981), who showed that the
    retrieval of semantically related words (dog
    animal) was better than for words that were
    concretely connected (dog leg), and the recall
    for these was in turn better than for unrelated
    words.
  • However, many critics were brought to the LOP
    approach
  • the definitions of the levels is loopy the depth
    of encoding is both the cause and the effect of
    memorization
  • in some cases the recall based on rhymes is
    better than for semantic contents.
  • The solution of this seem to lie in the
    relationship between the encoding of the material
    when it was learned and the level of recall
    required by the task.
  • In general, it seems that the use of different
    levels when recalling increases the chance of
    successful retrieval.

23
A synthetic view
  • Baddeley conciliates the two models by extending
    the LOP approach

visuo-spatial block Note stores mental
images for short times
phonologic- articulatory loop stores
briefly subvocalizzations for the verbal
comprehension and the acoustic reharsal
central executive coordinates attentional
activities and drives the responses
supplementary perceptive and cognitive systems
level of acoustic processing
the STM brain it manages its content by
moving it in and out the store
level of physical processing
24
Semantic and episodic memory
  • The patients of Penfield, after stimulation
    recalled particular facts or episodes, but never
    semantic concepts linked to specific events.
  • Tulving proposed a dissociation between a memory
    system devoted to specific episodes in a temporal
    location (e.g. what you had for lunch two days
    ago) and one storing semantic information,
    devoted to meanings and notions, without a
    precise temporal location (e.g. who studied SM,
    what is a mnemonist, etc.)
  • A number of neuropsychological evidence support
    this distinction. For example, lesions to the
    temporal lobe impair the faculty of recalling the
    when of particular events, but not their
    recognition.

25
Semantic memory concepts and schemas
  • Semantic memory would be based on concepts, that
    is ideas to which features are attributed and
    other ideas can be associated in networks. For
    example, a car has a cc, a color, a price, etc..
    Also, the idea of a car is easily associated with
    that of the highway, wheels, pollution, etc..
  • The schemas would be organizing structures for
    concepts based upon experience and culture.
  • Collins e Quillian proposed that semantic memory
    had a hierarchical structure.
  • The farther the two terms in the network, the
    slower the responses. For example, by changing,
    in the second question, mammal with animal,
    reaction times get slower.

C. Q. task (inclusion in classes, true-false)
Is the chair a piece of furniture?Is the tree a
part of a car? Is the cat is a mammal? Is the
square a geometric figure?
26
Semantic memory concepts and schemas
  • In the alternative model by Smith (1974) the
    semantic storage is based on feature matching
    rather than semantic hierarchies.
  • However, as both models could not explain all
    data, the new approach of sematic networks was
    proposed.
  • Connectionist models (Parallel Distributed
    Processing), explain the semantic memory in terms
    of semantic networks.
  • According to this approach, working memory would
    be the part of the network working in a given
    moment. A node that activates another is called
    prime, its effect priming.

mammal
feline
primate
chimpanzee
macaque
27
Cognitive neurosciences of memory
  • The first attempts to localize memory in the
    brain were quite unsuccessful.
  • Indeed, the attempts to localize specific
    memories, called engrams by Lashley brought to
    the conclusion that memories do not have a
    specific location.
  • However, there seems to be a correlation between
    brain structures and general memory functions.
  • In particular, the finding of double
    dissociations has given fundamental insights. For
    example, lesion to the left parietal cortex
    compromise STM leaving LTM unaffected, while
    medial temporal lesions compromise LTM while
    leaving STM unaffected.
  • Double dissociations were found also between
    declarative and non-declarative memory.

28
Cognitive neurosciences of memory
  • It seems now that different structures have
    different roles for memory.
  • The cortex seems to be involved in the LT storage
    of sensory information.
  • The hyppocampus has a key role for the
    declarative knowledge, complex learning and the
    LTM consolidation (perhaps by linking material
    stored in spared areas of the brain).
  • The basal ganglia are involved in the implicit
    memory, but not in the priming.
  • The cerebellum has to do with the classically
    conditioned responses.
  • At the level of single neurons, a repetitive
    stimulation of a neural path increases the
    likelyhood of firing of the post-synaptic
    neurons, effectively decreasing their threshold.
  • About the neurotrasmitters, serotonine,
    acetylcoline and noradrenaline increase the
    memory-related neural transmission.
  • In the normal hyppocampus there is a high
    concentration of acetylcoline, which is
    substantially reduced in Alzheimer patients.
  • In alcoholics, the serotonin level is seriously
    altered and is correlated with diencephalic
    damages. A typical deficit in these patients is
    the Korsakoff syndrome, that involves a severe
    form of amnesia anterograde.

29
Memory processes
  • We are now going to focus onto memory processes
    encoding, storage and retrieval.
  • These three processes are assumed to be
    sequential in order to start every next stage a
    minimum output from the previous stage needs to
    be provided.
  • Encoding has to do with the language the system
    uses to understand the outer world (e.g., binary,
    analogic, etc.).
  • Storage has to do with the properties of the
    memory stores.
  • Retrieval has to do with the mechanism by which
    specific stored information is selected and used
    for contingent behavior.

30
Read in silence this piece
The procedure is actually quite simple. First you
arrange items into different groups. Of course
one pile may be sufficient depending on how much
there is to do. If you have to go somewhere else
due to lack of facilities that is the next step
otherwise, you are pretty well set. It is
important not to overdo things. That is, it is
better to do too few things at once than too
many. In the short run this may not seem
important but complications can easily arise. A
mistake can be expensive as well. At first, the
whole procedure will seem complicated. Soon,
however, it will become just another facet of
life. It is difficult to foresee any end to the
necessity for this task in the immediate future,
but then, one can never tell. After the procedure
is completed one arranges the materials into
different groups again. Then they can be put into
their appropriate places. Eventually they will be
used once more and the whole cycle will then have
to be repeated. However, that is part of life.
31
this was the original piece presented by
Bransford and Johnson (1972) to the subjects of
their experiment can you recall the key
parts What is it about??? would you agree it
was about washing clothes??? !!!!!
32
Information encoding
  • Conrad (1964) did an experiment aimed to
    understand the code for brief, temporary storing
    (like retaining a telephone number before to
    store it in our cell phone).
  • A sequence of 6 letters were presented very
    briefly and subjects were asked to report them as
    they saw them immediately after the stimuli.
    Regardless of whether the letters were presented
    visually or acustically, the errors were always
    of phonetic nature (letters with similar sounds
    were confused). Conrad concluded that STM had an
    acustic code.
  • Baddeley (1966) found similar acoustic code for
    the semantic memory. He noticed that the recall
    of acustically similar words (i.e. rhymes) is
    much worse than that of acustically uncorrelated
    words, while there is no such difference for
    words semantically related/unrelated.
  • However, the use of semantic and visual codes was
    found in later studies by Shulman (1970) and
    Posner (1969).

33
Information encoding
  • Whereas STM uses mainly sensory codes, there are
    many converging data that the preferential code
    for LTM is semantic.
  • A fundamental study was made by Grossman and
    Eagle (1970).
  • Analyzing the false alarms with the 18
    distractors of the control list, the errors with
    sematically related distractors were twice as
    frequent than with unrelated distractors.

Learning list
Test list with distractors
1) house2) clock3) spaghetti4) cup 41)
gondola
1) clock2) train3) cup4) italy 41) boat
Unrelated distractor
5 waiting
Semantically related distractors
34
How soon do we forget?
  • A classical experiment by Petersen e Petersen
    (1959) has shown the time by which information
    not reiterated is forgotten.

ISTRUCTIONS
  • A string of 3 consonants will be displayed for 1
    second, followed by a number. As soon as you will
    se the number you will have to count backwards
    (with no recall pauses!!!) subtracting 3 numbers
    as fast as you can (e.g. if 17 is displayed, you
    will count 14, 11, 8, 5) while keeping your eye
    on the display. At a certain point a red spot
    will signal to stop. At the stop signal write
    down the string as you recall it. We will do it
    for 7 trials.

gtk
rtm
zxt
klf
qkl
tvm
zps
74
53
72
47
59
101
96
35
How soon do we forget?
  • Class data plotted

36
How soon do we forget?
  • This experiment is perfect to show how well
    laboratory investigations can investigate the
    properties of memory.
  • Once the stimulus set is defined, the lag
    between learning and recall is systematically
    varied and performance is measured.
  • In the original P. P. experiment there was a
    drop of accuracy up to about 10 for lags of 18
    seconds.
  • The data were interpreted in terms of
    interference new learnings interfere with old
    information by obscuring it.
  • An alternative account is that information
    undergoes to a natural decay independently of
    interference.
  • The data of the P. P. experiments were taken
    to suggest that counting backwards might have
    interfered with the recall.

37
The oblivion interference or decay?
  • Interference and trace decay qre the two main
    explanations of the reasons of forgetting.
  • The study of Brown e Peterson was taken to
    support the interference model.
  • There are two types of interference proactive
    and retroactive.
  • The first is an effect of what happens after the
    material is presented, as in the B P
    experiment, the second occurs before the target
    information is presented.

38
Read these words, presented for 1 each on the
left side of the screen , then write down
all you can recall
telephone cloud book tree shirt cat bulb chalk cha
ir flower clock bat carpet soup pillow
39
Serial Position effect
40
The oblivion interference or decay?
  • The serial presentation curve can be explained by
    the interference model the first elements of the
    list endure only the proactive interference, the
    last ones only the retroactive interference, the
    intermediate both types.
  • According to the decay account, the trace would
    fade out naturally, without interferences, unless
    it is not consolidated.
  • Testing the decay hypothesis is not as easy as
    testing the interference hypothesis, in that its
    not easy to exclude interferences and reharsal.

41
Trasfer to LTM and consolidation
  • How do we face oblivion and transfer data in the
    LTM register?
  • Consolidation, within this context, is the
    process of integration, by association, of new
    information with previously existing information.
    This process would be the base of the transfer of
    information.
  • Another basic mechanism is the attentive
    selection of information attention would
    increase the chance of consolidation.
  • During the process of consolidation, information
    would be deformed and degraded. By metamemory are
    meant the strategies used to help and improve our
    memories and their consolidation.
  • The most widely used strategy is reharsal, that
    can be overt or covert.
  • This practice effect depends mainly on the total
    time employed, even though studies show that
    distributed sessions are more effective than only
    one long session. Moreover, distributed practice
    is more effective when the sessions take places
    in different contexts.

42
Organizing information
  • The stored information is organized in different
    ways.
  • Specific strategies tho organize memories are
    called mnemonics.
  • There are different mnemonics. The most common
    ones block notes and diaries.
  • The use of mnemonics is of particular importance
    for the perspective memory. In this case we use
    external,physical cues, or constraints that act
    as reminders by hindering the continuation of the
    activity unless one actively notice them.

43
Retrieval
  • Saul Sternberg (1966) did a series of experiments
    of memory scanning to study the retrieval from
    STM.
  • Subjects were presented with lists of numbers of
    varying length and, after a short pause, they
    were asked whether a test number was present in
    the list or not.
  • They measured RTs of individual subjects

44
Retrieval
  • If the mechanisms of recovery were parallel,
    then RTs should not depend on the length of
    the list (RTslist1RTslist2).
  • Viceversa if the mechanisms were serial
    (RTslist1gtRTslist2).
  • Assuming a serial process, if the matching of the
    test with the items of the list was exaustive
    (including all the items), RTs should not depend
    on the serial position of the item in the list.
  • Viceversa if the problem was self-terminating.

AGTKDORSYW
SLKRDZ
AGTKDORSYW
SLKRDZQZAL
AGTKDORSYW
SLKRDZQZAL
45
NYU Florence spring 2007 results
46
Retrieval
  • The results point clearly to a serial exaustive
    mechanism

serial
exaustive
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