SHORT TERM MEMORY

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SHORT TERM MEMORY

• AIMS OBJECTIVES
• The aim of this lecture is to review current
  approaches to short term memory.
• At the end of the lecture you will have learned
• What is short term memory
• The modal multi-store model
• The working memory model
• Why people become amnesic.

• CORE READING
• Parkin, A. (2000). Essential Cognitive
  Psychology. Psychology Press, Chapter 4.
• SUPPLEMENTARY READING
• Cowan, N. (2000). On human memory Evolution,
  progress, and reflections on the 30th anniversary
  of the Atkinson-Shiffrin model. American Journal
  of Psychology, 113(4), 639-664.

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William James (1890s)

• Primary memory.
• Whats in consciousness at the present time.
• We now call this short term memory (STM).
• Help us to remember a new telephone number

• Secondary memory.
• What is permanently etched upon our minds.
• We now call this long term memory (LTM).
• Help us remember who the number belongs to

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Modal (multi-store) model

• Atkinson and Shiffrin (1968).
• Information flows from sensory register to short
  term memory STM and then on to a permanent long
  term memory or LTM.

• Transfer of information controlled by top down
  processes such as attention and rehearsal.
• Rehearsal is used to transfer information from
  STM to LTM.
• Capacity is limited

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iconic
echoic
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Capacity of iconic memory
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Serial position effects

• Probe digit task (Waugh Norman, 1965).
• 17425938?.765?

• Which digit followed the probe 9?
• Performance declines as number of intervening
  items is increased.
• Items are displaced from STM over time.

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Digit span task 2,6,4,1,8,0,2 Items moved out of
memory when capacity 7-2
1742593 number of intervening items 765?
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Memory fades quickly
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Memory fades quickly
Capacity of STM7-2 items these can be digits,
words, or chunks 1066, 911, 2002
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Rey Auditory Verbal Learning Test

• 1. drum
• 2. curtain
• 3. bell
• 4. coffee
• 5. school
• 6. parent
• 7. moon
• 8. garden
• 9. hat
• 10. farmer
• 11. nose
• 12. turkey
• 13. colour
• 14. house
• 15. river

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Serial position curve

• Primacy effect.
• Memory for items presented first in a list of
  words recalled better than words presented in the
  middle of a list.

• Recency effect.
• Memory for items presented last in a list are
  recalled better than words presented in the
  middle of a list.
• Shows a dissociation of memory function.

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Short term memory
Long term memory
Dissociable (modular) cognitive processes can be
influenced by different variables
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Rey Auditory Verbal Learning Test

• 1. drum
• 2. curtain
• 3. bell
• 4. coffee
• 5. school
• 6. parent
• 7. moon
• 8. garden
• 9. hat
• 10. farmer
• 11. nose
• 12. turkey
• 13. colour
• 14. house
• 15. river

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Two memory processes

• The primacy effect is altered by
• the word frequency of items used in the task
• Intelligence quotient of the participants (IQ)
  (higher IQ recall more first words from list).
• Speed of presentation.

• The recency effect is altered by
• the use of a distracter task between listening
  and recalling (could be a simple addition task)
• a time delay between learning and recall (could
  be as little as 10 seconds).

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Frequency has an influence on primacy effect but
does not affect recency effect
Intelligence also interacts with serial recall
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Recency effect is largest with no delay to recall
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Amnesia

• Brain damage in the medial temporal lobes can
  result in selective memory disorders.
• Short-term memory (e.g., digit span) can be
  normal in amnesia e.g. HM by Corkin (1994).

• Other patients have STM impaired with (largely)
  preserved long term memory e.g., patient KF
  reported by Shallice and Warrington (1970).
• The double dissociation suggests that STM and LTM
  are separable systems.

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Amnesia

• Two different types of memory loss can occur
  following damage to the brain.

• Retrograde amnesia
• memory for previously learned information can no
  longer be recalled.
• Retrieval problems
• Korsakoffs syndrome.
• Anterograde amnesia
• learning of new information is impaired.
• Registration problems
• Head injured patients

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Emotional memories
hippocampus
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Registration impairment

• HM
• 1953 Bilateral temporal lobectomy for severe
  epilepsy including portions of the hippocampus
  and amygdala.
• Can remember very little information since the
  operation

• "His experience seems to be that of a person who
  is just becoming aware of his surroundings
  without fully comprehending the situation,
  because he does not remember what went before
  Milner (1978).
• like waking from a dream (HM).
• Jigsaw puzzles

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Patient KF

• Warrington and Shallice (1970) reported KF.
• She could learn visual paired associates of words
  (apple-orange).
• She could not perform a simple digit span task
  (only 2 correct).

• If STM (digit span) is impaired then how can new
  learning take place?
• Meaning of words (LTM) is used to learn new
  pairs.
• KF used a meaning based code but could not use a
  sound based code to learn new information.

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What processes do we use to actively learn new
information?
visual
verbal
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The working memory model

• Baddeley and Hitch (1974) proposed a model of
  memory which has superseded the unitary STM store
  assumption.

• The model has three separate components
• a modality free central executive
• an articulatory or phonological loop
• a visuo-spatial sketchpad.

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Minds eye
Inner voice
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Articulatory suppression engages this part of the
loop
Phonological loop is used to rehearse temporal
order has a capacity of around 7-2 items
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Role of the phonological loop

• Vocabulary acquisition
• Memory span (repetition of nonwords such as fep)
  has a strong relationship to vocabulary
  development.
• larger span is positively correlated with
  vocabulary size r.78, p

• Reading skill
• People with dyslexia (or reading problems) show
  less evidence of phonological confusion in memory
  (CDEPT).
• cannot use phonology?

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BA 40, 44
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Visuo-spatial sketchpad

• This component of the WM model processes
  information that is visual or spatial in nature.
• Visualising what is around the next corner.
• Using maps.

• Inner eye (Leonardo).
• Is used for geographical orientation and for the
  planning of spatial tasks.
• People with dyslexia can often show extremely
  good performance on visuo-spatial tasks.

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Central executive

• The central executive allocates attention to
  inputs and directs the operation of other (slave)
  components in memory.
• It is amodal that is it can process information
  from any sensory modality.

• This component has a limited capacity.
• It is used for cognitively demanding tasks.
• Frontal lobe?

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Trails A
Trails B
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Homonculus
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Frontal
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Summary

• Primary and secondary memory have been seen as
  separate systems 100 years.
• Experimental studies show a dissociation in
  function - i.e. primacy and recency effects.
• The modal model can explain primacy and recency
  effects on memory but may have limited
  explanatory power.