Cognitive Psychology

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Cognitive Psychology

• The working Model of Memory
• By Baddeley and Hitch (1974)

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Learning objectives

• Understand what is meant by the concept of
  working memory.
• Describe the working memory model and understand
  the functions and limitations of its components.
• Describe and evaluate the evidence on which the
  working model is based.
• Understand the strengths and weaknesses of the
  model.

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Background to the WMM

• Baddeley and Hitch (1974) believed that there was
  more to STM than in the multi-store model (i.e.
  more than just being one store house).

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The components of the WMM

• A complex and flexible system with different
  components

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A MORE ACTIVE MODEL OF MEMORY
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3 main components

• The central executive (supervisor)
• Has overall control
• Limited capacity
• Can process information from any sensory modality

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Central Executive

• Responsible for a range of control processes
  e.g.
• setting task goals,
• monitoring and correcting errors,
• starting rehearsal process,
• switching attention between tasks,
• inhibiting irrelevant information
• Retrieving information from LTM
• Coordinating activity needed to carry out more
  than one process at a time.

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Two slave systems

• The slaves to the CE can be used as storage
  systems
• Which frees up some of the CEs capacity to deal
  with more demanding information processing tasks.
  
• The slave systems have separate responsibilities
  and work independently of one another.

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1. Phonological Loop

• (the inner voice) has limited capacity
• A temporary storage system for verbal information
  in a speech-based form.

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2. The visuo-spatial sketchpad

• The inner eye
• Limited capacity
• Temporary memory system for holding visual and
  /or spatial information

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Revised model (1999)

• Phonological loop now passive storage system
  called
• Phonological store which is linked to a rehearsal
  system called
• The Articulatory Loop
• Maintained by subvocal repetition.
• The visuo-spatial sketchpad passive visual
  store called
• Visual cache (collection of data) which is linked
  to an active inner scribe that acts as a
  rehearsal mechanism.

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The dual task method

• To test the function of STM, Baddeley and Hitch
  asked participants to perform
• A reasoning task (sentence-checking)
• While reciting a list of 6 digits.
• According to the multi-store model the capacity
  of the STM would be taken up with the digit task.

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Recite the six digit number 482917 aloud while
ticking True or False

• 1. B is followed by A BA
• 2. A is preceded by B AB
• 3. A is not followed by B BA
• 4. B follows A AB
• 5. B does not follow A BA
• 6. B is not followed by A AB
• 7. A follows B AB
• 8. B is not preceded by A AB
• 9. A is not followed by B BA
• 10. B does not precede A AB

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Findings

• Participants made very few errors on either task
  (although the speed of sentence checking was
  slightly slower than when done on its own).

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Conclusions

• Baddeley and Hitch concluded that STM must have
  more than one component and
• Must be involved in processes other than simple
  storage, e.g. reasoning, understanding and
  learning.
• STM is a kind of workspace where a variety of
  operations can be carried out on both old and new
  memories.

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A MORE ACTIVE MODEL OF MEMORY
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Very important

• Two tasks can be carried out at the same time as
  long as
• They are being carried out by different
  modalities (parts of the memory system).
• LTM is a more passive store for previously
  learned material.
• The ACTION is in the STM.

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Evidence for the phonological loop

• Baddeley et al. (1975)
• Visual presentations of word lists for a brief
  time
• Participants asked to write them down in serial
  order.
• Condition 1 lists consisted of 5 words
  familiar, one-syllable English words, e.g. harm,
  wit, twice.
• Condition 2 5 words, polysyllabic, e.g.
  organisation, university, association.

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findings

• More short words were recalled
• This was called the word length effect
• Conclusion
• Capacity of the loop is determined by the length
  of time it takes to say a word rather than by
  the number of items.
• The estimated time was 1.5 seconds

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Method

• Laboratory experiment using a repeated measures
  design
• Evaluation
• Well controlled
• Longer words may be less familiar than short
  words. This could have affected the recall rather
  than the length.
• No ethical issues if fully informed consent
  obtained.

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The word length effect under articulatory
suppression

• Participants were given a task that would usually
  make use of the articulatory loop
• Asked to repeat a meaningless chant aloud e.g.
  la-la-la
• The word length effect disappeared and recall for
  short words was no better.
• This suggests that a verbal rehearsal system is
  important and when suppressed, processing has to
  take place elsewhere (maybe the central executive)

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Evidence for the visuo-spatial sketchpad

• The visual store also has limited capacity.
• Shepard and Feng (1972) asked participants to
  imagine folding flat shapes in order to make a
  cube.
• They had to decide whether the arrows would meet
  head on.

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findings

• The time taken to make the decision was related
  to the number of folds they would have had to
  make if they had actually been doing the task.
• Visual images work in a similar way to real life
  perception.
• People are likely to find it difficult to do two
  tasks simultaneously if they both use the
  visuo-spatial sketchpad.

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Research Baddeley et al. 1973

• Participants were given a tracking task
  (following a spot of light with a pointer around
  a circular path while imagining block capitals
  such as H, T, F and E.

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• Participants were asked to start at the bottom
  left-hand corner, to respond to each angle with a
  yes if it included the bottom or top line of
  the letter and a no if it did not.

F H
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findings

• Participants had enormous difficulty in tracking
  the spot of light and accurately classifying the
  corners.
• The two tasks were competing for the same limited
  resources of the visuo-spatial sketchpad.
• This is supported by the fact that participants
  could carry out the tracking task while
  performing a verbal task.

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Logie (1995)

• Suggested that the visual cache stores
  information about visual form and colour
• The inner scribe processes spatial and movement
  information.

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Klauer and Zhao (2004) supported this

• Participants carried out one of two tasksA
  visual taskA spatial task
• At the same time they were asked to do either
• A spatial interference task
• A visual interference task
• No secondary task (control condition)

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findings

• Performance of the spatial task was much poorer
  for those carrying out a spatial distractor task
  at the same time compared with those doing the
  visual distractor task and vice versa.
• PET scans show evidence for separate systems.
  Brain activity differs.
• More activity in the left half for visual
• More activity in the right half for spatial

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Evidence for central executive

• Critical role in attention, planning and
  coordination.
• Most flexible component of the working memory.
• More difficult to find evidence for.
• Easier to study the slave systems.
• Research on the CE tends to focus on the
  different functions.

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Baddeley (1996)

• Investigated the functions of the CE in selective
  attention and switching retrieval plans.
• Participants were asked to generate random
  strings of digits by pressing numbered keys on a
  keyboard.

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Try this (if you have a computer)

• Think of a sequence of eight digits that show no
  systematic pattern (Note that patterns easily
  emerge so this is difficult).
• At the same time
• Recite the alphabet
• Count from 1
• Alternate between letters and numbers
  (A1B2C3D4E5F6 etc)

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findings

• Baddeley found that the generated digit string
  became considerably less random in Condition 3
  when particpants were switching from alphabet to
  numbers at the same time.
• Baddeley concluded that both the random number
  generation task and the alternation task were
  competing for the same central executive
  resources.

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Evaluation of the working memory model

• A very influential model
• Accepted by cognitive psychologists in preference
  to the idea of a STM store.
• More plausible than the multi-store model because
  it explains the STM in terms of active process
  rather than passive storage alone.
• Verbal rehearsal is accepted as one optional
  process within the articulatory loop rather than
  the only way to transfer information to the LTM.

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More positives of the WMM

• It can account for some of the findings that the
  MSM finds difficult to explain.
• Research support comes from dual-task studies
  although
• KF could remember visual but not verbal stimuli
  in STM supports the idea of at least 2 separate
  systems in the STM.

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• Brain scans show different areas of the brain are
  used for visual and verbal tasks which supports
  the WMM.
• The role of the CE is not fully understood and it
  is likely to be comprised of more than one
  component.
• Fails to account for musical memory as we are
  able to listen to instrumental music without
  impairing performance on other acoustic tasks.