Memory

• Coding


  The format or 'type' of information which is stored in each memory store
• Coding in memory


  • Acoustic in short-term memory
  • Semantic in long-term memory
• Capacity


  The volume of information/data which can be kept in any memory store at any one time

  
• Capacity of STM


  • Thought to be 7 +/- 2 items (Miller)
• Capacity of LTM


  • Unlimited
• Duration


  The amount of time that information can be stored in each memory store
• Duration of STM


  • 18-30 seconds (Petersen et al)
• Duration of LTM


  • Unlimited (Bahrick et al)
• A key issue with historical psychological research, particularly concerning Jacobs, is the lack of standardisation and appreciation of scientific methods
• The current laboratory experiment methodology produces highly reliable and valid data through controlling and so removing the effects of extraneous and confounding variables
• The same is unlikely to be said of Jacobs, where confounding variables such as a noisy room or difficult word lists, may have had a greater influence on accuracy of recall, leading to unreliable results
• A particular strength of Bahrick et al's 1975 study is the use of meaningful stimuli, and a methodology which is high in mundane realism
• The findings of Bahrick et al have high ecological validity because they can be easily generalised to real-life, due to the stimuli reflecting those which we would often try to learn and recall in our day to day lives: information with personal and meaningful value
• The key issues with the Petersen et al and Miller et al studies is that they feature methodologies with low mundane realism, thus producing findings with little ecological validity
• This is due to the use of artificial stimuli which has little personal meaning to the participants, and so does not accurately reflect everyday learning experiences
• This therefore limits the generalisability of such findings
• More recent research has suggested that Miller may have over-exaggerated the capacity of STM, and that the capacity is more similar to 4 chunks as opposed to the original 5-9 limit
• This may reflect the outdated methodologies adopted by Miller and specifically, the lack of control over confounding variables which may have contributed to this inaccurate estimate
• Multi-store memory model (MSM)

  Represents how memory is stored, transferred between the different stores, retrieved and forgotten

  
• Stores in the MSM

  • Sensory register
  • Short-term memory
  • Long-term memory

  
• Sensory register


  • Contains one sub-store for each of the 5 senses
  • Has a huge capacity
  • Has a duration of less than half a second
• Information will only pass from the sensory register to the short-term memory store if we pay attention to it

  
• Short-term memory (STM)


  • Acoustically encoded (Baddeley)
  • Capacity of 7+/- 2 items (Miller)
  • Duration of 18-30 seconds (Petersen)
• Maintenance rehearsal


  Repeating the new information to ourselves, allowing the information to be kept in the STM
• Prolonged maintenance rehearsal


  Allows the information to pass into the LTM
• Lack of maintenance rehearsal

  Causes forgetting
• Long-term memory (LTM)


  • Semantically encoded
  • Has an unlimited capacity
  • Has a very long duration (over 46 years, as shown by Bahrick et al)
• Retrieval


  When information is transferred back into the STM, and will continue to pass through the maintenance loop afterwards
• The MSM does not represent the different types of LTM (procedural, semantic and episodic) as proposed by Tulving et al
• The MSM does not represent that some types of LTM can be retrieved unconsciously (e.g. procedural) whilst others must be retrieved consciously (e.g. semantic)
• The MSM suggests that the amount of maintenance rehearsal determines the likelihood that the information will pass into the LTM, whereas Craik and Watkins (1973) suggest that it is the type of rehearsal which is more important
• Craik and Watkins suggest that elaborative rehearsal, instead of prolonged rehearsal, is needed to transfer information from the STM into the LTM, by making links with existing knowledge
• The MSM acknowledges the qualitative differences between STM and LTM by representing them as separate stores
• The MSM incorrectly represents STM as a single, unitary store
• Shallice and Warrington found that their amnesiac patient KF had poor STM recall for auditory stimuli, but increasingly accurate recall for visual stimuli, suggesting that there may be multiple types of STM
• Episodic memory


  Memories which have some kind of personal meaning to us, alongside details as to when and how these events occurred, as well as the associated people and places
• Semantic memory


  Our memories of the world and the associated knowledge
• Procedural memory


  Our memories of 'learned skills', such as swimming or driving
• Episodic and semantic memories must be recalled consciously, whereas procedural memories are recalled unconsciously
• Petersen et al. demonstrated that semantic memories were recalled from the left prefrontal cortex, whilst episodic memories were recalled from the right prefrontal cortex