Memory

• Coding in memory stores:

  • Acoustic coding in short-term memory
  • Semantic coding in long-term memory
• Capacity of memory stores:

  • Short-term memory capacity is 7 +/- 2 items
  • Long-term memory capacity is unlimited
• Duration of memory stores:

  • Short-term memory duration is 18-30 seconds
  • Long-term memory duration is unlimited
• Multi-Store Model of Memory:

  • 3 stores: sensory register, short-term memory, long-term memory
  • Sensory register has a huge capacity but duration of less than half a second
  • Short-term memory is acoustically encoded, has a capacity of 7+/- 2 items, and a duration of 18-30 seconds
  • Long-term memory is semantically encoded, has unlimited capacity, and very long duration
• Types of Long-Term Memory:

  • Episodic, semantic, procedural memories
  • Episodic and semantic memories recalled consciously, procedural memories recalled unconsciously
• Working Memory Model:

  • STM consists of central executive, phonological loop, visuo-spatial sketchpad, and episodic buffer
  • Central executive allocates tasks to slave systems
  • Phonological loop processes auditory information
  • Visuo-spatial sketchpad combines visual and spatial information
  • Episodic buffer integrates all data processed by other stores
• Historical psychological research, particularly concerning Jacobs: 'The lack of standardisation and appreciation of scientific methods'
• The current laboratory experiment methodology produces highly reliable and valid data through controlling and removing the effects of extraneous and confounding variables
• A particular strength of Bahrick et al’s 1975 study is the use of meaningful stimuli and a methodology high in mundane realism
• The findings of Bahrick et al’s study have high ecological validity because they can be easily generalised to real-life due to reflecting 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, producing findings with little ecological validity
• The use of artificial stimuli in the Petersen et al and Miller et al studies limits the generalisability of the findings as they do not accurately reflect everyday learning experiences
• 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• This may reflect the outdated methodologies adopted by Miller and specifically, the lack of control over confounding variables which may have contributed to this inaccurate estimate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 multi-store memory model

  • Sensory register
  • Short-term memory
  • Long-term memory
• The sensory register contains one sub-store for each of the 5 senses, e.g., an echoic store for auditory information
• The sensory register has a huge capacity but a duration of less than half a second
• Short-term memory (STM)

  • Acoustically encoded
  • Capacity of 7+/- 2 items
  • Duration of 18-30 seconds
• Maintenance rehearsal occurs when we repeat the new information to ourselves, allowing the information to be kept in the STM
• STM

  1. Acoustically encoded (Baddeley)

  2. Capacity of 7+/- 2 items (Miller)

  3. Duration of 18-30 seconds (Petersen)
• Maintenance rehearsal

  Repeating new information to ourselves to keep it in STM
• Prolonged maintenance rehearsal


  Allows information to pass into LTM
• Lack of maintenance rehearsal

  Causes forgetting
• LTM

  1. Semantically encoded

  2. Unlimited capacity

  3. Very long duration (over 46 years, Bahrick et al)
• Retrieval


  Transfer of information back into STM, then through maintenance loop
• Types of LTM

  • Procedural
  • Semantic
  • Episodic
• MSM


  Does not represent different types of LTM, sees LTM as a single store
• Some types of LTM

  Can be retrieved unconsciously (e.g. procedural) or consciously (e.g. semantic)
• Amount of maintenance rehearsal


  Determines likelihood of information passing into LTM (MSM) vs. type of rehearsal (Craik and Watkins)
• Elaborative rehearsal


  Needed to transfer information from STM to LTM by making links with existing knowledge (Craik and Watkins)
• STM and LTM differences

  STM encoded acoustically, LTM encoded semantically with longer duration (MSM)
• STM in MSM

  Incorrectly represented as a single store, may have multiple types (Shallice and Warrington)
• Types of Long-Term Memory

  • Episodic
  • Semantic
  • Procedural
• Episodic memory


  Personal memories with details of events, people, and places
• Semantic memory


  Memories of the world and associated knowledge
• Procedural memory

  Memories of learned skills
• Episodic and semantic memories


  Recalled consciously, procedural memories recalled unconsciously
• Semantic memories


  Recalled from left prefrontal cortex, episodic memories from right prefrontal cortex (Petersen et al)
• Different types of LTM

  Have different neurological bases, recalled from different parts of the brain (Petersen et al)