memory psycology

• 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 is the lack of standardisation and appreciation of scientific methods
• Bahrick et al's 1975 study has high ecological validity due to the use of meaningful stimuli and a methodology with high mundane realism
• The Petersen et al and Miller et al studies have low mundane realism, producing findings with little ecological validity
• More recent research suggests Miller may have over-exaggerated the capacity of STM, which is more similar to 4 chunks
• 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


  • 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


  Repeating new information to keep it in STM
• Long-term memory (LTM)


  • Semantically encoded, unlimited capacity, very long duration (over 46 years)

  
• Retrieval


  When information is transferred back into the STM
• The MSM does not represent different types of LTM (procedural, semantic, episodic)
• The MSM suggests that the amount of maintenance rehearsal determines the likelihood of information passing into LTM, whereas Craik and Watkins suggest the type of rehearsal is more important
• Multi-Store Memory Model


  • Acknowledges qualitative differences between STM and LTM, but incorrectly represents STM as a single, unitary store

  
• Episodic memory


  Memories with personal meaning, details of when and how events occurred, and associated people and places
• Semantic memory


  Memories of the world and associated knowledge

  
• Procedural memory


  Memories of learned skills

  
• 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

  
• Differentiating between types of LTM has practical applications, such as improved treatments for mild cognitive impairments
• Cohen and Squire's distinction between declarative (conscious recall) and non-declarative (unconscious recall) memories is different from Tulving's classification

  
• Cases of HM and Clive Wearing support the idea of different types of LTM with separate neurological bases
• Working Memory Model (WMM)


  Suggests STM is made up of the central executive, phonological loop, visuo-spatial sketchpad, and episodic buffer

  
• Central executive


  • An 'attentional process' with limited processing capacity, allocates tasks to the slave systems
• Phonological loop


  • Processes auditory information and allows for maintenance rehearsal
• Visuo-spatial sketchpad


  • Combines visual and spatial information, capacity around 4-5 chunks
• Episodic buffer


  • Integrates all types of data processed by the other stores, links STM to LTM
• The central executive has not been precisely defined in the WMM
• Shallice and Warrington's study of KF supports the WMM by showing separate components for auditory and visual STM
• Dual-task performance studies support the limited processing capacity of the central executive
• Neuroscanning evidence supports the role of the central executive in allocating tasks and having limited capacity
• Interference


  When the recall of one memory blocks the recall of another, causing forgetting or distorted perceptions