Memory

• Multistore model of memory


  Atkinson and Shiffrin 1968, a theoretical cognitive model of how the memory system processes information
• Sensory register


  1. Receives raw sense impressions

  2. Attention passes info to short-term memory

  3. Coding is modality specific

  4. Capacity is very large

  5. Duration is very short (250 milliseconds)
• Short-term memory


  1. Receives info from sensory register by paying attention or from long-term memory by retrieval

  2. Keeps information by repeating maintenance rehearsal or passing to long-term memory

  3. Coding is acoustic

  4. Duration is approximately 18 seconds

  5. Capacity is 7 plus or minus 2 items
• Long-term memory


  1. Very long duration, permanent memory storage

  2. Theoretically unlimited capacity

  3. Coded semantically in the form of meaning

  4. Information must be passed back to short-term memory to be used
• Words at the start and end of word lists were more easily recalled (Primacy and recency effect)
• Recall of a random row of a 12x12 grid flashed for 120th of a second was 75%, suggesting all the rows were stored in sensory register
• Immediate recall was worse for acoustically similar words and recall after 20 minutes was worse for semantically similar words, suggesting short-term memory is coded acoustically and long-term memory is coded semantically
• Capacity of short-term memory

  Average 7 items for letters, 9 for numbers (Jacobs)
• Duration of short-term memory

  Less than 10% recall of a 3-letter trigram after 18 seconds with an interference task (Peterson and Peterson)
• Capacity of long-term memory

  75% recall of critical details after 1 year, 45% after 5 years (Wagner's diary study)
• Duration of long-term memory

  90% recall of school friends' names after 15 years, 80% after 48 years (Bahrick)
• Cognitive tests of memory like the MSM are often highly artificial, low in mundane realism, and conducted in lab environments, so findings may not generalize to real-world memory use
• Types of long-term memory

  • Declarative (explicit, conscious)
  • Non-declarative (implicit, unconscious)
  • Episodic (experiences and events)
  • Semantic (facts and knowledge)
  • Procedural (skills and habits)
• Patients with hippocampal damage had episodic amnesia but intact semantic memory, suggesting they use different brain regions (Vargha-Khadem)
• Clive Wearing had retrograde amnesia for episodic and semantic memories, but could gain new procedural memories, suggesting they use different brain areas
• Generalizing findings from idiographic case studies to explain memory in the wider population is problematic, as other unknown issues could be unique to that individual
• Working memory model


  Baddeley and Hitch 1974, a theoretical counter model of information processing that replaced the STM store in the MSM
• Working memory model components

  1. Central executive (controls attention and filters information)

  2. Phonological loop (processes sound information)

  3. Visuospatial sketchpad (processes visual and spatial information)

  4. Episodic buffer (general store to hold and combine information)
• Performing two visual tasks or a visual and verbal task simultaneously is better when they use different processing, suggesting the phonological loop and visuospatial sketchpad are separate systems (Baddeley)
• Brain injury patient KF had selective impairment to verbal short-term memory but not visual functioning, suggesting the phonological loop and visuospatial sketchpad are separate processes in the brain (Shallice and Warrington)
• The working memory model seems more accurate than the short-term memory component of the MSM in describing how memory is used as an active processor
• Memory tasks used in research often lack mundane realism and may not generalize to real-world memory use
• The central executive concept in the working memory model needs further development, and the inclusion of the episodic buffer is part of this (Baddeley)
• It is impossible to directly observe the processes described in memory models, so inferences and assumptions must be made that could be incorrect
• Interference theory


  We forget because our long-term memories become confused or disrupted by other information
• Types of interference


  • Proactive interference (old information disrupts new)
  • Retroactive interference (new information disrupts old)
  • Similarity interference (more likely when information is similar)
  • Time sensitivity interference (less likely with longer gaps)
• Retrieval failure due to absence of cues

  Information is in long-term memory but forgetting happens due to lack of appropriate prompts or context
• The encoding specificity principle states that context-dependent and state-dependent cues in the environment and internal state can aid memory retrieval
• Retroactive interference


  New information disrupts old information
• Proactive interference


  Previously learned information causes confusion in the coding of later information
• Interference only explains forgetting when two sets of information are similar and one learned closer together in time
• Context dependent cues


  Aspects of our external environment that work as cues to memory
• State dependent cues


  Aspects of our internal environment that work as cues to memory
• Category or organizational dependent cues


  Providing cues that relate to the organization or category of memories
• The most effective cues have fewer things associated with them, the lack of organization cues inhibits memory
• Retroactive interference


  • Adding new street names to memory makes recalling old street names harder
• Proactive interference


  • Previously learned word combinations cause confusion in the coding of later word lists
• Interference may only explain a temporary loss of information, not a permanent loss
• Research into forgetting has practical applications for students developing effective revision strategies
• Reconstructive memory


  Memory is not an accurate recording of events, it's reconstructed in recalling