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 but varies per store)
• Short-term memory


  1. Receives info from the 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 seven plus or minus 2 items
• Long-term memory


  1. Very long duration, permanent memory storage

  2. Theoretically unlimited capacity

  3. Forgotten information appears to just be inaccessible

  4. Coded semantically in the form of meaning

  5. Must be passed back to short-term memory to use the information
• 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 1/120th of a second was 75%, suggesting all the rows were stored in sensory register but forgotten too quickly
• 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 plus or minus 2 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

  Very large, potentially limitless (Wagner)
• Duration of long-term memory

  Very long, potentially limitless (Bahrick)
• Cognitive tests of memory like the multistore model are often highly artificial, low in mundane realism, and conducted in lab environments, so the 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)
• Patients with hippocampal damage have episodic amnesia but can still learn semantic information, suggesting semantic and episodic memory use different brain regions
• Clive Wearing has retrograde amnesia for episodic and semantic memories, but can gain new procedural memories, suggesting the three types of long-term memory are separate and use different brain areas
• Generalizing findings from idiographic clinical case studies to explain memory in the wider population is problematic, as other unknown issues unique to the individual could explain their behavior
• Working memory model


  Baddeley and Hitch 1974, a theoretical counter model of information processing that replaced the short-term memory store in the multistore model
• 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 the tasks use different processing subsystems, suggesting the phonological loop and visuospatial sketchpad are separate systems
• 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
• More brain activation is found in the prefrontal cortex when information is integrated, and in posterior regions when not integrated, suggesting the episodic buffer exists and is located in the prefrontal cortex
• The capacity of the phonological loop is limited by the time it takes to say the words, known as the word length effect
• The working memory model seems more accurate than the short-term memory component of the multistore model 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
• It is impossible to directly observe the memory processes described in models like the working memory model, so inferences and assumptions must be made that could be incorrect
• Interference theory of forgetting

  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 larger gaps between learning and retrieval)
• Cue-dependent forgetting


  Information is in long-term memory but forgetting happens due to the absence of appropriate cues or prompts encoded at the same time
• Context-dependent cues


  Aspects of the external environment that act as cues to memory
• State-dependent cues


  Aspects of the internal environment, such as emotions, drugs, or states of arousal, that act as cues to memory
• Retroactive interference


  New information disrupts old information
• Proactive interference


  Previously learned information disrupts the learning of new 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, such as sight, sound, and smells
• State dependent cues


  Aspects of our internal environment that work as cues to memory, such as emotions, drugs, and states of arousal
• 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, and the lack of organization cues inhibits memory
• Retroactive interference


  • Smith sent a questionnaire to 11 to 79 year olds, including a map of the area around their school without street names, and found that the more times an individual moved home, the fewer street names could be recalled, suggesting adding new street names to memory makes recalling old street names harder
• Proactive interference


  • Greenberg and Underwood found that the number of correctly recalled word pairs decreased the more word pairs had been learned previously, suggesting the previously learned word combinations cause confusion in the coding of the later word lists