Memory

• Components of the Multi-Store Model

  • Sensory Memory (SM)
  • Short-Term Memory (STM)
  • Long-Term Memory (LTM)
• Sensory Memory (SM)


  • Capacity: unlimited
  • Duration: less than half a second
  • Encoding: 5 senses (iconic, haptic, echoic, olfactory)
• Short-Term Memory (STM)


  • Capacity: 7 ± 2 items
  • Duration: 18-30 seconds
  • Encoding: mainly acoustically
• Long-Term Memory (LTM)


  • Capacity: unlimited
  • Duration: up to a lifetime
  • Encoding: mainly semantically
• Capacity Study of Short-Term Memory

  1. Researcher gives participant digits/letters

  2. Participant recalls in correct order

  3. Researcher increases digits/letters until participant cannot recall correctly

  4. Researcher finds mean span for digits and letters
• Jacobs (1887) found the mean span for digits was 7 items and the mean span for letters was 9
• Miller (1956) suggested the capacity of STM was 7 ± 2 and introduced the idea of chunking to remember more
• Cowan reviewed research and concluded the capacity of STM is about 4 ± 1, suggesting the lower end of Miller's estimate is more appropriate
• Duration Study of Short-Term Memory

  1. Participant given trigram of letters and 3 digit number

  2. Participant counts backwards from number until told to stop

  3. Participant asked to recall trigram

  4. Recall generally accurate after 3 seconds, around 10% by 18 seconds
• Peterson & Peterson (1959) found STM fades in under a minute if rehearsal is prevented, with duration around 18-30 seconds
• Encoding Study of Short-Term Memory

  1. Participants given word lists to learn, either acoustically similar, acoustically dissimilar, semantically similar, or semantically dissimilar

  2. Participants recalled lists immediately (STM) or after 20 minutes (LTM)
• Baddeley (1966) found participants did worse with acoustically similar words in STM, suggesting STM is coded according to sound
• Duration Study of Long-Term Memory

  1. Participants shown high school yearbook photos and matched to names

  2. 90% could correctly match names and faces after 14 years, 60% after 47 years
• Bahrick (1975) found people could remember certain types of information, such as names and faces, for up to a lifetime
• Baddeley (1966) found after 20 minutes participants did poorly on semantically similar words, suggesting LTM is coded semantically
• Sensory Memory Study

  1. Participants shown chart with rows of letters for 50 milliseconds and asked to recall how many they could remember

  2. Participants could remember 4/5 letters though aware of more
• Sperling (1960) found the image of each item fades during the 50ms and the time it takes to report back recalled items
• Types of Long-Term Memory

  • Semantic Memory
  • Episodic Memory
  • Procedural Memory
• Semantic Memory


  Contains our shared knowledge of the world, includes all types of knowledge, materials are not time-stamped, less personal and more about facts we share, located in left prefrontal cortex
• Episodic Memory


  Our ability to recall events (episodes) from our lives, memories are complex and time-stamped, store information about how events relate to others in time, have to make conscious effort to recall, located in right prefrontal cortex
• Procedural Memory


  Memory for actions, skills or how we do things, recalled without conscious awareness or much effort, ability becomes automatic through practice, quite hard to explain to someone else, located in cerebellum and basal ganglia
• Clive Wearing had selective memory loss - episodic memories severely impaired, semantic memories relatively unaffected, procedural evidence still intact
• Neuroimaging evidence found episodic memories recalled from left prefrontal cortex, semantic memories from right prefrontal cortex, and procedural memories from cerebellum and basal ganglia
• Belleville demonstrated episodic memories could be improved in older people with mild cognitive impairment through training
• Central Executive (CE)


  Monitors incoming data, controls attention, allocates tasks to subsystems, responsible for reasoning and decision making, has limited capacity and can only hold one type of information at a time, codes modality free
• Phonological Loop (PL)


  Deals with auditory information and preserves the order in which we hear it, includes a phonological store that stores words we hear and an articulatory control process that allows maintenance rehearsal, capacity is what we can say in 2 seconds, codes acoustically
• Visuo-Spatial Sketchpad (VSS)


  Stores visual and spatial information, includes a visual cache that stores visual data and an inner scribe that processes the arrangement of objects, capacity is 3/4 objects, codes iconically
• Episodic Buffer (EB)


  Temporary store that integrates visual, spatial and verbal information processed by other stores, capacity is 4 ± 1 items, codes visually, spatially and verbally
• Dual Task Performance Study


  1. Participants performed a tracking task and a visual task simultaneously, or a visual and verbal task simultaneously

  2. Participants performed better when tasks were different modalities (visual and verbal)
• The dual task study supports the existence of separate VSS and PL subsystems with limited capacity
• The case of KF, who had a selective impairment to verbal STM but intact visual functioning, also supports the existence of separate VSS and PL subsystems
• fMRI Study of Central Executive

  1. Participants given tasks to complete while having their brains scanned

  2. More activation in prefrontal cortex as task demands increased
• The fMRI study provides evidence that the Central Executive may have a physical reality in the brain and has to work harder as task demands increase
• Word Length Effect and Articulatory Suppression Study


  1. Participants shown word lists and asked to write them down in order, some lists had monosyllabic words and others had polysyllabic words

  2. Participants recalled more monosyllabic words

  3. Articulatory suppression (speaking while presented with item) eliminated the word length effect
• The word length effect and its elimination by articulatory suppression supports the existence of the phonological loop in the Working Memory Model
• The case study of KF, dual task studies, and fMRI research provide clinical, experimental and neuroimaging evidence supporting the Working Memory Model
• Proactive Interference


  When an older memory interferes with a new one
• Retroactive Interference


  When a newer memory interferes with an older one
• Effects of Similarity Study


  1. Participants learned a list of adjectives until they could recall them perfectly

  2. Some participants then learned a similar list, others learned a dissimilar list
• Working Memory Model


  • Shows there must be different subsystems for visual processing (VSSP) and verbal processing (PL)
  • Lack of clarity over nature of central executive