Memory

• New information in memory is limited in capacity and duration
• Capacity is best measured in chunks
• Once information gets past that bottleneck, it is long lasting, and not limited in capacity
• Not everything gets past that bottleneck
• Divisions of Long-Term Memory


  • Explicit (Declarative) Memory
  • Implicit Memory
• Explicit (Declarative) Memory


  • Episodic- Personally Experienced & Witnessed
  • Semantic - Facts & General Knowledge
• Implicit Memory

  • Procedural (Skills) - Motor & Cognitive Habits & Conditioned Responses
  • Results of Priming
• Explicit/declarative memories


  Memories that can be consciously recalled and described
• Implicit memories


  Memories that are expressed through performance rather than conscious recollection
• Semantic memories


  General knowledge and facts about the world
• Episodic memories


  Memories of personally experienced events and episodes
• Examples of each type of memory


  • Semantic: facts about the world
  • Episodic: memories of personal experiences
  • Procedural: skills like riding a bike
  • Priming: faster identification of previously seen words
• Memory as Stages: The 3-Box Model


  Cognitive perspective/ Computer metaphor: The mind is a computer which we can understand with flow charts and programs

  
• Mnemonic devices


  Strategies that aid encoding and retrieval of information
• Elaborative strategies


  Strategies that help with encoding by connecting new information to existing knowledge
• Memory Processes


  • Encoding: Putting information in a form for storage
  • Storage: May be long or short-term
  • Consolidation: Strengthening memories for long term storage
  • Retrieval: Pulling up memories from storage
• The 3 Box Model


  • Sensory Memories: Very brief visual (or auditory) image
  • Short-term memory (STM): Limited capacity (7 +/- 2 items / chunks) & limited time
  • Long Term Memory (LTM): Not very limited in either capacity or time

  
• Sensory Memories


  • Sperling (1960) Iconic Memories: Present 3x4 array of letters, delay (blank screen), tone to signal which row to report

  
• Emotional arousal


  Affects encoding
• Sperling (1960) Iconic Memories experiment


  With delay of under 500 ms, subjects could report 3 or 4 letters

  
• Yerkes-Dodson Law


  An optimal level of arousal for encoding and retrieval
• Why could they not report the whole array? What does this imply about the nature and durability of iconic memories?

  
• Ebbinghaus forgetting curve


  Describes the rate at which memory for something fades over time
• Ebbinghaus used nonsense syllables in his experiments
• Short-term memory (STM)


  • Displacement: old items are pushed out as new items enter
  • Decay: working memory fades with time (under 30 seconds except with rehearsal)
• It is difficult to sort out forgetting from encoding failures in experiments
• Causes of forgetting


  • Storage failures
  • Retrieval failures
• Short-term memory tasks


  1. Digit span (letter span, word span)

  2. Rehearsal is the basic strategy to keep things in working memory
• Peterson and Peterson (1959) Duration of STM experiment


  With distraction of over 18 sec. subjects could not report string

  
• Poor encoding


  Makes it hard to retrieve memories
• What does this imply about the durability of STM?
• Elaborative encoding


  Helps prevent retrieval failures
• Proactive interference


  When prior learning interferes with the recall of new information
• Short-term memory is encoded, not literal. Preferred encoding for many tasks is phonological / acoustic. Error data (Conrad, 1964) shows mistakes are sound-alikes, but not look-alikes.
• Retroactive interference


  When new learning interferes with the recall of old information
• Working Memory


  In some models, substitutes for STM. Emphasizes the processes, rather than the storage space. Working memory is where information from senses and long term memory converge.

  
• Evidence for two systems (separate working memory and long term memory): Brain Activity & lesions, Case studies (e.g. E.P. damage to both hippocampi), Frontal cortex active in working memory tasks, hippocampus essential for LTM tasks

  
• Episodic memories are constructed from bits and pieces of stored information
• The serial Position Effect (Glanzer & Cunitz, 1966)


  1. Present 20 unrelated words, free recall in any order

  2. Result is U-shaped serial position curve

  3. Primacy effect: More time for rehearsal = more transfer to LTM

  4. Recency effect: Less time for decay from STM
• Variations in serial position effect


  • Speed up presentation, gives less time for rehearsal, flattens primacy effect
  • Delay recall (with distraction), allows STM to decay, flattens recency