memory

• Coding


  The format in which information is stored in the various memory stores and the process of converting information from one format to another as it's moved between stores
• Types of coding

  • Acoustic
  • Semantic (coding by meaning)
• Research into coding by Baddeley (1966)


  1. Participants presented with 4 lists of words

  2. Lists 1 and 2: acoustically similar or dissimilar words

  3. Lists 3 and 4: semantically similar or dissimilar words

  4. Participants had to recall the correct order of the words immediately and after 20 minutes
• Baddeley found that participants struggled most with acoustically similar words in immediate recall, concluding that short-term memory focuses too much on how the word sounds (acoustic confusion)
• Baddeley found that participants struggled most with semantically similar words in recall after 20 minutes, concluding that long-term memory gets distracted by the meaning of the words (semantic confusion)
• Baddeley's conclusions

  • Short-term memory prefers to code acoustically
  • Long-term memory prefers to code semantically
• Baddeley's findings were an important step in understanding the memory system and the creation of the multi-store model of memory
• A limitation of Baddeley's study is that it used artificial stimuli (meaningless word lists), so the findings may not apply well to memory in everyday life
• Capacity


  How much information can be held in memory at any one time
• Research on capacity of memory

  • Research by Joseph Jacobs in 1887
  • Research by George Miller in 1956
• Digit span test


  1. Researcher reads out digits

  2. Participant recalls digits in correct order

  3. Researcher increases number of digits until participant can't recall correctly

  4. Indicates individual's digit span and capacity of short-term memory
• Jacobs found digit span or capacity of short-term memory for most people was 9.3 digits or 7.3 letters
• Miller found people could roughly absorb seven new pieces of information in short-term memory at any one time
• Chunking


  Memory technique of grouping sets of digits or letters into meaningful units or chunks to make them easier to remember
• Capacity of long-term memory is considered to be unlimited
• Strength of Jacobs' study

  • It has been replicated many times and the findings have been validated
• Limitation of Miller's research

  • He may have overestimated short-term memory capacity
• Other research suggests short-term memory capacity is more like 4 plus or minus 1 chunk
• Short-term memory

  Has a limited capacity of seven plus or minus two items
• Long-term memory

  Has an unlimited capacity
• Duration


  The amount of time that information can be held for in memory
• Research by Peterson and Peterson (1959)


  • Looked at the duration of short-term memory
  • Used nonsense trigrams (3 random letters)
  • Participants had to recall trigram after a retention interval (3-18 seconds)
  • To prevent rehearsal, participants counted backwards from a 3-digit number
• • After 3 seconds, 80% of participants could recall the trigram correctly
  • After 18 seconds, fewer than 10% could recall the trigram correctly
• Conclusion: Short-term memory has a duration of 18-30 seconds
• Research by Barrick et al. (1975)


  • Looked at the duration of long-term memory
  • Used high school yearbook photos
  • Participants had to do a photo recognition task and a free recall task
• • In photo recognition task, 90% accuracy if graduated in last 15 years, 70% if graduated in last 48 years
  • In free recall task, 60% accuracy if graduated in last 15 years, 30% if graduated in last 48 years
• Conclusion: Long-term memory can last for years, if not a lifetime(unlimited)
• Multi-store model of memory

  Model of memory first proposed by Atkinson and Shifrin in 1968, suggesting memories are formed sequentially and information is passed from one component to the next in a linear fashion
• Multi-store model


  • Each component has its own type of coding, capacity, and level of duration
  • Memories are formed sequentially and information is passed from one component to the next in a linear fashion
• Coding


  The way memories are processed
• Capacity


  How much information can be held in a memory store
• Short-term memory capacity

  7 plus or minus 2 items
• Duration

  How long we can store information
• Short-term memory duration


  18 to 30 seconds
• Long-term memory duration


  Potentially unlimited
• Encoding process in multi-store model

  1. Environmental stimuli

  2. Sensory memory

  3. Short-term memory

  4. Long-term memory
• Sensory memory


  Memory for sensory information, including iconic memory for visual and echoic memory for auditory
• Sensory memory


  • Large capacity but very short duration
• Maintenance rehearsal


  Repeating information to keep it in short-term memory