CAPACITY, DURATION AND CODING

• What is memory?


  The process by which we retrieve and retain information from the past.
• What are the two types of memory?

  Short-term memory and long-term memory.
• What is coding?


  The way information is processed into memories.
• What is storage?


  The ability to retain information. Has limited duration and capacity.
• What is retrieval?


  Assessing information stored in memory.
• What is capacity?


  The amount we can store.
• What is duration?


  The length of time we can store.
• What is coding/encoding?


  The way information is processed by the store.
• Coding in short term = 7+/-2

  Coding in long term = unlimited
• Duration in short term = 18-30 seconds

  Duration in long term = unlimited
• Coding in short term = acoustically

  Coding in long term = semantically
• Research for STM duration:

  Peterson and Peterson (1959)- consonant trigram

  Asked to recall the trigram of 3 letters after counting backwards in threes to prevent rehearsal after 3, 6, 9, 12 seconds etc.

  Highest level of real was after 3 seconds (90%) but this decreased rapidly - 2% after 18 seconds.
• Research for STM capacity:


  Miller (1956) - digit span technique

  reading a series of digit sets that get gradually longer. participant is asked to repeat set immediately in the right order
• Research for LTM duration:

  Bahrick et al (1975) - asked 392 17-74 year olds to name old classmates from high school photos(free recall); given 50 photos and asked if they remember their classmates (recognition)

  Found that 25 years after graduation, free recall was 60% accurate. after 48 years this dropped to 30%

  Recognition was 90% after 25 years, dropping to 70% after 48 years.
• Research for STM coding:


  Baddeley (1966) - present list of words that were acoustically similar and asked for immediate recall.

  Made more errors than if they were presented with acoustically different words

  Confusion based on sound.
• Research for LTM coding:

  Baddeley (1966) - presented words that were semantically similar and asked for recall 20 mins later

  Made more errors than when they were presented with semantically different words

  Confusion over meaning of words
• Murdock (1962)

  presented ppts with a list of words and asked to recall as many as possible

  found the highest recall with the words at the beginning of the list (primacy effect) and at the end of the list (recency effect)

  words in the middle of the list were lost due to a lack of rehearsal.
• Baddeley (1966)

  gave 4 different groups of ppts 4 word lists that were acoustically similar, acoustically different, semantically similar and semantically different.

  ppts had to put the words on the correct order, either immediately(ST) or after a delay (LT).

  in ST, they made more mistake on the acoustically similar list

  in LT, they made more mistakes on the semantically similar list

  suggests the STM is acoustically encoded (sound), and LTM is semantically encoded (meaning).