Coding, capacity and duration

• Research on coding

  Alan Baddeley 1966 -

  4 word groups : acoustically similar, acoustically dissimilar, semantically similar, semantically dissimilar
• Baddeley

  Participants when recalling STM did worse on acoustically similar words

  Participants when recalling LTM did worse on semantically similar words
• Baddeley conclusion

  Information is coded acoustically in STM and semantically in LTM
• Digit span - Joseph Jacobs (1887)


  Researcher reads 4 digits and participants recall, then 5 and so on until participant can no longer recall
• Span of memory and chunking - George Miller (1956)


  Miller noted things in the world come in 7s

  He thought STM span was 7 +/- 2

  He noted that 5 words is as easy to recall as 5 digits

  This is due to chunking of information
• Duration of STM

  Margaret and Lloyd Peterson (1959)

  Student given a consonant then a counting task to stop mental rehearsal

  After 3s recall was 80%

  After 18s recall was 3%

  Suggests STM duration was 18s

  More if mental rehearsal is allowed
• Duration of LTM - Bahrick (1975)


  Photo and free recall of names from highschool yearbook

  Participants ages 17-74

  Within 15 years - 90% photo, 60% free

  After 48 years - 70% photo, 30% free