Duration

• Duration

  This is HOW LONG it can store information for
• STM - Peterson and Peterson, 1959

  They tested 24 undergraduates. They were given a trigram (e.g. YMA) and a 3 digit number to count back from. They had different retention intervals (3 seconds, 18 seconds, 30 seconds).

  Strength:

  • reliability - standardised procedures meant it could be replicated (all PPs given trigrams and same intervals)

  Weakness:

  • external validity as stimuli was artificial
• Petersons' findings

  • the duration of STM is 18-30 seconds
  • 80% retention at 3 seconds, 3% at 18 seconds (of their 24 undergraduates)
• LTM - Bahrick et al, 1975

  There were 392 PPs and their recall was tested using photo yearbooks (of their schools) and free recall of names.

  Strength:

  • external validity - tested memory in a way in which it would be used in a normal environment

  Weakness:

  • reliability - there was a lack of control as they did not ask if they had been in contact with any of their classmates prior to the study taking place
• Bahrick's findings

  • LTM's duration is 'a very long time' - up to a lifetime
  • 15 years since graduation, photo recognition was 90% accurate and after 45 years it was 70% accurate
  • After 15 years, free recall was 60% accurate and after 45 years it was 30% accurate