duration

• STM duration (Peterson&Peterson) - procedure

  each student given consonant syllable to remember

  student told to count backawards and told to stop after 3, 6, 9 ,etc seconds
• STM duration (Peterson&Peterson) - findings

  after 3 seconds recall was 80% accurate

  after 18 seconds reacll was 3% accurate

  STM duration 18 seconds
• LTM duration (Bahrick) - photo recognition 


  people asked to remember people based on photos

  after 15 years - 90% accurate

  after 48 years - 70% accurate
• LTM duration (Bahrick) - free recall 


  people asked to recall people names from memory

  after 15 years - 60% accurate

  after 48 years - 30% accurate
• LTM duration is for a

  lifetime
• peterson&peterson - external validity

  P: limitation - peterson&peterson's study didn't use meaningful material

  E: we do try to remember meaningless material such as phone numbers

  E: however consonant syllables do not reflect everyday memory tasks at all

  L: therefore study lacks validity
• bahrick's study - external validity 


  P: bahrick's study has high external validity

  E: researchers investigated meaningful memories

  E: studies conducted on LTM with meaningless pictures to be remembered led to less accurate recall rates

  L: therefore bahrick's findings reflect a more 'real' estimate of LTM duration