Duration

• Definition

  The length of time information can be held in memory.
• Peterson and Peterson - procedure

  • Present participants with a consonant trigram (eg: YTG).
  • Participants count backwards from a 3 digit number for interval various seconds.
  • Participants then asked to recall the trigrams.
• Peterson and Peterson - findings

  • 80% correct recall after 3 second interval
  • 3% correct recall after 18 second interval
• Peterson and Peterson - conclusion

  STM duration is about 18 seconds unless we rehearse it.
• Bahrick - procedure

  392 graduates tested (aged 17-74) on their ability to:

  • Recognise classmates pictures (from 50 photos)
  • Match names to pictures
  • Recall names with no picture clue
• Bahrick - findingsand conclusion

  • Participants performed well up to 34 years since graduation, better on recognition than recall.
  • Dip in performance after 47 years since graduation.
  • 90% accurate in photo recognition after 15 years, 70% after 48 years.
  • 60% accurate free recall after 15 years, 30 after 48 years.

  Conclusion:

  • The duration of LTM is extensive
• Strength - external validity - Bahrick

  • Researchers investigated meaningful memories.
  • Reflects a more realistic estimate of the duration of LTM.
• Limitation - Peterson and Peterson - artificial stimuli

  • Did not use meaningful material - doesn't reflect everyday life situations.
  • Study lacked external validity.