duration

• what is duration

  the length of time info can be held in memory
• the research - STM

  • Peterson and Peterson (1959) - tested 24 undergrads and each took part in 8 trials.
  • on each trial they were given a triagram (eg. YCB) and a 3-digit number
  • they were asked to count backwards from the number to prevent rehersal
  • on each trial they were told to stop after different periods of time, (3, 6, 9, 12, 15, or 18 seconds). the less time they spent counting, the higher recall was
  • this suggests that the duration of STM is very short unless we use rehersal
• the research - LTM

  • Bahrick et al (1975) studied 392 ppts, aged 17-74
  • their recall was tested through their yearbooks, either a photo-recognition test or free-recall
  • when tested within 15 years of graduating, 90% accuracy in photo recognition and 60% accuracy in free recall
  • when tested within 48 years, 70% accuracy in photo recognition, and 30% free recall
  • this shows that LTM can last a very long time
• evaluations

  1. METHOD (limit)Peterson+Peterson STM - stimuli was artificial
  2. METHOD (strength) Bahrick LTM - high external validity as real-life meaningful memories were studied