Duration of the LTM

• LTM duration was investigated by Bahrick et al (1975):
• 392 participants aged between 17 and 74, were required to

  identify schoolmates from their high school yearbook, name them in a

  free recall test, or match photos to names.
• Participants who had left school within 15 years were very accurate

  with photo recognition (90%), but even those who had left decades

  earlier were still 60% accurate.
• Older participants (after 48 years) were less good at free recall (30%), but nearly as good as younger participants in the matching task.
• The conclusion was that the duration of LTM is potentially lifelong.
• Recall was tested in various ways, including: photo-recognition test, consisting of 50 photos, free recall test were participants recalled the names of their graduating class
• participants within 15 years of graduation were about 90% accurate in photo recognition
• after 48 years, recall declined to about 70% for photo recognition
• free recall was less accurate than recognition- about 60% after 15 years, dropping to 30% after 48 years