LTM

• Duration of LTM

  Harry Bahrick and colleagues (1975) studied 392 participants from the American state of Ohio who were aged between 17 and 74. High school yearbooks were obtained from the participants or directly from some schools..
• Recall was tested in various ways, including: (1) photo-recognition test consisting of 50 photos, some from the participants high school yearbook; (2) free recall test where participants recalled all the names of their graduating class.
• Participants who were tested within 15 years of graduation were about 90% accurate in photo recognition. After 48 year, recall declined to about 70% for photo recognition.

  Free recall was less good than recognition. After 15 years this was about 60% accurate. dropping to 30% after 48 years.
• Conclusion:

  -This shows that LTM can last a very long time indeed.
• Strength:

  -Strength of the research is that it used real life memories.

  -For example, ppts were asked to recall the names of their graduating class through looking at a photo and through free recall. This is seen as a realistic task as we can carry this out in real life.

  -This suggests there is high external validity, as the study can be generalised to real life situations.
• Weakness:

  -There was problems with confounding variables.

  -For example, the study was a natural experiment. The IV (time since the ppts graduated) occurred naturally and Bahrick looked to see how this affected the DV (accuracy of memory recall).

  -Confounding variables such as friendships with old classmates may have affected how they could remember.

  -This suggests that the study lacks internal validity, as the individual differences could have affected the accuracy of memory recall.