Bahrick et al. 1975

Bahrick et al. 1975

1. Aim:

   • To investigate duration of long term memory.

2. Procedure

   • 392 Americans were studied aged between 17-74. The PPs were tested on high school year books. Recall was tested in different ways. 1)photo recognition test including 50 photos, some from high school year books. 2) free recall test when PPs recalled all the names of their graduating class.

3. Findings

   • Photo Recognition test: Within 15 years of graduation- 90% After 48 years- 70% Free recall test: 15 years- 60% 48 years-30%. This shows LTM may last up to a lifetime.

4. Evaluation: strengths and weaknesses

   • One strength of Bahrick's study is that it has high external validity. This is because the researchers investigated meaningful memories (i.e. people's names + faces). Shepard (1967) studied on meaningless pictures and recall rates were lower. This suggests his findings reflected s more "real" estimate of duration of LTM, also findings are reliable, as it has support.
   • One weakness of Bahrick's study is that researchers had poor control over the experiment. It was not recorded whether the participants were still in contact with anyone from school before they were tested or there could have been a school reunion the week before. This suggests that classmates are rarely forgotten before recognition cues are given and supports the claim of the duration of LTM. However, this study only tells us the duration of LTM for high school memories and not LTM it general, e.g, people's birthdays.
   • Another limitation of of Bahrick's study is that the findings are ungeneralisable. the study lacks population validity as the sample were all Americans and so the results may not apply to other nationalities.