DURATION:

• LIMITATION:

  • PETERSON AND PETERSON stimulus material was artificial

  The study is not completely irrelevant because we do sometimes try to remember fairly meaningless material (e.g. phone numbers). Even so, recalling consonant syllables does not reflect most everyday memory activities where what we are trying to remember is meaningful.

  This means the study lacked external validity.
• STRENGTH:

  One strength of Bahrick et al's study is that it has high external validity.

  This is because the researchers investigated meaningful memories (i.e. of people's names and faces). When studies on LTM were conducted with meaningless pictures to be remembered, recall rates were lower (e.g. Shepard 1967).

  This suggests that Bahrick et al's findings reflect a more 'real' estimate of the duration of LTM.