Research On Duration Flashcards
Study for short term memory
Margaret and Lloyd Peterson (1959)
Method for Peterson and Peterson
- Tested 24 students in eight trials each
- On each trial, students were given a consonant syllable (eg. YCG) to remember
- Then, they were given a 3 digit number which they had to count backwards from until they were told to stop.
- This backward counting was to prevent mental rehearsal.
- On each trial, they were told to stop after varying periods of time- 3, 6, 9, 12, 15 or 18 seconds (retention interval).
Results for Peterson and Peterson
After 3 seconds, average recall was 80%
After 18 seconds, average recall was 3%
Therefore, this shows that STM duration may be about 18 seconds, unless we repeat the information over and over again.
Study for Long Term Memory
Harry Bahrick et al. (1975)
Method for Harry Bahrick
- Studied 392 American participants aged between 17 and 34
- High school yearbooks were obtained
- recall tested in 2 ways: photo-recognition and free recall
Photo-recognition test
50 photos, some from yearbook. Participants who graduation 15 years ago or less, were 90% accurate. Participants who graduated 48 years or more were 70% accurate.
Free-recall test
Recalled all the names from their graduating class without any prompts. Participants who graduated 15 years ago or less were 60% accurate. Participants who graduated 48 years ago were 30% accurate.
Findings of Bahrick’s study
Suggests that LTM may last up to a lifetime for some material.
Evaluation Peterson and Peterson
- stimulus was artificial
- Isn’t completely irrelevant was we do sometimes need to remember meaningless material such as PIN codes or phone numbers
- Recalling consonant syllables does not reflect most everyday memory
- Low external validity
Evaluation of Bahrick et al.
- High external validity
- Meaningful memories were investigated.
- When LTM studies were conducted with meaningless pictures (Shepard 1967), recall rates were lower.
- Therefore, Bahrick’s findings were a more ‘real’ estimate of the duration of LTM.