Research on duration

• Research on Duration

  Duration- the length of time that info can be held in memory

  STM- Peterson & Peterson (1959) tested 24 undergrad students that each took part in 8 trials. Given a consonant syllable (trigram) e.g., YCG to remember. Then asked to count back from 3 digit number until told to stop (prevent rehearsal). Told to stop after diff retention intervals- 3, 6, 9, 12, 15, 18 seconds. 3s= 80% recalled, 18s= 3%. Shows STM may be around 18 seconds, unless rehearsed (processed into LTM)
• Research on duration 2

  LTM- Bahrick (1975) conducted a longitudinal study on 392 American ppts aged 17-74. Recall tested through: photo-recognition test from yearbook or free recall test where ppts recalled names of graduating class. Within 15 years of graduation= 90% accurate in photo recognition, 48 years= 70%. Free recall less good- 15 = 60%, 48 = 30%. Shows LTM can last a long time (sometimes a life time)
• Research on duration- evaluation

  Peterson and Peterson- stimulus material is artificial. Memorising consonant syllables does not reflect most real life memory activities (remembering something meaningful), so lacks external validity. But sometimes remember fairly meaningless things (phone numbers) so not totally irrelevant.

  Bahrick's- high external validity. Real-life meaningful memories were studied. When studies on LTM have been conducted w/ meaningless pictures, recall rates are lower (Shepard 1967). But confounding variables can't be controlled. e.g., looked at photos & rehearsed memory.