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16 Cards in this Set
- Front
- Back
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Capacity |
Measure of how much can be held in memory. |
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Duration |
Measure of how long a memory lasts before it is no longer available. |
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Coding |
The way information is changed so that it can be stored in memory. |
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The capacity of STM |
Joseph Jacobs (1887) - average span for digits 9.3 and 7.3 for letters. |
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The magic number 7 +/- 2 |
Miller (1956) Immediate memory about 7 items. People counted 7 dots flashed on a screen. People can recall 5 words as well as 5 letters - chunking, remember more. |
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Evaluation - Capacity of STM may be even more limited |
Cowan (2001) - STM limited to four chunks - suggests less extensive. Vogal (2001) - four item limit. Lower end of Miller's range. |
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Evaluation - Size of the chunk matters |
Simon (1974) - shorter memory for larger chunks. |
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Evaluation - Individual differences |
Recall increased with age, 8yrs - 6.6 digits, 19yrs - 8.6 digits. Age increase due to increase in brain capacity. People may improve digit span with strategies. |
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Duration of STM |
Peterson and Peterson (1959) - tested over 8 trials. Consonant syllable and three digit number. Recall after 3,6,9,12,15,18 seconds. Retention interval - count backwards from three digit number. 90% correct over 3 seconds, 20% over 9 seconds, 2% over 18 seconds. STM - short duration. |
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Duration of LTM |
Bahrick et al (1975) - 400 people (17-74yrs) memory of classmates. 50 photos some from high school year book. Free-recall list names of graduating class. Photo recognition - 15 yrs - 90%, 48 yrs - 70%. Free-recall - 15 yrs - 60%, 48 yrs- 30%. |
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Evaluation - Testing STM was artificial |
Doesn't reflect daily activities. Sometimes remember meaningless things. Study has some relevance to real life. |
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Evaluation - STM results may be due to displacement |
Counting numbers displaced syllables. Reitman (1974) auditory tones instead of numbers so displacement wouldn't occur. Found duration was longer. Peterson study - due to displacement rather than decay. |
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Acoustic and semantic coding |
Acoustically similar, semantically different - cat, cab, can. Semantically similar, acoustically different - great, large, big. Baddeley (1966) - difficulty remembering acoustically similar in STM not LTM. Semantically similar little problem for STM not LTM. |
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Evaluation - Baddeley may not have tested LTM |
LTM tested by waiting 20 mins. Questionable whether testing LTM. |
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Evaluation - STM may not be exclusively acoustic |
Visual codes also use in STM. Brandimote et al (1992) - translate visual imagery to verbal code - verbal rehearsal prevented - use visual codes. Wickens et al (1976) - STM sometimes uses semantic code. |
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Evaluation - LTM may not be exclusively semantic |
Frost (1972) - long-term recall related to visual categories. STM and LTM coding not simply acosutic/semantic. |
