Question | Answer |
Capacity and encoding | Joseph Jacobs (1887) George Miller (1956) Simon (1974) Cowan (2001) Baddeley (1966a and 1966b) Brandimote et al (1992) Wickens et al (1976) Frost (1972) Nelson and Rothbart (1972) |
Capacity of STM - Joseph Jacobs (1887) | Serial digit span task AIMS: To investigate the capacity of STM PROCEDURE: String of digits in a separate box. Cover all except the first and say the digit, shut your eyes and then recall. Repeat with looking at two digits and so on. Keep going until they are not recalled correctly FINDINGS: Average span for digits was 9.3 items, while it was 7.3 for letters. Recall increases steadily with age (8 year olds - 6.6 digits, 19 year olds - 8.6 digits) CONCLUSION: STM capacity is about 8 items, digits are easier o remember as there are only 9 of them, whereas there are 26 letters. Gradual increase in brain capacity. People develop strategies to improve memory (e.g. chunking) EVALUATION: Low ecological validity - participants are recalling numbers is not an everyday occurrence. Validity issue - only using numbers to measure. Conflicting evidence. Individual differences. |
Increasing the capacity of STM - George Miller (1956) | 'The magic number seven plus or minus two' AIMS: To investigate the span of immediate memory. PROCEDURE: Reviewed psychological research into the span of immediate memory FINDINGS: People can cope reasonably well with counting seven dots flashed onto a screen but not many more than this. The same with musical notes, digits, letters and words. People can recall 5 words as well as they can recall 5 letters. CONCLUSION: The span of the immediate memory is 7(+/-2). We chunk things together and can then remember more. EVALUATION: Individual differences - some people can remember more than others. Real world applications - can be used to remember post codes and telephone numbers. Miller did not specify the size of the chunk - does this affect the recall? |
Increasing the capacity of STM - Simon (2001) | The size of the chunk matters AIMS: To investigate whether the size of a 'chunk' affects the recall. FINDINGS: People had a shorter memory span for larger chunks , such as 8-words phrases, than smaller chunks, such as one-syllable words CONCLUSION: The size of a chunk matters when recalling. |
The capacity of STM may be even more limited - Cowan (2001) | Capacity of STM AIMS: To review the capacity of STM. PROCEDURE: Reviewed a variety of studies on the capacity of STM. FINDINGS: STM may not be as extensive as first thought. CONCLUSION: STM is limited to about 4 chunks |
Encoding in STM and LTM, acoustic and semantic encoding - Baddeley (1966a and 1966b) | Acoustic and semantic encoding AIMS: To compare the ways information is stored in STM and LTM in terms of encoding and memory trace. To test the effects of acoustic and semantic similarity on ST and LT recall. PROCEDURE: Gave participants a list of words which were acoustically similar or dissimilar and words that were semantically similar or dissimilar. FINDINGS: Participants had difficulty remembering acoustically similar words in STM but not in LTM, whereas semantically similar words posed little problem for ST recall but led to muddled LTMs. CONCLUSION: Encoding is acoustic or visual in STM and semantic in LTM. EVALUATION: High ecological validity as they are words we would use, but also a low ecological validity as words do not organise themselves naturally like this. Independent measures design is reducing order effects. |
Brandimote et al (1992) - LTM and STM may sometimes use other codes | Procedure: Participants were given a visual task (pictures) and prevented from doing any verbal rehearsal in the retention interval (they had to say 'la la la') before performing a visual recall task. Findings: participants used visual encoding in STM |
Wickens et al (1976) Frost (1972) Nelson and Rothbart 1972) | Wickens et al (1976) STM sometimes uses a semantic code Frost (1972) Long-term recall is related to visual as well as semantic categories. Nelson and Rothbart (1972) Found evidence of acoustic encoding |
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