• Created by: Sadia_06
  • Created on: 31-03-15 20:29

Duration Of STM

Peterson and Peterson (consonant syllables)

Aims and procedure

  • 24 students, 8 trials each
  • Consonant syllable, verbal rehearsal prevented
  • Retention interval of 3,6,9,12,15,18 seconds 

Findings and Conclusions

  • After 3 seconds, recall was about 80% 
  • After 18 seconds, recall was about 3%
  • This suggests that STM has duration of less than 18 seconds if verbal rehearsal is prevented 


  • One limitation of this study is that the stimulus material was artificial - trying to memorise consonat syllables does not reflect real life memory activites - could lack ecological validity 
  • A second limitation is that the study lacked validity because displacement may explain the findings
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Duration Of LTM

Bahrick et al - face recognition test 

Aims and procedure 

  • nearly 400 p's, aged 17-74
  • high school yearbook 
  • recognition test of faces or free recall of names 

Findings and conclusions 

  • face recogniton was 90% accurate after 15 years
  • declined to 70% after 48 years
  • free recall was 60% accurate after 15 years 


  • one limitation of this study is that rehearsal may explain their results 
  • one strength of this study is that it has high ecological validity 
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Miller - 7 +-2

Aims and procedure

  • this study is a review of other research 
  • things come in sevens
  • one STM task involved counting dots lashed on a screen 

Findings and conclusions 

  • can count 7, but not 15 dots flashed on a screen
  • suggests capacity of STM is about 7 items (+2)
  • chunking is used to increase capacity 


  • one limitation of this study is that Miller may have overestimated the capacity of STM 
  • one strength os this study is that Miller's insighs led to everyday applications 
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Capacity Of STM


Aims and procedure

  • developed digit span technique 
  • digits/letters read one at a time 
  • recall tested and then another digit added until P's can't recall correct order

Findings and conclusions

  • mean span for digits is 9.3
  • mean span for letters is 7.3
  • digit soan increased with age, possibly due to chunking 


  • one limitation of this study is that it was conducted a long time ago
  • one strength of this study is that the results are useful in confriming Miller's conclusions 
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Encoding in STM and LTM


Aims and procedures 

  • four groups (acoustically/semantically/similar/dissimlar)
  • recall was tested by placing words in right order
  • STM and LTM tested

Findings and conclusions

  • acoustically similar words remmebered worst for STM
  • semantically similar words remembered worst for LTM
  • suggests that encoding differs between STM and LTM


  • one limiation of this study was that it used quite artificial stimuli rather than meaningful material
  • another limitaion of this study is that the LTM memory task wasn't very long term 
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Multi-store Model

Atkinson and Shiffrin


  • Sensory memory, duration = milliseconds, capacity = very large 
  • attenton to items in SM leads to transfer to STM
  • STM has limited duration (measured in seconds) and capacity (about 5 chunks) and aciustic encoding
  • increasing verbal rehearsal leads to transfer from STM to LTM
  • LTM has potentially unlimited duration and capacity. Encoding tends to be semantic.


  • one strength of the MSM is that it is easy to test the predictions of the model experimentally
  • a second strength of the MSM is that further research support comes from brain scans
  • a limitation of the MSM is that it originally ignored the importance of elaborative rehearsal
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Working memory model

Baddeley and Hitch


  • WMM is a detailed explanantion of STM
  • central executive allocates slave systmes
  • phonological loop (first slave system) consists of phonological store and articulatory process
  • Visuo-spatial sketchpad (secind slave system) - stores visual/spatial information when required
  • episodic buffer (third slave system) - temporsry storage
  • dual task performance illustrates WMM


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