coding, capacity, duration

• STM retrieval

  Only possible immediately
• Research on coding(AO1)

  -Baddeley gave different lists of words to four groups of participants

  -participants asked to recall them in the correct order

  -when recalling from STM they did worse with acoustically similar words

  -when recalling from LTM (after 20 mins) they did worse with semantically similar words

  -suggests STM codes acoustically and LTM semantically
• Research on duration (LTM)AO1

  -bahrick studied American participants

  -did a photo recognition and free recall test

  -within 15 years of graduation about 90% accuracy in photo recognition, 60% in free recall

  -after 48 years accuracy in photo recognition was 70% and 30% for free recall
• STM

  -acoustic

  -limited (7+/- 2 items)

  -up to 30 seconds
• Research on duration (STM)AO1

  -Petersons tested students

  -given a constant syllable and 3 digit number which they counted backwards from

  -this prevented mental rehearsal

  -after 3 seconds average recall was 80%

  -after 18 seconds it was 3%

  -suggests STM duration is around unless we repeat the info over
• Research on capacity (miller)AO1

  -span of memory and chunking

  -made observations of everyday practice

  -noted things come in sevens e.g. days of the week

  -thought capacity of STM is about 7+/- 2 items

  -recall words as easy as letters by chunking
• Research on capacity (Jacob's digit span)AO1


  -jacobs read out four digits, if the participants recalled them in the correct order five would be read out etc

  -mean span for digits across all participants was 9.3 items

  -mean span for letters was 7.3
• LTM retrieval

  Possible at any time, info may be different each retrieval, can use links to other material to retrieve
• LTM

  -semantic

  -unlimited

  -from minutes to years
• Strength of research into coding (AO3)

  -baddeleys study identified a clear difference between two memory stores 

  -the idea that STM mostly codes acoustically and LTM codes semantically has stood the test of time 

  -an important step in to understanding of the memory system and led to the MSM
• Limitation of research into coding (AO3)

  -baddeleys study used quite artificial stimuli 

  -word lists had no personal meaning to participants  so findings might not tell us much about coding in everyday life 

  -this suggests that the findings from this study have limited application 
• Strength of research into capacity (AO3)

  -Jacob's study has been replicated 

  -his findings have been confirmed by other better controlled studies 

  -suggests Jacob's study is a valid test of digit span in STM
• Limitation of research into capacity (AO3)

  -miller may have overestimated STM capacity 

  -Cowan reviewed other research and concluded the capacity of STM is only about 4 +/- 1 chunks 

  -this suggest the lower end of millers estimate is more appropriate than the 7 items
• Limitation of research into duration (AO3)

  -the Peterson used stimulus material that was artificial 

  -recalling consonants doesnt reflect most everyday memory activities as its not meaningful 

  -this means the study lack external validity 
• Strength of research on duration (AO3)

  -Bahricks study has high external validity 

  -the researchers investigated meaningful memories, when LTM studies were conducted with meaningless pictures recall rates were lower 

  -this suggests the findings reflect a more real estimate of the duration of LTM