1. Coding capacity and duration of memory

• Short-term memory (STM) - AO1

  - Capacity - Limited between 5 and 9 items - Jacobs (1887) , Miller (1956)

  - Coding - acoustic - Baddley (1966)

  - Duration - 18 seconds - Peterson and Peterson (1959)
• Long-term memory (LTM) - AO1

  - Capacity - unlimited

  - Coding - Semantic - Baddley (1966)

  - Duration - unlimited - Bahrick et al (1975) -
• Research on coding - AO1

  Baddley (1966)
• Coding - AO1


  The format in which information is stored in the various memory stores.
• Baddley (1966) procedure - AO1

  - Gave different lists to words to four groups of participants to remember

  - Group 1 - Acoustically similar words - sound the same

  - Group 2 - Acoustically dissimilar words - sounds different

  - Group 3 - Semantically similar words - similar meaning

  - Group 4 - Semantically dissimilar words - different meanings

  - Participants were shown original words and asked to recall them in the correct order

  - When asked to the task straight away - STM - they did worse on acoustically similar words

  - When asked to the task after a time interval - LTM - they did worse on semantically words

  - Findings - Information coded for acoustically in the STM and semantically in LTM
• Baddley (1966) - AO3


  - Support for separate memory stores - 😊

  - Identified a clear difference between memory stores

  - The idea that STM uses mostly acoustic coding and LTM uses mostly sematic coding has stood the test of time

  - Allowed us to understand the memory system and led to the multi-store model of memory.

  
  

  - Artificial stimuli - 🙁

  - Uses artificial stimuli rather than meaningful material

  - The word lists had no personal meanings to participants

  - Baddley's findings may not tell us about much coding in different memory tasks - everyday life

  - When processing more meaningful information - people may use semantic coding even in STM

  - Limited application
• Research on capacity - AO1


  - Jacobs (1887)
• Capacity - AO1


  - The amount of information that can be held in a memory store
• Jacobs et al (1887) procedure - AO1

  - Researcher read out 4 digits

  - Participants were asked to recall them in the correct order

  - If recalled correctly then the researcher would add another digit

  - Until they were unable to recall in correct order

  - Findings - Mean span of digits across all participants was 9.3. The mean span for letters was 7.3
• Jacobs et al - AO3


  - A valid study - 😊

  - Replicated

  - It is a very old and early study so it may have lacked adequate controls - Confounding variables

  - Despite this - Jabob's findings have been confirmed by other more controlled studies - Bopp and Verheagan - 2005
• Span of memory and chunking - AO1

  - Miller (1956)
• Miller (1956) procedure and findings - AO1

  - Noted that things came in 7s -seven days of the week, 7 deadly sins ect

  - Noted that people can recall 5 words as easily as 5 letters

  - Chunking - grouping sets of digits or letter into units or chunks

  - Findings - Therefore the capacity of the STM was 7 items plus or minus 2
• Miller (1956) - AO3


  - Not so many chunks - 🙁

  - Millers research may have overestimated the capacity of the STM

  - Cowan (2001) - reviewed the research and concluded that the capacity of the STM was 4(plus or minus 1) chunks

  - Lower end of Millers research - five items is more appropriate that 7 items
• Research on duration - AO1

  - Peterson and Peterson (1959) - STM

  - Bahrick et al (1975) - LTM
• Peterson and Peterson (1959) procedure and findings - AO1

  - Tested 24 students in 8 trails

  - Each trail they were given a constant syllable to remember - also given a 3-digit number (986)

  - Student counted backwards from this number until they were told to stop - to prevent any mental rehearsal of the constant syllable

  - On each trail they were told to stop counting backwards after varying periods of time - either 3, 6, 9, 12, 15 and 18 seconds (The retention interval)

  - Findings - after 3 seconds average recall was about 80% and after 18 seconds' average recall was about 3%.

  - STM duration is about 18 seconds unless we repeat the information over and over (verbal rehearsal)
• Bahrick et al (1975) procedure and findings - AO1


  - Studied 92 Americans between 17 and 74

  - High school yearbooks were obtained from each participant

  - Tested recall through

  (1) Photo recognition - consisting of 50 photos where some went to the high school

  (2) Free recall test where some participants the names of their graduating class

  
  

  Findings -

  - Participants within 15 years of graduation had been

  90% - photo recognition and 60% - free recall

  - After 48 years recall declined too about

  70% - photo recognition and 30% - free recall

  - This shows that LTM can last up to a lifetime
• - Bahrick et al (1975) - AO3


  - High external validity - 😊

  - Researchers investigated meaningful memories -names and faces

  - When studies were conducted ion meaningless pictures recall rates were lower - Shepard - 1967

  - Bahrick's findings reflect a greater estimate of the duration of the LTM
• - Peterson and Peterson (1959)- AO3


  - Meaningless stimuli in STM study - 🙁

  - Stimulus material was artificial

  - Not completely irrelevant - sometimes recall long numbers - phone numbers

  - Recalling constant syllables does not reflect everyday memory activities

  - Lacks external validity