coding, capacity and duration

• Baddeley research on coding

  • participants were given 4 word sets (acoustically and sematically similar and dissimilar
  • independent groups
  • STM RESULTS:participants in group who had to recall immediately had difficulty recalling acoustical similar words
  • LTM results: in group where recall was 20 mins delayed, had difficulty recalling semantically similar words
  • CONC: STM is coded acoustically - similar sounding words
  • LTM is coded semantically - words meaning the same
• Baddeley coding research strengths

  • supports the MSM
  • evidence for separate memory stores
  • identified STM and LTM
• Baddeley coding research limitations

  • low ecological validity - lab setting (artificial stimuli)
  • didn't test all LTM forms: didn't test for procedural or episodic LTM
• Jacobs' capacity research

  • capacity of STM
  • lab experiment
  • participants had to recall a sequence of letters or digits in the right order
  • repeated procedure until they couldn't recall accurately
  • span of memory and chunking helps recall
  • could recall 9-3 digits and 7-3 letters
• Miller capacity research

  • what he suggested to Jacobs' research
  • span of memory and chunking
  • 5-9 items
  • putting items together extends STM capacity
• Jacobs' capacity research strength

  • a valid study
  • later studies by BOPP replicated findings so it was a valid test of digit span
• Miller captain research limitation

  • not so many chunks
  • he overestimated STM, only 4 chunks (COWAN)
• Peterson and Peterson duration research

  • duration of STM
  • 34 students to recall combinations of 3 letters (trigrams) after linger and longer intervals
  • during intervals they were prevented from releasing by a counting task
  • RESULTS: the longer they had to count, the less they were able to recall accurately
  • after 3 secs, 80% was recalled correctly
  • after 6 secs, 50%
  • after 18 secs, less than 10%
  • STM has a limited duration of 18 seconds without rehearsal
• Bahrick duration research

  • LTM duration
  • yearbooks face recognition and name recall
  • 90% face recognition and 60% name recall after 15 years
  • 70% face recognition and 30% recall after 48 years
• Peterson and Peterson duration research limitation

  • meaningless stimuli in STM study
  • Peterson's used consonant syllables
  • lacks external validity
• Bahrick duration research strength

  • high external validity
  • used meaningful materials, better recall than studies with meaningless stimuli (Shepard)
• sensory memory coding

  • iconic memory - visual sensory memory reigster
  • echoic memory - auditory information - sensed by the ear hair cells and processed after in the temporal lobe
• what is free recall?

  where participants study a long word list the recall as many as possible in any order
• Sensory memory coding, capacity and duration


  CODING: modality specific

  CAPACITY: unlimited

  DURATION: 250 milliseconds
• short term memory coding, capacity and duration


  CODING: acoustic

  CAPACITY: 5-9 items

  DURATION: 18-30 seconds
• long term memory coding, capacity and duration


  CODING: semantic

  CAPACITY: unlimited

  DURATION:unlimited