Coding, Capacity, Duration

• What was Alan Baddeley‘s study ?

  He researched into coding of memory. He gave different lists of words to four groups of participants to remember. Participants were shown the original words and asked to recall them in the correct order
• Results of Alan Baddeley’s study

  When they had to do this recall task immediately after hearing it they tended to do worse with acoustically similar words. If participants were asked to recall the word list after a time interval of 20 minutes they did worse with the semantically similar words
• Joseph Jacob’s - digit span - procedure

  4 digits asked to recall in correct order out loud if correct researcher then reads out 5 digits and so on until the participant can’t Recall them in order correctly.
• Joseph Jacobs - digit span - findings

  The mean span for digits was 9.3 items and the mean span for letters was 7.3
• George Miller - magic number

  He noted that things come in sevens which suggests that the capacity of short term memory is about 7 items plus or minus 2
• Peterson and Peterson - procedure

  • Tested 24 undergrad students
  • Each student took part in eight trials
  • They were given a consonant syllable and a 3 digit number
  • Then asked to count backwards from that 3 digit number until told to stop
• Harry Bahrick - Procedure

  • Studied 392 participants from Ohio aged between 17 and 74
  • They got their high school yearbooks and recall was tested differently between participants
  • Photo recognition test consisting of 50 photos
  • Free recall test recalled all names of graduating class
• Harry Bahrick - findings

  • Tested 15 years after were about 90% accurate - photo
  • 48 years after recall declined to about 70% - photo
  • 15 years was about 60% accurate - free recall
  • 48 years was about 30% accurate - free recall
• Limitation of Jacob’s study

  Conducted a long time ago so lacked adequate control like how some participants may have been distracted while they were being tested so they didn’t perform as well as they might so the results might not be valid because there were confounding variables that were not controlled
• Limitation of Miller’s research

  He may have overestimated the capacity of STM. Research found that the capacity of STM was only about four chunks suggesting that the lower end of Millers estimate is more appropriate than seven items
• Limitation of Baddeley’s study

  Used quite artificial stimuli rather than meaningful material which suggests that the findings from this study have limited application
• Limitation of Peterson and Peterson‘s study

  The stimulus material was artificial so the study lacked external validity however sometimes we try to remember fairly meaningless things so the study is not totally irrelevant
• Strength of Bahrick’s study

  It has higher external validity however confounding variables are not controlled like that the participants may have looked at their yearbook photos and rehearsed their memory over the years