Coding, capacity, duration

• Coding

  The format in which information is stored
• Who did research on coding?

  Alan Baddeley (1966)
• Process of Baddely's Experiment on coding

  Group 1 - Accoustically similar

  Group 2 - Acoustically disimilar

  Group 3 - Semantically similar

  Group 4 - Semantically disimilar

  They were given a list of original words in wrong order. Had to recall in correct order. (LTM 20 Min Interval)
• Results of Result of Baddley's Experiment For coding in STM

  • Confusion between acoustically similar words (acoustic confusion)
  • STM is therefore coded acoustically
• Conclusions for Baddeley's Experiment on codingLTM - Semantic confusion, coded semantically

  STM - Acoustic confusion, coded acoustically
• What is Capacity?

  Amount of information that can be held.
• Method for Jacob's Study on capacity ()

  Aim - See how much info STM can hold at one time

  Developed a technique - Digit Span

  Research gave a certain number of digits then the PP recalled in correct order. If recalled correctly, amount of digits increased. Determines individuals digit span.
• Results of Jacob's Study on capacity

  7.3 letters9.3 words
• What Did Miller's Study Discover?

  The unit of information can be increased by chunking (grouping information together instead of keeping it individually)
• What is Miller's Magic Number?

  7 +/- 2

  = 5 to 9 chunks
• What is Duration?

  Length of time information can be held
• Who Conducted STM Duration Research?

  Peterson and Peterson (1959)
• Method for Peterson and Peterson's study on duration in STM

  Each student was given a nonsense triagrams (3 consenants), as well as a 3 digit number. The student had to count backwards from this number (prevents mental rehearsal) told to stop counting at different intervals.
• Results for Peterson and Peterson's Study on duration

  Amount recalled correctly:3 seconds - 90%

  18 seconds - 5%(Significant difference between them)
• Conclusion for Peterson and Peterson's study on duration

  STM has a very short duration unless it is rehearsed (e.g. mental rehearsal)
• Who Did a Study on Long Term Duration?

  Bahrick et al.
• Method of Bahrick's Study

  400 American PPs aged 17-74

  Y/O.Recall was tested:

  Photo Recognition - School year book pictures

  Free Recall - Names of people graduating in their class.
• Results of Bahrick's Study

  15 years of leaving - 90% in both correct

  Up to 48 years (correct): 80% names70% faces
• Conclusions from Bahrick's Study

  LTM can last a very long time, potentially a lifetime
• How is STM Coded?

  Mainly Acoustic
• Capacity of STM?

  7 +/- 2 (5-9)
• Duration of STM?

  Max 30 seconds
• How is the LTM Coded

  Mainly Semantically
• Capacity of LTM?

  Huge
• Duration of LTM

  Very long time - Lifetime?
• Limitation of Baddeley's study (AO3)

  • Artificial stimuli, lacks mundane realism
  • Word lists had no meaning to participants and used trivial material based off of basic word lists
  • May lack generalisability as memory is more complex than this with our constant recall and learning of more meaningful information
  • It's likely we also use semantic coding even for STM (such as street names we associate meaning to)
  • Therefore may have oversimplified the coding of STM and therefore cannot account for the more complex processing of memory
• Limitations of Jacobs and Miller with STM capacity

  • Lacks validity, Jacobs research was conducted in 1887
  • Lacked adequate control over variables, therefore some ppts may have been distracted affecting performance and therefore findings
  • Lack of control over confounding variables
  • Additionally Cowan revised Miller's research and found evidence to suggest an overestimation of STM capacity
  • Only 4 chunks, alternative to the 5-7
• Limitation of Petersen and petersen (AO3)

  • Artificial stimuli, lacks mundane realism
  • Trying to memorise consonant syllables is not typical of how STM is used on a day to day basis
  • May therefore lack external validity as it does not represent meaningful information
  • However not entirely irrelevant as it may be typical of us trying to memorise phone numbers
• Strength of Bahrick et al (AO3)

  • Real life memories were studied therefore high ecological validity as its representative of how memory (LTM) may be used in real life situations
  • Shepard found in LTM studies the use of meaningless pictures to test recall led to a decline in recall rates
  • Therefore tackles this
• Limitation of Bahrick et al, LTM duration(AO3)

  • Confounding variables cannot be controlled
  • E.g. ppts may have looked at yearbook photos and rehearsed their memory over the years
  • Additional variables such as age, physical health and memory capability may also account for findings such as older people typically having a worse memory/recall