Coding, capacity, duration

• what is schema?


  A schema is a cognitive framework or mental structure that helps organize and interpret information.
• what is inference?


  Drawing conclusions or making predictions based on evidence or reasoning.
• what is an example of schema?

  Based on prior experience we might develop a schema for riding on the bus. We know what to expect. For eg, we pay the driver, we find a seat, we ring the bell when we want to get off.
• what is the purpose of schema?

  Schema enable us to process lots of information quickly, providing us with mental shortcuts and stopping us from feeling overwhelmed by stimuli. However they can distort information, which can lead to errors in perception.
• what is machine reductionism?

  Explaining the complexity of the human mind using a simple computer analogy.
• why is machine reductionism a weakness of the cognitive approach?
• why is machine reductionism a weakness of the cognitive approach?

  The computer analogy (an example of machine reductionism) ignores the influence of human emotion and motivation on the cognitive system. Anxiety can affect eyewitness memory. 
• how is short term memory coded?

  acoustically
• how is long term memory coded?

  semantically
• what is the capaity of stm?

  7+/- 2 items
• what is the capacity of ltm?

  unlimited
• what is the evidence of stm coding?

  Baddeley - word recall of similar/dissimilar words
• what is the evidence of ltm coding?

  Baddeley - word recall of similar/dissimilar words
• what is the evidence of stm capacity?

  Jacobs - Digit Span 

  ( 9.3 digits / 7.3 letters)

  Miller - Chunking items together extends STM capacity 

  (7+/-2)
• what is the duration of stm?

  18-30 seconds
• what is the evidence of the stm duration?

  Peterson & Peterson - Trigrams 

  (18 seconds without rehearsal)
• what is the duration of ltm?

  a lifetime
• what is the evidence for ltm duration?

  Bahrick - Yearbook: face recognition 90%; free recall 60% (15 ys).

  Face recognition 70% free recall 30% (48 yrs)
• Baddeley's study into coding

  • Established a clear difference between two memory stores
  • Short-term memory and long-term memory were separate stores due to the information being coded differently
• Coding in short-term memory vs long-term memory

  • STM coding is acoustic
  • LTM coding is semantic
• Participants struggled to remember acoustically similar words immediately after recall (STM)


  Participants had difficulty remembering semantically similar words 20 minutes later (LTM)
• Baddeley's study into coding was an important step towards understanding the memory system which led to the multi-store model
• evaluation of coding

  P: One limitation of Baddeley’s study into coding is that artificial stimuli was used as opposed to meaningful material.

  Ev: For example, the words used as stimuli (e.g. cat, cab, can etc.) were meaningless to the participants.

  Ex: This limits the ecological validity of the study given the fact that it does not replicate memory tasks which would be experienced as part of everyday life; if the words were meaningful then the STM would potentially use semantic coding too.

  L:This suggests that findings from Baddeley’s study are somewhat limited in application.
• evaluation of capacity

  P: One strength of Jacobs’ study is that it has been replicated.

  Ex: Although Jacobs’ (1887) study was an old one which may have lacked adequate controls. For example, some pps may have been underestimated because they could have been distracted during the test (lack of control of variables).

  Ev: However, Bopp and Verhaeghen (05) was a better controlled study and this replication is one of many that has successfully been replicated and confirmed the results of Jacobs (1887). 

  L: This suggests that Jacobs’ study is a valid test of digit span in STM.
• evaluation of capacity

  P: One limitation of Miller’s (1956) research is that the capacity of the short-term memory may have been overestimated. 

  Ev: Cowan (2001) reviewed other research and concluded that the capacity of STM is only about 4 (+/- 1) chunks.

  Ex: This contradictory research has led to a review of the capacity of short-term memory.

  L: This suggests that the lower end of Miller’s estimate (five items) is more appropriate than seven items.
• evaluation of duration

  P: One limitation of Peterson & Peterson’s study is that the stimulus material was artificial.

  Ev: In the study, pps were asked to recall consonant trigrams such as CPW, NPV.

  Ex: The recalling of consonant syllables does not reflect everyday memory tasks and so is not considered to be a meaningful test of memory.

  L: This means that the study lacked external validity.
• evaluation of duration

  P: One strength of Bahrick et al.’s study is that it has high external validity. 

  Ev: This is because the researcher’s investigated meaningful memories (i.e. of people’s names and faces).

  Ex: When studies on LTM were conducted with meaningless pictures to be remembered, recall rates were lower (e.g. Shepard, 67).

  L: This suggests that Bahrick et al.’s findings reflect a more ‘real’ estimate of the duration of LTM.