AQA A-level Psychology - Memory

• Capacity


  A measure of how much can be held. It's represented in terms of bits of information, such as number of digits
• Coding


  The way information is changed so it can be stored in memory. Information enters the brain via the senses. It is then stored in various forms, such as visual codes (pictures), acoustic codes (sounds) or semantic codes (the meaning of the experience)
• Duration


  A measure of low long a memory lasts before it is no longer available
• LTM


  Memory for events that have happened in the past. This lasts anywhere from 2 mins to 100 years. LTM has potentially unlimited duration and capacity and tends to be coded semanticaly
• STM


  Memory for immediate events. STMs are measured in seconds and mins rather than hours and days - they have a short duration. They disappear unless they are rehearsed. STM also has a limited capacity of about 4 items or chunks and tend to be coded acoustically. This type of memory is sometimes referred to as working memory
• What did Jacobs (1887) study?

  STM capacity
• Jacobs (1887) - Procedure

  Jacobs used a sample of 443 female students (aged from 8-19) from the North London Collegiate School. Participants had to repeat back a string of numbers or letters in the same order and the number of digits/letters was gradually increased, until the participants could no longer recall the sequence.
• Jacobs (1887) - Findings

  Average span was 9.3 digits and 7.3 letters
• Why might it be easier to remember more numbers?

  Because there are only 9 numbers whereas there are 26 letters
• What did Miller (1956) study?


  Capacity of STM
• Miller (1956) - Findings


  The magic number (7+-2)

  People could remember 5 letters as well as they could remember 5 words

  We chunk things together and then can remember more
• Strengths of research into the capacity of STM

  - Jacobs (1887) supports Miller's conclusions with his research

  - Simon (1974) found that people have a shorter memory span for larger chunks such as 8 word phrases, than smaller chunks such as 1 syllable words - supports the idea that STM capacity is limited
• Limitations of research into the capacity of STM

  - Cowan (2001) reviewed a variety of studies on the capacity of STM and concluded that it is likely to be limited to 4 chunks

  - Jacobs (1887) found that recall increased with age - mean digit recall for 8 year olds was 6.6 whereas average recall for 19 year olds was 8.6. This increase could be because of development of skills such as chunking
• Who studied the duration of STM?

  Peterson and Peterson (1959)
• Peterson and Peterson (1959) - Procedure

  24 student participants

  Tested over 8 trials

  Each participant given a constonant syllable and a 3-digit number

  Asked to recall the syllable after a retention interval of 3,6,9,12,15 or 18 seconds

  During retention interval they had to count backwards from their 3-digit number
• Peterson and Peterson (1959) - Findings

  90% correct after 3 seconds

  20% correct after 9 seconds

  2% correct after 18 seconds
• Peterson and Peterson (1959) - Conclusions

  STM has a very limited duration - less that 18 seconds - as long as verbal rehearsal is prevented
• Who studied the duration of LTM?

  Bahrick et al. (1975)
• Bahrick et al. (1975) - Procedure


  400 participants aged 17-74

  Photo recognition test consisted of 50 photos, some from the participants high school year book

  In a free recall test, participants were asked to recall the names they could remember of those in their graduating class
• Bahrick et al. (1959) - Findings


  Participants tested within 15 years of graduation were about 90% accurate in identifying faces

  After 48 years, this declined to about 70% for photo recognition

  Free recall was about 60% accurate after 15 years

  Dropped to 30% after 48 years
• Strengths of research into the duration of STM

  - study does have some relevance to everyday life when we try to remember postcodes or phone numbers
• Limitations of research into the duration of STM

  - task was artificial

  - results may be due to displacement as participants were counting the numbers in their STM which may displace the syllables

  - Reitman (1974) used auditory tones instead of numbers so that displacement wouldn't occur and found that duration of STM was longer
• Strengths of research into the duration of LTM

  - High ecological validity as the study used real life memories
• Limitations of research into the duration of LTM

  - Lack of population validity and generalisability because the sample are all American and students

  - Unable to explain whether long-term memory becomes less accurate overtime because of a limited duration, or whether long-term memory simply gets worse with age. This is important because psychologists are unable to determine whether our long-term memory has an unlimited duration (like the multi-store model suggests), which is affected by other factors, such as getting old, or whether our long-term memory has a limited duration.
• Who studied the coding of STM and LTM

  Baddeley (1966)
• Baddeley (1966) - Procedure


  75 participants

  Presented with 4 word lists: Acoustically similar, acoustically dissimilar, semantically similar, semantically dissimilar. STM testing assessed recall immediately after. LTM testing assessed recall after 20 minutes of a distraction task.
• Baddeley (1966) - Findings


  STM - acoustically similar performed worst, therefore most confusion, therefore coding is acoustic

  LTM - semantically similar performed worst, therefore most confusion, therefore coding is semantic.
• Strengths of Baddeley's research into coding

  - Study is standardised to can be easily replicated
• Limitations of Baddeley's research into coding

  - Brandimore et al. (1992) found participants used visual coding in STM if given a visual task (pictures) and prevented from doing any verbal rehearsal in the retention interval (they had to say 'la la la') before performing a visual recall task

  - Frost (1972) showed that long-term recall was related to visual and semantic categories

  - Nelson and Rothbart (1972) showed evidence of acoustic coding in LTM

  - Did he really test LTM because participants only waited 20 mins
• Who came up with the MSM?

  Atkinson and Shiffrin (1968)
• What is the sensory register?

  A short duration store that holds information we have gained through the 5 senses
• Why is attention necessary?

  To transfer information into the STM
• What is the role of STM in the MSM?

  Information is held in the STM so it can be used for immediate tasks
• What is maintenance rehearsal?


  Repeating information over and over to hold it in STM longer

  Research has found a direct correlation between rehearsal in STM and strength of LTM
• What is the importance of LTM the MSM?

  It's potentially unlimited duration and capacity means information won't be forgotten or decay
• What is retrieval?


  Getting information from the LTM which involves it passing back through STM so it is available for use
• Strengths of the MSM?

  - Research support from HM who had his hippocampus removed on both sides to correct his severe epilepsy. His personality and intellect remained intact but he couldn't form mew LTMs but he could recall old LTMs

  - Beardsley (1997) found that the prefrontal cortex was active in STM but not LTM so they are separate stores

  - Controlled lab studies showed a difference between STM and LTM
• Limitations of the MSM

  - The model is over-simplified. It assumes that each of the stores works as an independent unit.

  - The model does not explain memory distortion.

  - The model does not explain why some things may be learned with a minimal amount of rehearsal. For example, once bitten by a dog, that memory is quite vivid in spite of the lack of rehearsal.

  - There are several times that we rehearse a lot to remember material and it is not transferred to LTM.

  - KF remebered auditory stimuli more than visual stimuli suggests that the MSM is too simple in suggesting that STM is just one store
• Who designed the WMM?

  Baddeley and Hitch (1974)
• Central Executive


  Monitors and coordinates all other mental functions in working memory