multi-store model of memory

• Multi-store model of memory (MSM)

  Atkinson and Shiffrin (1968): A representation of how memory works in terms of three stores:

  1. Sensory register

  2. STM

  3. LTM

  
  

  Describes how information is transferred from one store to another, how it is remembered and how it is forgotten
• Capacity


  How much can be held in a store.
• Duration


  How long information can be held in that store before loss.
• Coding


  The different information types/formats the brain uses to store memory.
• Sensory register


  A temporary storage device for holding sensory information.
• When is information passed from the sensory register to STM?

  When we pay attention to it
• Short term memory (STM)

  Memory for immediate events
• How is information transferred for STM to LTM?

  Maintenance rehearsal - repeating the information

  Elaborative rehearsal - linking to information already in LTM.
• Long term memory (LTM)

  Memory for events that have happened in the past. Information stored may last permanently.
• Features of each store

  • Coding
  • Capacity
  • Duration
• Features of sensory register

  Coding: Iconic memory store - visual information, coded visually. Echoic memory store - auditory information, coded acoustically.

  Duration: less than half a second.

  Capacity: Very large.
• Features of STM

  Coding: Acoustically

  Capacity: 7+-2 (Miller)

  Duration: 18-30 seconds.
• How is information passed back from LTM to STM?


  Retrieval
• How is information lost?

  Displacement - new information

  Decay - lost over time
• Features of LTM

  Coding: Semantically

  Capacity: Unlimited - some information may still be in LTM but not accessible.

  Duration: Potentially unlimited
• MSM

  
• Supporting evidence for capacity of STM


  Jacobs: Ps were read lists of words/numbers that they had to recalled immediately after the presentation. The length of the words or numbers was increased until Ps could only accurately recall the information, in the correct order, 50% of the time.

  Findings: Ps could recall 9 numbers but only 7 letters.

  Miller: We can remember 5 words and 5 letters by chunking/grouping sets of digits or letters into units. Suggested the capacity is 7+-2.
• Supporting evidence for duration of STM


  Peterson and Peterson: 24 university students were tested over 8 trials. On each trial, P was given a consonant syllable and a three-digit number. They were asked to recall the consonant syllable after a retention interval, during which they had to count backwards from their three-digit number.

  Findings: Ps were 90% correct after 3 seconds, 20% correct after 9 seconds, and 2% correct after 18 seconds
• Supporting evidence for coding of STM


  Baddeley: Ps heard words then had to recall them in the correct order.

  Findings: When they had to recall them immediately after hearing it they tended to do worse with acoustically similar words, suggesting STM is coded acoustically.
• Supporting evidence for coding of LTM


  Baddeley: Ps heard words then had to recall them in the correct order.

  Findings: When they had to recall them after an interval of 20 minutes, they tended to do worse with semantically similar words, suggesting LTM is coded semantically.
• Supporting evidence for duration of LTM


  Bahrick (1975): 392 participants aged 17-74 were tested for memory of old photographs and names of their school friends.

  Findings: Recall in matching names to faces was 90% after 15 years, and still 80% for names after 48 years. This suggests the duration of LTM is very large, potentially limitless.
• + Supporting evidence for MSM from case studies


  E - Clive Wearing and HM both suffered from amnesia. They both had severe damage to areas of their brains that contain the hippocampus. They both lost the ability to form new LTM, but had a normally functioning STM.

  E - This shows that STM and LTM are completely different stores.

  L - However, case studies cannot be generalised to everyone.
• / Conflicting evidence for MSM from case study


  E - Shallice and Warrington (1970) - K.F. lost his STM in a crash, but could still make new LTM.

  E - This shows that memories can be made without going through the process of STM to LTM with retrieval.

  L - Therefore, this contradicts the explanation of the MSM.
• / Studies into MSM often lack ecological validity


  E - Peterson and Peterson: experiment is unrealistic since learning lists of trigrams is not an ordinary activity.

  E - This means the research lacks ecological validity as it would be difficult to generalise to real-life settings.

  L - Therefore, research to support MSM typically lacks ecological validity.
• / Evidence from the WMM to show STM is more complex


  E - Baddeley and Hitch (1974) showed STM is more than just one simple unitary store and comprises of different components (e.g., central executive).

  E - This shows that the MSM is too simplistic and does not fully explain the process of memory.

  L - Therefore, the WMM is more accurate than the MSM.