The Multi-Store Model of Memory

Atkinson and Shiffrin 1968

• Capacity --> A measure of the amount that can be held in memory
• Duration --> A measure of how long a memory lasts before it is no longer available
• Encoding --> The way information is changed so that it can be stored in the memory system (visual, acoustic or semantic)
• Retrieval --> Process in which information in your memory can be recalled

• Buffer for information in the environment (senses)  
• Iconic Memory --> visual sensory memory
• Echoic Memory --> brief memory for sound

• Encoding - none
• Capacity - 4-7 items
• Duration - 0.5-2 seconds and then disappears 

Sperling 1960:
Aim: To investigate the capacity of iconic memory

Method: 3x4 grid of numbers which were flashed for 0.05 seconds. This was followed by a high, medium or low pitched tone to indicate which row was to be recalled

Results: On average, participants were able to recall 80% on cued row

Conclusion: P's did not know which row was going to be recalled beforehand but still managed to recall it well. This indicates that at one time, all information was held in the sensory memory but decayed rapidly

• When information is attended to
• We forget through displacement and decay
• Retrieval in sequence

• Encoding - most likely to be encoded acoustically 
• Capacity - 5-9 items (chunking can increase the amount of information stored)
• Duration - 20-30 seconds

Peterson and Peterson 1959:
Aim: To investigate the duration of STM and provide empirical evidence for the MSM

Method: Participants had to recall trigrams and to prevent rehearsal p's had to count backwards in 3's until they saw a red light disappear 

Results: The longer the interval delay, the less trigrams recalled. After 35- 80%, after 185- less than 10%

Conclusion: STM has limited duration when rehearsal is prevented. Different to LTM duration so supports the MSM

• Encoding - visual, acoustic and semantic- semantic thought to be the best
• Capacity - thought to be limitless
• Duration - from a few minutes to a lifetime

• We forget through interference and decay
• Retrieval- semantic and using prompts 

Bahrick et al 1975:
Aim: To investigate the duration of the LTM

Method: Participants between the ages of 17 (just left school) and 74 (out of school for almost 60 years) were given 2 tests. 
1. Free recall --> names of people from their class
2. Pick out photos of their classmates from a range of 50 photos- some of which not in their class

Results: 90% accuracy remembering names and faces 34 years after graduation but this declined after 48 years, particularly for faces

Conclusion: Although the duration of LTM is hard to test, it could be a lifetime for some items 

Murdock 1962:

Aim: To investigate free recall and its effect on memory and to provide evidence for the MSM of memory

Method: Participants asked to learn a list of words and recall in any order

Results: End of list --> recalled 1st
Beginning of list --> recalled quite well
Middle --> not recalled well

Conclusion: When asked to recall a list of words, we recall the first (LTM) and last (STM) sections well and the middle are discarded 

6 mark question, points to include:

• All memory comes from an environmental stimulus
• If information from the environment is not attended to = discarded, if attended to = STM, if information from STM is not rehearsed = decay and displacement, rehearsed = LTM 
• It has 3 memory stores:
  1. sensory, capacity = 4-7 items, duration = 0.5-2 seconds
  2. short term, capacity = 5-9 items, duration = 20-30 seconds
  3. long term, capacity = limitless, duration = a few minutes- forever
• ^^ Stores have varied capacities and durations
• The different types of encoding include:
  1. visually
  2. acoustically
  3. semantically 
• We encode information, store information and retrieve information
• Retrieval can be by sequence, semantically or using prompts 

Evidence:
-Clive Wearing supports MSM. In free recall experiments he had good recency effects but poor primacy effects. This means he had a normal STM but was unable to transfer information into the LTM which supports that there are different stores of memory.

Applications and Implications to Real Life:
-The theory would benefit students. It explains that in order to create LTM, we need to repeat information over and over again. So, this gives teachers revision strategies to use in the classroom.

Comparisons and Credibility:
-The MSM is explained as too simplistic. For example, information from the LTM influences what is regarded and relevant, paid attention to in sensory and meaningful chunking information in STM. So, it under-emphasises the interaction between the stores.

How Good is Research:
-Laboratory studies using free recall experiments provide empirical evidence for MSM. There is high control over variables so a clear cause and effect can be shown. Primacy and recency effects show performance on certain memory tasks- distinction between STM& LTM

Evidence:
-Clive Wearing also criticises the MSM for being too simplistic. He could still play the piano and remember his wife- some LTM. There appears to be more than 1 type of LTM. Critics argue that the model doesn't differentiate enough between procedural, semantic and declarative memories. 

Comparisons and Credibility:
-More rehearsal is too simple for the transfer of information from the STM to the LTM. It ignores factors such as effort and strategy participants may use while learning and it doesn't account for types of information. A better theory is levels of processing as it considers elaborative learning- information is processed according to meaningfulness unlike MSM which states it's the amount of times you rehearse it 

How Good is Research:
-Case studies are a weakness. It only tests one unique individual with brain damage. This means it's hard to generalise results to the general population. It does not explain how memory works for 'normals'