What does the Multi-store model of memory propose?
Three singular stores of memory
- Sensory register (holds immediate sensory information)
- Short term memory (holds information we are paying attention to in active, readily available state)
- Long term memory (holds memories for potentially lifetime)
What is coding, capacity and duration for each store?
- Sensory register: coded in modality specific way (depends on sense), capacity is very large, lasts approx 250ms
- Short term memory: coded acoustically, capacity is 7 +/- 2 items, lasts for 18-30 seconds
- Long term memory: coded semantically (by meaning), capacity is potentially unlimited, lasts potentially a lifetime
Describe how information passes through the stores in a linear way
- Sensory stimuli enter the sensory register
- If paid attention to, enters short term memory
- Rehearsal loop maintains STMs
- Through maintenance rehearsal (continuous repetition), may transfer to LTM
- Retrieval from LTM to STM occurs when recalling from LTM
Outline research into coding of STM and LTM
- Baddeley presented participants with random list of words
- Words were either acoustically similar and dissimilar, or semantically similar and dissimilar
- Participants asked to write words down 20 seconds after presentation (test STM) or 20 minutes after presentation (test LTM
- When testing STM, confused words in acoustically similar category more than other categories
- When testing LTM, confused words in semantically similar category more than others
- Concluded that STM coded acoustically and LTM coded semantically
Outline research into capacity of STM
- Researcher provided participants with a series of digits
- Instructed to immediately recall in correct order
- As test continued, list of digits became longer (another digit added)
- Participants could remember up to 9, average was 7 and lower boundary was 5
- STM has capacity of 7 +/- 2 items, however can be increased by chunking items together
Outline research into capacity of LTM
- Researcher tested his recall of thousands of events (precisely 2400) that he had written in a diary over a number of years
- Found he had excellent recall of these events
- LTM has very large capacity
Outline research into duration of STM
-Researchers provided participants with consonant trigrams (three consonant letters e.g. JKD, MFN)
- Rehearsal prevented, asked them to count backwards in threes from specified number
- After intervals of 3,6,9,12,15 and 18 seconds, participants asked to stop counting and to repeat trigrams
- % of trigrams correctly recalled was recorded each interval
- Found after 3 seconds, participants could recall about 80%
- After 18 seconds, only about 10% of trigrams recalled correctly
- STM last approximately 18-30 seconds before decay
- Can be extended through rehearsal loop
Outline research into duration of LTM
- Researchers showed photos to graduates from high school
- Either given names to match to photos or simply named them without cues
- Participants who graduated more recently were better at both matching photo and recalling with no cues
- Those tested many years after were still able to match photos to names and freely recall some of names
- LTM can potentially last a lifetime
- May be lost over time due to natural decay of memories or retrieval failure due to absence of cues
Outline research into coding of sensory register
- Researcher presented participants with different types of sensory information (included visual and auditory information)
- Could remember visual information for few milliseconds, could remember auditory for slightly longer
- Coded in modality specific way (duration lasts longer depending on sense)
Outline research into capacity and duration of sensory register
- Researcher tested in two tasks
- Participants briefly presented with 3x4 grid containing 12 letters, asked to recall letters they could remember
- Participants briefly presented with 3x4 grid containing 12 letters, participants asked to recall specific row of 4 letters depending on tone they hear (high tone is top row, medium tone is middle row, low tone is bottom row)
- In task 1 found on average they recalled 4-5 letters out of 12
- In task 2 found on average they recalled 3 out of 4 letters on row indicated
- Task 2 proves capacity of sensory register is very large
- Task 1 proves duration of sensory register is approximately 250ms (very small)
Outline one strength of research into coding, capacity and duration of sensory, STM and LTM
- Highly controlled
- Standardized procedures employed in controlled laboratory settings while manipulating independent variable
- E.g. Baddeley used standardized procedures (same number of words to be recalled) while manipulating whether words were acoustically similar/dissimilar or semantically similar/dissimilar
- Strength because high level of control enabled cause and effect to be established (acoustically similar words leading to poorer recall of STM)
- Adds validity
Outline one limitation of research into coding, capacity and duration of sensory, STM and LTM
- Most of research is artificial
- E.g most tasks required participants to recall random digits, letters, list of words
- limitation because such tasks fail to reflect how sensory, STM and LTM are used in everyday life
- Questions mundane realism of findings from this research
Outline final limitation of research into coding, capacity and duration of sensory, STM and LTM
- Risk of researcher bias
- E.g Waagenar’s research into capacity of LTM involved him testing himself on memories he’d written in his diary over a number of years
- Limitation because Waagenar may have been subjective in judging accuracy of his own recall about his own personal events (no one can cross check)
- Therefore questions validity of these findings
Outline one strength of the multi-store model of memory
- Research evidence to support ideas of distinct memory stores
- E.g Baddeley found participants confused words in STM that sound similar while confusing words in LTM that have similar meanings
- Difficulty recalling words in STM with similar sounds suggests it is coded acoustically
- Difficulty recalling words in LTM that have similar meanings suggests it is coded semantically
- Strength of MSM because supports they are different memory stores since coded differently
- Therefore adds validity
Outline one limitation of the multi-store model of memory
- Oversimplified process of transferring STMs to LTMs
- Proposes more STM rehearsed, more likely to transfer to LTM
- Limitation because researchers argue what really matters is type of rehearsal
- Maintenance rehearsal (simply repeating) proposed to maintain STMs whereas elaborative rehearsal (thinking about meaning of information on deeper level) is needed for long term storage
- Explains why students who read notes many times before exam struggle to remember information
- Questions validity
Outline final limitation of the multi-store model of memory
- Linear view of memory has been questioned
- Patient KF showed impaired STM but intact LTM
- Limitation of MSM because although findings support claim that STM and LTM are separate stores, MSM proposes information has to pass through STM to reach LTM
- Means damage to KF’s STM should have impaired ability to transfer STM’s to LTMs
- Not the case so questions validity of MSM as linear model of memory
