What is coding?
The format in which information is stored, in various memory stores
What is capacity?
The amount of information that can be held in a memory store
What is duration?
The length of time information can be held in memory
What is short-term memory?
The limited capacity memory store. In STM, coding is mainly acoustic, capacity is between 5-9 items, and duration is about 18 seconds
What is long term memory?
The permanent memory store. In LTM, coding is mainly semantic, it has unlimited capacity and can store memories for up to a lifetime
Who researched coding?
- Baddley
Who researched capacity?
- Jacobs
- Miller
Who researched duration?
- Peterson and Peterson
- Bahrick et al
What did Baddeley’s research into coding entail and what were the findings?
- Gave lists of words to 4 groups:
1: acoustically similar
2: acoustically dissimilar
3: semantically similar
4: semantically dissimilar - Participants given words to recall in the correct order
- When asked immediately (STM)- acoustically similar was worst
- When asked after 20 mins (LTM)- semantically similar was worst
- Info coded acoustically in STM and semantically in LTM
What did Jacobs research into capacity entail and what were the findings?
- Measured digit span
- Researcher reads 4 digits aloud and participant recalls in correct order aloud
- If correct, researcher reads 5 digits, then 6 and so on
- Found mean span for digits across participants= 9.3 items
- Mean span for letters= 7.3
What did Miller’s research into capacity entail and what were the findings?
- Made observations of everyday practice
- Noted all things come in 7s (days of week, deadly sins, etc)
- Miller thought span of STM is 7 (+ or - 2)
- Recall letters and words by chunking
What did Peterson and Peterson’s research entail and what were the findings?
- 24 students in 8 trials each
- On each trial, participant given a consonant syllable to remember
- Also given a 3 digit number
- Counted backwards from number until told to stop
- On each trial, they were told to stop after varying periods of time
- After 3 seconds, average recall= 80%, after 18 seconds, recall= 3% (STM)
What did Bahrick et al’s research entail and what were the findings?
- 392 American participants between 17 and 74
- Recall 1: photo recognition from high school yearbooks (50 photos)
- Recall 2: Free recall test, where participants recalled names of their graduating class
- Within 15 years of graduation= 90% accurate in photo recall and 60% in free recall
- After 48 years= 70% photo recognition and 30% free recall
- Suggests LTM can last a lifetime
What is the main strength of coding research?
I= identified a clear difference between two memory stores
D= STM uses acoustic coding and LTM uses semantic coding
E= led to development of multi-store model
What is the main limitation of coding research?
I= use of artificial stimuli rather than meaningful material
D= word lists had no personal meaning to participants, so findings tell us little about coding in everyday life. When processing more meaningful info, semantic coding is used even for STM
E= Suggests findings have limited application
What is the main strength of capacity research?
I= findings have been replicated
D= Jacob’s study lacks adequate controls. E.g: digit spans underestimated due to distractions. But findings confirmed by other, better controlled studies (Bopp and Verhaeghen)
E= Provides external validity
What is the main limitation of capacity research?
I= overestimated capacity of STM
D= Cowan reviewed other research and concluded the capacity of STM is about 4 chunks (+ or - 1)
E= suggests lower end of Miller’s estimate is more accurate than 7
What is the main strength of duration research?
I= High external validity in Bahrick’s study
D= Investigation of meaningful memories (names and faces). When LTM studies were conducted with meaningless pictures, recall was lower
E= findings reflect a more accurate estimate of duration of LTM
What is the main limitation of duration research?
I= artificial stimuli in Peterson and Peterson’s study
D= Consonant syllables are meaningless and do not reflect everyday memory activities
E= lack of external validity
