Coding, Capacity And Duration Flashcards
Define Coding
The format in which information can be held in a memory store
Define Capacity
The amount of information that can be held in a memory store
Define Duration
The amount of time information can be held in a memory store
What is Short-Term Memory
The limited-capacity memory store
Coding is mainly acoustic
Capacity of 5-9 items
Duration of 18-30 seconds
What is Long-Term Memory
The permanent memory store
Coding is mainly semantic
Capacity is unlimited
Duration lasts a lifetime
Alan Baddeley (1966) - Research on Coding
Gave lists of different words to 4 groups of participants to remember
Group 1) acoustically similar (cat, can, cab)
Group 2) acoustically dissimilar (pit, few, cow)
Group 3) semantically similar (great, large, big)
Group 4) semantically dissimilar (good, huge, hot)
Participants were shown the original words and asked to recall them in the correct order
When they recalled immediately (STM) they tended to do worse with acoustically similar words
When they recalled after a time interval of 20 minutes (LTM) they did worse with semantically similar words
Suggests information is coded semantically in the LTM
Joseph Jacobs (1887) - Research on Capacity - Digit Span
Researcher gives a certain number digits and the participants is asked to recall them in the correct order
If this is correct the researcher will increase the number of digits until the participant can no longer recall correctly
Found-
Mean digit span = 9.3
Mean letter span = 7.3
George Miller (1956) - Research on Capacity - Span of Memory and Chunking
Made observations of everyday practice (e.g. noted things that came in 7s)
Suggests that the capacity of STM is about 7 (+ or - 2) items
Also found that people can recall 5 words as well as they can 5 letters by using chunking (grouping) them together
Margret Peterson and Lloyd Peterson (1959) - Research on Duration
Tested 24 undergraduate students
Each student took part in 8 trials
On each trial the student was given a trigram and a 3-digit number to remember
The student was then asked to count backwards from the 3-digit number until told to stop (preventing mental rehearsal of trigram)
On each trial they were told to stop after a different amount of time (3, 6, 9, 12, 15 or 18 seconds) - retention interval
Found that the longer the retention interval, the lower the % of correct responses
Suggests the STM may have a very short duration
Harry Bahrick (1975) - Research on Duration - Duration of LTM
Studied 392 participants from Ohio aged between 17 and 74
High school yearbooks were obtained from the participants or their schools
Recall was tested in various ways:
1) Photo-recognition test - consisting of 50 photos some from the participants yearbook
2) Free recall - where participants recalled all the names of their graduating class
Participants who were tested within 15 years of graduation were about 90% accurate in photo-recognition
After 48 years this declined to 70%
Free Recall was less good compared to photo recognition
After 15 years it was 60% accurate
After 48 years it declined to 30% accurate
Shows that LTM can last a very long time
Evaluation (WEAKNESS) - Baddeley
Used Artificial Stimuli
Word lists had no personal meaning
Makes generalising more difficult
Suggests finding have limited application
Evaluation (WEAKNESS) - Miller
May have overestimated the capacity of STM
Cowan (2001) - reviewed other research and concluded that the capacity of STM was only about 4 chunks
Suggests the lower end of Miller’s estimate (5 items) may be more appropriate that 7 items
Evaluation (WEAKNESS) - Peterson and Peterson
Artificial Stimuli
Does not reflect real-life memory activities
Lacks External Validity
Alternative explanation is that information had been displaced
STM has limited capacity and new information will push out what is currently there
This may ophave happened when participants were counting down
Evaluation (STRENGTH) - Bahrick
High External Validity
Real-life meaningful memories were used
However confounding variables were not controlled (participants may have rehearsed this memory over the years)
Evaluation (STRENGTH) - Baddeley
Identified a clear difference between two memory stores
Important in our understanding of our memory system which led to the multi-store model
