coding capacity and duration MEM Flashcards
short term memory STM
the limited capacity memory store, coding is mainly acoustic, capacity is between 5 & 9 items, duration is 8 seconds
long term memory LTM
permanent memory store, coding is mainly semantic, unlimited capacity and can store memories for a lifetime
coding
the format in which information is stored in the various memory stores
The process of converting information between different forms
capacity
the amount of information that can be held in a memory store
duration
the length of time information can be held in memory
research on coding
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Baddeley gave different lists of words to 4 groups of participants
Acoustically similar
Acoustically dissimilar
semantically similar
Semantically dissimilar
Participants were asked to recall words in the correct order immediately and then another group after 20 minutes. Recall from STM was WORSE with acoustically similar words and recall from LTM was WORSE with semantically similar words.
→ information is coded acoustically
digit span
Jacobs 1887 found out about the capacity of the STM by measuring digit span.
* Mean span for digits was 9.3 items
* Mean span for letters was 7.3
memory and chuncking
Miller 1956 made observations of everyday practices eg things come in sevens:
* Days of the week
* Deadly sins
* Etc
He thought that the span of STM was 7 + or - 2. But he also found out that people can recall 5 words as easily as 5 letters by chunking.
duration of STM
Peterson and peterson tested 24 students in 8 trials
Constant syllables on each trial to remember
3 digit number to count back from (reduces mental rehearsal of syllable)
Told to stop after varying periods of time
After 3 seconds → recall was 80%
After 18 seconds → recall was 3%
duration of LTM
**Bahrick et al **1975
studied 392 American participants
between the ages of 17 and 74
Yearbooks were used to test photo-recognition and free recall
Within 15 years of graduation → 90% accurate in photo-recognition, 60% free recall
After 48 years → 70% accurate in photo recognition, 30% free recall
LTM may last up to a lifetime for some material
coding
separate memory stores
strenght
Baddeley
Clear difference
STM uses mostly acoustic and LTM uses mostly semantic has not been disproven
Important to understand memory system and lead to multistore model
coding
artificial stimuli
limitation
Baddeley
No personal meaning
Doesn’t tell us much about coding
Limited application
capacity
a valid study
strength
Replicated
Conformed by other studies (Bopp and Verhaeghen)
Valid test of digit span in STM
capacity
not so many chunks
limitation
Overestimated STM capacity
Cowan
STM is only 4 + or - 1 chunks
Lower end of Millers estimate is more appropriate
duration
high external validity
strength
Bahrick
Investigated meaningful memories
Reflects a more ‘real’ estimate of the duration of LTM
