Coding, Capacity and duration Flashcards
Process of coding
The format in which information is stored in various memory stores
Who investigated Coding?
Alan Baddeley (1966a, 1966b)
Alan Baddeley’s study into coding
Gave four different lists of words to four groups of participants:
- G1 - acoustically similar words (cat, cab, can)
-G2 - acoustically dissimilar words (pit, few, cow)
-G3 - semantically similar words (great, large, big)
-G4 - semantically dissimilar (good, huge, hot)
Participants showed words and asked to recall them immediately in the correct order (from short term memory)
Then asked to recall them after 20 minutes (from long term memory).
A mixture of 72 men and women used from Cambridge university, volunteered
Baddeley’s results
From short term memory, did worse with acoustically similar words, suggesting short term memory codes acoustically. As the STM pays not attention to what the words mean, but gets confused as they sound similar
From long term memory, did worse on with semantically similar words, suggesting long term memory is coded semantically
Baddeley - strengths
Strengths:
- Identified clear difference between stores
-Later research showed there are some exceptions to findings but the idea that STM codes semantically and LTM acoustically has remained
-Baddeley’s findings were important in development of multi-store model
Baddeley limitations
Limitations:
-Experiment used artificial stimuli rather than meaningful material, no personal meaning. May not tell about coding in different tasks in everyday life. When processing meaningful information, people may use semantic coding even for STM tasks
-Suggests investigation has limited application
Capacity of memory
The amount of information that can be held in a memory store
Research on capacity
Joseph Jacobs (1887) - digit span
Joseph Jacobs (1887) - procedure
-Researcher read out list of numbers for participants to recall in order
-If order was correct, list of numbers increases from 4 digits + until the participant is incorrect
-This indicates the individual’s digit span
Jospeh Jacobs’s - results
Found the mean span for digits across all participants was 9.3 items. Mean span for letters was 7.3
Jacob’s strengths
-Has been replicated various times
-Old studies can lack controls, e.g. (Digit span may have been underestimated as they were distracted when taking the test - confounding varibale)
-Jacob has been confirmed by controlled studies (Bopp and Vertaeghan 2005)
George Miller - 1956
Made observations of everyday items - lots come in groups of 7
Thought the span of STM was about 7, plus or minus 2
Claimed people can recall 5 words as easily as they can recall 5 letters. Do this by chunking
Miller’s limitation
Nelson Cowan (2001) - reviewed other research and found that STM is only about 4 (plus or minus 1) chunks
Said that the lower end (5 items) is more appropiate
Duration of STM
Margaret and Lloyd Peterson (1959) - tested 24 students in eight trials each
Given a 3 digit number, then told to count backwards until they were told too top (prevent mental rehearsal)
Told to stop after varying periods of time - 3, 6, 9, 12, 18 (retention interval)
Peterson and Peterson results
- After 3 seconds, average recall was about 80%
- After 18 seconds, average recall was about 3%
Peterson and Peterson’s findings suggested that STM duration may be about 18 seconds, unless we repeat the information over and over (verbal rehearsal)
Duration of LTM
Harry Bahrick et al (1975)
Bahrick - procedure
Studied 392 American participants between 17 and 74
High school yearbooks, and memory recall tested:
- Photo recognition test consisting of 50 phots, some from their year book
-Free recall test where participants recalled all the names from their graduating class
Bahrick - results
- Participants tested within 15 years of graduation were about 90% accurate in photo recognition
- After 48 years, recall declined to about 70% for photo recognition
- Free recall was less accurate than recognition - about 60% after 15 years, dropping to 30% after 48 years
This suggests that LTM may last up to a lifetime for some material
Bahrick strengths
-High internal validity - meaningful memories were investigated
-LTM studies on meaningless pictures had less accurate results (Shepard 1967)
-Suggesting Bahrick’s results give a more accurate result
Peterson limitation
-Stimulus was artificial
-Wasn’t completely irrelevant as we do need to remember some meaningless material but recalling 3 digit numbers does not reflect every day memory
-Lacked external validity
