coding, capacity and duration of memory Flashcards
who did research on coding
Baddeley
when did Baddeley do research on coding
-1996a
-1996b
what is coding
the format in which information is stored in the various memory stores
what were the 4 groups in Baddeley’s study on coding
-group 1, acoustically similar
-group 2, acoustically dissimilar
-group 3, semantically similar
-group 4, semantically dissimilar
what were participants asked to do in Baddeley’s study
shown words a list of words and asked to recall them in order
baddeleys’s study results
-when asked to recall immediately (short-term memory), they did worse on acoustically similar words
-when asked to recall the word list after 20 mins (long-term memory) they did worse on semantically similar words
Baddeley’s conclusion
information is coded acoustically in STM and semantically in LTM
who did research on digit span
Jacobs
when did Jacobs do research on digit span
1887
how is an individuals digit span measured
researcher reads out number of digits (eg 4) and participants recall out loud in correct order. this occurs until the participant cannot accurately recall the digits
what did Jacobs find mean digit span to be
9.3 items
what did Jacobs find mean span for letters to be
7.3 items
who did research on span of memory and chunking
Miller
when did Miller do research on span of memory and chunking
1956
what did Miller’s research involve
observations of everyday life, he noted that things come in 7s such as days of the week, and musical scales and deadly sins
Miller’s results
-capacity of STM is 7 plus/minus 2
-people can recall 5 words as easily as they can recall 5 letters, this occurs by chunking
what did Miller describe chunking to be
grouping sets of digits or letters into units or chunks
who did research on duration of STM
Peterson and Peterson
when did Peterson and Peterson do research onto duration of STM
1959
procedure for Peterson and Peterson research on STM
-tested 24 students in 8 trials
-on each trial, the student was given a consonant syllable to remember
-they were also a given a 3 digit number
-the students has to count backwards from this number until told to stop (this was to prevent mental rehersal of the constant syllable which would increase duration of STM)
-on each trial, they were told to stop after varying periods of time 3,6,9,12,15,18 seconds
Peterson and Peterson research onto duration of STM results
-after 3 seconds average recall was 80%
-after 18 seconds average recall was about 3%
Peterson and Peterson conclusion
STM duration is around 18 seconds, unless we repeat the information over and over
who did study on duration of LTM
Bahrick et al
when did Bahrick et al research duration of LTM
1975
Bahrick at al sample
392 American participants aged 17-74
Peterson and Peterson sample
24 students
procedure for Bahrick et al’s study on duration of LTM
-392 American participants aged 17-74
-high school year books were obtained and recall was tested in various ways
-the first way of recall was the photo-recognition test consisting 50 photos, some from the participants high school year book
-the second way of recall was participants recalled name of their graduating class
Bahrick et als study on duration of LTM findings
-participants tested within 15 years of graduation were 90% accurate in photo recognition
-after 48 years, recall declined to about 70% for photo recognition
-free recall was less accurate then photo-recognition
-free recall was 60% for after 15 years
-free recall was 30% after 48 years
Bahrick et als study on duration of LTM findings on photo-recognition
-participants tested within 15 years of graduation were 90% accurate in photo recognition
-after 48 years, recall declined to about 70% for photo recognition
-more accurate then free recall
Bahrick et als study on duration of LTM findings on free recall
-free recall was less accurate then photo-recognition
-free recall was 60% for after 15 years
-free recall was 30% after 48 years
Bahrick et als study on duration of LTM conclusion
LTM may last up to a lifetime for some material
strength of Baddeley’s research on coding
-shows separate memory stores as the is a clear difference identified in the study between the two memory stores. later research has shown some exceptions to Baddeley’s findings but understanding that STM is coded acoustically and LTM is coded semantically is still used.
-this was an important step to our understanding of the memory system which lead to the multi-store model
limitation of Baddeley’s research on coding
-used artificial stimuli rather than meaningful material. this was because the word lists had no personal meaning to participants so may not tell us much about coding in different kinds of memory tasks, especially in everyday life.
- when processing meaningful information, people may use semantic coding even for STM tasks
-this suggests the findings have limited application
strengths of research on capacity
-Jacob’s study has been replicated, this study is very old so lacked adequate control. replication means that Jacob’s findings have been confirmed by other, more controlled studies such as Bopp and Verhaeghen (2005)
-this suggests that Jacobs’ study is valid test of digit span in STM
limitation of research on capacity
-Miller’s research may have overestimated STM capacity
-Cowan (2001) reviewed other research and concluded capacity of STM is 4 +- 1 chunk
-suggests that lower end of millers estimate is more appropriate than 7 items
strength of research on duration
-Bahrick’s study has high external validity due to researchers investigating meaningful memories. when studies on LTM were conducted on meaningless pictures to be remembered, recall rates were lower –> suggests that Bakrick et al’s findings were a more real estimate to duration of LTM
limitation of research on duration
-Peterson and Peterson’s study had an artificial stimulus material. althogh we do sometimes remember fairly meaningless material such as phone numbers, remembering constant syllables does not reflect most everyday memory activities when what we are trying to remember is meaningful –> lacked external validity
