coding capacity and duration of memory Flashcards
research on coding brief
info is stored in memory in different forms depending on type of memory store
process of converting info between different forms is called coding
Baddeley - gave different lists of words to four groups of participants to remember
what were the four groups that Baddeley set out
research on coding
group 1 - acoustically similar (sound the same)
group 2 - acoustically dissimilar (sound different)
group 3 - semantically similar (similar meanings)
group 4 - semantically dissimilar (different meanings)
results from the research on coding
participants were shown the original words and asked to recall them in the correct order
when done immediately recalling from STM they tended to do worse with acoustically similar words
when they recalled the word list after a time interval of 20 minutes recalling from LTM they did worse with the semantically similar words
findings suggest that info is coded in
acoustically - STM
semantically - LTM
give one strength about the coding research
separate memory stores
strength of Baddeley’s study is that it identified a clear difference between the two memory stores
later research showed that there are some exceptions to Baddeley’s findings
the idea that STM uses mostly acoustic coding and LTM mostly semantic has has stood the test of time
this was an important step in our understanding of the memory system
led to multistore model
give one limitation about the coding research
artificial stimuli
limitation of Baddeley’s study was that it used quite artificial stimuli rather than meaningful material
example - word lists had no personal meaning to participants
Baddeley’s findings may not tell us much about coding in different kinds of memory tasks especially in everyday life
when processing more meaningful data people may use semantic coding even for STM tasks
this suggests that the findings from this study have limited application
research on capacity - digit span
Jacobs - found out how much info STM can hold at on time by measuring digit span
example - researcher reads out 4 digits and participants recalls them in order
if correct the amount of digits would increase until the participant cannot recall the order correctly
indicates an individuals digit span
Jacobs found that the mean span for digits across all participants was 9.3 items
mean span for letters was 7.3
evaluation on digit span - research on capacity
a valid study
strength of Jacobs study is that it has been replicated
study is old and early research in psych often lacked adequate controls
example - some participants digit spans might have been underestimated because they were distracted during test (confounding variable)
despite this Jacobs findings have been confirmed by other better controlled studies since
suggests that Jacobs study is a valid test of digit span in STM
research on capacity - span of memory and chunking
miller - made observation’s of everyday practice
example - noted that things come in sevens
seven note son musical scale
seven days of the week
miller thought that the capacity of STM is about 7 items plus or minus 2
also noted that people can recall five words as easily as five letters
do this by chunking grouping sets of digits or letters into units or chunks
evaluation on span of memory and chunking - research on capacity
not so many chunks
limitation of millers research is that he may have overestimated STM capacity
Cowan - reviewed other research and concluded that the capacity of STM is only about 4 plus or minus 1 chunks
suggests that the lower end of millers estimate (five items) is more appropriate than 7
research on duration - duration of STM
margaret and peterson tested 24 students in 8 trials
on each trial the student was given a consonant syllable to remember
also given a 3 digit number
student counted backwards from this number until told to stop
counting backwards was to prevent any mental reversal of the consonant syllable which would increase the duration of the stm memory for the syllable
on each trial they were told to stop after varying periods of time 3 6 9 12 seconds (retention interval)
after 3 seconds average recall was about 80%
after 18 seconds 3%
peterson and petersons findings suggested that stm duration may be about 18 seconds unless we repeat the info over and over (verbal rehearsal)
research on duration - duration of LTM
bahrick studied 392 participants aged between 17 and 74
high school yearbooks were obtained from the participants or directly from some schools
recall was tested in different ways including
photo recognition
free recall
participants tested within 15 years of graduation were about 90% accurate in photo recognition
after 48 years recall was 79% for photo recognition
free recall was less accurate than recognition about 60% after 15 years
30% after 48 years
shows that LTM may last up to a lifetime for some material
evaluation on research on duration STM
meaningless stimuli in STM study
limitation of peterson and petersons study is that the stimulus material was artificial
study is not completely irrelevant because we do sometimes try to remover fairly meaningless material (phone numbers)
even so recalling consonant syllables do not reflect most everyday memory activities where want we are trying to remember us meaningful
means study lacked external validity
evaluation of research on duration LTM
Hugh external validity
strength of bahricks et al study is that it has high external validity
because researchers investigated meaningful memories (peoples names and faces)
when studies in LTM were conducted with meaningless pictures to be remembered recall rates were lower (shepard)
suggests that Bharick et als findings reflect a more ‘real’ estimate of the duration of LTM
