Coding, Capacity and Duration Flashcards
coding
the format in which information is stored in the various memory stores
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
Coding = converting info from one form to another
Baddeley’s (1966) list of words to 4 groups of P’s to remember:
G1- (acoustically similar): cat, cab, can
G2- (acoustically dissimilar): pit, few, cow
G3- (semantically similar): great, large, big
G4- (semantically dissimilar): good, huge, hot
procedure & results from coding research
P’s = shown the OG words and had to recall them in correct order. When they did STM recall, they did worse on acoustically similar words
If P’s = when they did LTM recall, they did worse on semantically similar words
Shows that information is coded SEMANTICALLY in LTM
research on CAPACITY
How much info can STM hold at any 1 time?
Jacobs (1887) measured DIGIT SPAN
procedure & results from capacity research
Jacobs gave 4 digits and P has to recall these in the CORRECT ORDER out loud. If correct, reads out 5 digits etc. until P cannot recall order correctly. < determines P’s digit span.
Jacobs found: mean span for DIGITS across all P’s = 9.3 items and mean span for LETTERS = 7.3
span of memory & chunking research
Miller (1956) - things come in sevens, eg: 7 notes on music scale, 7 days of week, 7 deadly sins…
Capacity of STM = circa 7 items (plus or minus 2)
ALSO: people can recall 5 words as well as 5 letters — done by CHUNKING (group sets of digits/letters into chunks
research on DURATION
Peterson&Peterson (1959) - defining feature of STM, how precisely short is it? Tested 24 undergraduate students. Each student did 8 trials.
procedure & results from duration (STM) research
A ‘trial’ = one test. On each trial - student given a CONSONANT SYLLABLE (‘trigram’) to remember AND a 3-digit number.
Student = asked to count BACKWARDS from 3-digit number until told to stop.
Counting backwards prevented any MENTAL REHEARSAL of CS (increasing memory of it)
On each trial - told to stop after diff amounts of TIME > 3, 6, 9, 12, 15 or 18 seconds = called RETENTION INTERVAL
Suggests = STM may have a very short duration unless we REPEAT something over and over again (verbal rehearsal)
procedure & results from duration (LTM) research
Bahrick et al. (1975) got 392 P’s from OHIO aged (17-74).
Got yearbooks. Recall tested in these ways: (1) PHOTO-RECOGNITION test of 50 photos, some from P’s high school YB; (2) FREE RECALL = P’s recalled all names of their graduating class
P’s who were tested within 15 years of grad were 90% accurate in photo-recognition.
After 48 years = recalled decreased to 70% for photo-recognition
FREE RECALL = worse than PHOTO RECOG
After 15 years: 60% acc. and 30% acc. after 48 years
SHOWS THAT: LTM = lasts VERY LONG TIME
Evaluation of BADDELEY’S study (negative)
Used ARTIFICIAL STIMULI rather than meaningful material. Word lists = had no personal meaning to P’s. So can’t generalise the findings to diff kinds of memory task. Eg: when processing more meaningful info - ppl use SEMANTIC coding even for STM tasks
Suggests: the findings from study have LIMITED APPLICATION
Evaluation of JACOBS’ study (negative)
TEMPORAL VALIDITY = LOW. Early research = lacked adequate control. Eg: some P’s = distracted while being tested so didn’t perform as well as they might. Results could be INVALID due to CONFOUNDING VARIABLES (that weren’t controlled)
Evaluation of Miller’s study (negative)
May have overestimated capacity of STM. Eg: Cowan (2001) reviewed other research and concluded that capacity of STM was circa 4 chunks.
Suggests: the lower end of Miller’s estimate (5 items) is more appropriate than 7 items
Evaluation of P&P’s study (negative)
Stimulus material = artificial. Memorising consonant syllables doesn’t reflect REAL LIFE MEMORY activities
LACKS EXTERNAL VALIDITY (but we do try and remember meaningless things like phone numbers - so not TOTALLY irrelevant)
