Coding, Capacity, Duration Flashcards
What is coding? Coding for STM and LTM?
The format in which information is stored.
STM - Acoustic, LTM - Semantic
What is duration Duration for STM and LTM?
The length of time for which information can be stored.
STM - 18 seconds, LTM - Lifetime
What is capacity. Capacity of STM and LTM
The amount of information a memory store can hold.
STM - 5-9, LTM - Unlimited
Name and outline the study which investigated the capacity of STM
Jacobs 1887
Read out 4 digits to participants who had to recall them out loud in the correct order. If recalled correctly, the researcher reads out 5 digits and so on until the participants cannot recall the order correctly - this is the individuals digit span.
Mean span for digits is 9.3 and for letters its 7.3
Name and outline the procedure which investigated the duration of STM
Peterson and Peterson (1959) Participants were given nonsense trigrams (e.g. ZFB) · Had to count backwards in threes from a large three-digit number (to prevent mental rehearsal) for varying periods of times ·
Correct recall of trigrams after 3 seconds= 80% · Correct recall of trigrams after 18 seconds= 3% · Suggests STM duration= about 18 seconds
Name and outline the study which investigated the duration of LTM
Bahrick et al. (1979) 400 participants aged between 17 and 74 years were shown a set of photos and names (some random and some from old yearbooks) and were asked to identify ex-school friends.
Those who’s left high school in last 15 years identified 90% of faces and names. Those who’d left 48 years previously identified 80% of names and 70% of faces · Suggest that memory for faces is long lasting
Name and outline the study which investigated the coding of STM and LTM
Baddeley 1966. Gave different lists of words to 4 groups of participants to remember:
Group 1 – words sounded similar (e.g. cat, cab, can)
Group 2 – words sounded different (e.g. pit, few, cow)
Group 3 – words with similar meanings (great, large, big)
Group 4 – words with different meanings (e.g. good, huge, hot) Participants were shown original words and asked to recall them in correct order ·
When recalled immediately (recall from STM), they did worse with acoustically similar words. Info with similar sounds conflicted with each other.
When recalling list after 20 minutes (recall from LTM), they did worse with semantically similar words. Words with similar meanings conflicted with each other.
Suggest that information is coded acoustically in STM and semantically in LTM/
Strength and limitation of research on capacity
Consistent over time. Jacobs finding have been replicated and confirmed by other better controlled studies. Valid test of digit span.
Overestimated capacity. Cowan 2001 reviewed other STM capacity research and concluded that capacity of STM is only 4 +-1
Strength and limitation on research on coding
Consistent evidence. Baddeley’s finding that STM is coded acoustically and LTM semantically has stood the test of time. Distinguishing between the 2 types of memory was an important step in our understanding of memory that led to the MSM.
Artificial materials. Not meaningful to participant and doesn’t reflect most everyday memory activities. It may not tell us much about coding in different memory tasks in everyday life. When processing more meaningful information people may use semantic coding for STM tasks. Limited application.
Strength and Limitation (with counter) for research on duration
Bahrick et al 1975 has high external validity as researchers investigated meaningful memories (names and faces)Reflect a more “real” estimate of the duration of LTM.
Artificial stimuli. Peter and Peterson used artificial nonsense syllables which doesn’t reflect everyday memory activities where we are trying to remember meaningful info. Lacks external validity.
