~RESEARCH ON CODING~

• The process of converting information between stores is called coding

ALAN BADDELEY gave different lists of words to 4 groups of pps to remember:

• Group 1 (acoustically similar): words sounded similar (e.g. cat, can, cab)

• Group 2 (acoustically dissimilar): words sounded different (e.g. pit, few, cow)

• Group 3 (semantically similar): words with similar meaning (e.g. great, large, big)

• Group 4 (semantically dissimilar); words with different meanings (e.g. good, huge, hot)

Pps were shown the original words and asked to recall them in the correct order

• When they did this task immediately, recalling from short-term memory (STM), they tended to do worse with acoustically similar words

• After 20 mins, recalling from long-term memory (LTM), they did worse with the semantically similar words

• These findings suggest that information is coded acoustically in STM and semantically in LTM

EVALUATION

+ SEPARATE MEMORY STORES (CODING)

• One strength of Baddeley‘s study is that it identified a clear difference between two memory stores.

• Later research showed that there are some exceptions to Baddeley’s findings.

• But the idea that STM uses mostly acoustic coding, and LTM mostly semantic has stood the test of time.

• This was an important step in our understanding of the memory system, which led to the multi-store model.

- ARTIFICIAL STIMULI (CODING)

• One limitation of Baddeley‘s study was that it used quite artificial stimuli rather than meaningful material.

• For example, the words lists had no personal meaning to participants.

• So the findings may not tell us much about coding in different kinds of memory tasks, especially in everyday life. When processing more meaningful information, 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 read out four digits and the pps recalls these out loud in the correct order

• If this is correct, the researcher reads out five digits, and so on until the pps cannot recall the order correctly

• This indicates the individual’s digit span

• The findings show that the mean span for digits across all pps was 9.3 items. The mean span for letters was 7.3

Span Of Memory And Chunking

• MILLER thought that the span of STM is about 7 items, plus or minus 2 (due to everything coming in 7’s (e.g. 7 days of the week, 7 deadly sins etc))

• He also noted that people can recall 5 words as easily as they can recall 5 letters, by chunking (grouping sets of digits or letters into units or chunks)

EVALUATION

+ A VALID STUDY (DIGIT SPAN)

• One strength of Jacob‘s study is that it has been replicated.

• The original study is very old, and early research in psychology lacked adequate controls. For example, some participants‘ digit spans may have been underestimated if they were distracted by confounding variables during testing.

• Despite this, the findings have been confirmed by other, better controlled studies since.

• This suggests that Jacob‘s study is a valid test of digit span in STM.

- NOT SO MANY CHUNKS (SPAN OF MEMORY & CHUNKING)

• One limitation of Miller‘s research is that he may have overestimated STM capacity.

• A psychologist reviewed other research and concluded that the capacity of STM is only about 4 chunks.

• This suggests that the lower end of Miller‘s estimate (5 items) is more appropriate than seven items.

RESEARCH ON DURATION

Duration Of STM

• PETERSON & PETERSON tested 24 students in 8 trials each

• In each trial, the student was given a consonant syllable (such as YCG) to remember. They were also given a 3-digit number

• Students counted backwards from this number until told to stop (this was to prevent any mental rehearsal of the consonant syllable, which would increase the duration of STM memory for the syllable)

• In each trial they were told to stop after varying periods of time: 3, 6, 9, 12, 15, or 18 seconds (the retention interval)

• After 3 seconds, average recall was 80%, and after 18 seconds it was 3%

• These findings suggest that STM duration may be about 18 seconds, unless we repeat the information over and over (verbal rehearsal)

Duration Of LTM

• BAHRICK ET AL studied 392 American pps aged between 17-74

• Using their high school yearbooks, recall was tested using (1) photo recognition test consisting of 50 photos, some from the yearbooks, (2) free recall test where pps recalled all the names of their graduating class

• Pps tested within 15 years of graduation were about 90% accurate in photo recognition. After 48 years, recall declined to 70%

• Free recall was less accurate than recognition - about 60% after 15 years, dropping to 30% after 48 years

• These findings show that LTM may last up to a lifetime for some material

EVALUATION

- MEANINGLESS STIMULUS IN STM STUDY (STM DURATION)

• One limitation of Peterson & Peterson‘s study is that the stimulus material was artificial.

• The study is not completely irrelevant because we do sometimes try to remember fairly meaningless material.

• However, recalling consonant syllables does not reflect most everyday memory activities.

• From this, we can question how applicable it is to real-life scenarios, which leads to a lack in external validity.

+ HIGH EXTERNAL VALIDITY (LTM DURATION)

• One strength of Bahrick et al‘s study is that it has high external validity.

• This is because the researchers investigated meaningful memories (i.e. people’s names and faces).

• When studies on LTM were conducted with meaningless pictures to be remembered, recall rates were lower.

• This suggests that Bahrick et al‘s findings reflect a more ‘real’ estimate of the duration of LTM.