Coding, capacity and duration of memory

Question 1

Explain the research on coding

Answer 1

Info is stored in memory in diff forms, depending on the memory store. The process of converting info between diff forms is called coding.
Alan Baddeley (1966a,1966b) gave diff lists of words to 4 groups of participants to remember.
- 1 acoustically similar- words that sounded similar
-2 acoustically dissimilar- words sounding different
- 3 semantically similar - words with similar meanings
4 semantically dissimilar - words with diff meanings

Question 2

explain the findings of research into coding. Mentions what these findings suggest

Answer 2

participants were shown the original words and asked to recall them in the correct order. When they did this task 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 mins, recalling from LTM, they did worse with the semantically similar words. these findings suggest that info is coded acoustically in STM and semantically in LTM.

Question 3

explain the research on capacity

Answer 3

Joseph Jacob’s (1887) found out by measuring digit span. E.G the researcher reads out 4 digits and the participant recalls these out loud in the correct order. If this is correct the research increases the number of digits read outloud until the participant cannot recall them correctly. this indicated the individuals digit span.
Jacob’s found that the mean spam for digits across all participants was 9.3 items. the mean span for letters was 7.3.
Span of memory and chunking: George Miller (1956) made observations of everyday practice. he noted that things come in 7’s. miller thought that the spam (i.e capacity) of STM is about 7 items, plus or minus 2. but he also noted that people can recall 5 words as easily as they can recall 5 letters. we do this by chunking and grouping letters into smaller sections

Question 4

what are the two sections in research on capacity

Answer 4

digit span
- Jacobs (1887). Researcher read out 4 digits and the participant recalls these out loud in the correct order. If its correct researcher then reads out 5 digits and so on… until participant cannot recall them correctly which indicated an individuals digit span
- found the mean across all participants was 9.3 items and mean for letter was 7.3.

Span of memory and chunking
-George Miller (1956) made observations of everyday practice like he noticed things come in 7’s. Miller thoughts that the span (capacity) of STM is about 7 items plus or minus 2.
- he also noticed people can recall 5 words as easy as 5 letters- we do this by chunking- grouping sets of digits/numbers together.

Question 5

Explain the research on duration of both short term memory and long term memory

Answer 5

short term memory
- Margaret and Lloyd Peterson (1959) tested 24 students in 8 trials
- one trial was given a consonant syllable and a 3-digit number. Student counted backwards from this number and then told to stop (to prevent mental rehearsal).
- on each trial they were told to stop after varying periods of time: 3,6,9,1,15,18 seconds (retention interval)
- findings: after 3 secs average recall was about 80%, after 18 it was 3% so the findings suggest that STM duration may be about 18 seconds

Duration of LTM
- Bahrick et al. (1975) studies 792 American participants between ages 17 and 74.
- recall was tested by (1) photo-recognition test consisting of 50 photos from participants high school year books (2) free recall where participants recalled all the najmes of their graduating class.
- those tested within 15 years of graduation were about 90% accurate in photo recognition. After 48 years, recall reclined to about 70%. Free recall was less accurate than recognition- about 60% after 15 years dropping to 30% after 48 years so LTM may last up to a lifetime in some material

Question 6

evaluate the research on coding

Answer 6

separate memory stores (strength)
- identifies a clear difference
- the idea that STM uses mostly acoustic and LTM mostly semantic has stood the test of time. Important in understanding on memory system - multi store model.

Artificial stimuli (limitation)
- Baddeley’s study used quite artificial stimuli rather than meaningful material to participants.
- therefore doesn’t tell us about coding in everyday life
- limited application

Question 7

evaluate research on capacity

Answer 7

a valid study (strength)
- Jacobs study has been replicated
- findings have been confirmed by other controlled studies e.g Bopp and Verhaeghen 2005.

Not so many chunks (limitation)
- Miller’s research may have overestimated STM capacity
- Cowan (2001) reviwed other research and concluded that the capicity of STM is only about 4 plus or minus 1 chunks.
so lower end of Millers estimations is more appropriate to use.

Question 8

Evaluate research on duration

Answer 8

meaningless stimuli in STM study (limitation)
- material was artificial in Peterson and Petersons study
- does not reflect everyday activities
- so lacked external validity.

High external validity (strength)
- Bahrick et al’s. study.
- because researchers investigated meaningful material like memories when studies on LTM were conducted with meaningless things recall rates were lower (Shepard 1967)
so Bahricks findings reflect a more real estimate of the duration of LTM