Coding, Capacity and Duration of Memory

Question 1

define short term memory STM:

Answer 1

• the limited capacity memory store
• coding is mainly acoustic (sounds)
  -capacity between 5-9 items on average
  -duration around 18 seconds

Question 2

define long term memory LTM:

Answer 2

-permanent memory store
-coding mainly semantic (meaning)
-has unlimited capacity and
-can store memories for up to a lifetime

Question 3

define coding:

Answer 3

-format in which information is stored in the various memory stores

• the process of converting info between different forms

Question 4

define capacity:

Answer 4

amount of information that can be held in a memory store

Question 5

define duration:

Answer 5

length of time information can be held in memory

Question 6

what did Alan Baddeley (1966a, b) do?

Answer 6

Baddeley gave different lists of words to four groups of participants to remember

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

Question 7

explain the types of word groups these were?

Answer 7

group 1 - acoustically SIMILAR - words sounding similar

group 2- acoustically DISSIMILAR- words that sounded different

group 3 - semantically SIMILAR- words with similar meanings

group 4- semantically DISSIMILAR- words with different meanings

Question 8

what was the findings of this study?

Answer 8

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 LTM, they did WORSE with the semantically similar words

Question 9

what do these findings suggest?

Answer 9

that info is coded acoustically in STM and semantically in LTM

Question 10

Separate Memory Stores STRENGTH:

Answer 10

Baddeley’s study identified a clear difference between 2 memory stores

Later research shows that there are some exceptions of Baddeley’s findings

BUT the idea that STM uses mostly acoustic coding and LTM mostly semantic has stood the test of time

Question 11

therefore what does this mean?

Answer 11

this was an important step to understand the memory system which led to the multi-store model

Question 12

what is a LIMITATION of Baddeley’s study?

Answer 12

-study used quite artificial stimuli , rather than meaningful material

-e.g. word list had no personal meaning to participants SO the findings may not tell us much about different memory tasks (especially in everyday life)

-when processing more meaningful information, people may use semantic coding even for STM tasks

Question 13

so what does this suggest?

Answer 13

the findings from this study have LIMITED APPLICATION

Question 14

what did Joseph Jacobs 1887 study?

Answer 14

Capacity- found he measuring the digit span, he found what capacity is

Question 15

explain the study?

Answer 15

• the researcher read out 4 digits , participant recalls out loud in correct order
• if correct, researcher reads out 5 digits and so on until participant cannot recall correct
• which indicates the digit span

Question 16

what did Jacobs find?

Answer 16

that the mean span of digits across all participants was 9.3

mean span of letters was 7.3

Question 17

what is a strength of Jacobs study?

Answer 17

it can be easily replicated

although some of the participants digits spans may have been underestimated because they were distracted (confounding variables),

Jacobs studies have been confirmed by other better controlled studies since - Bopp and Verhaegen

suggests that his study was a valid test of digit span in STM

Question 18

Span of memory chunking - George Miller 1956:

Answer 18

Miller made an observation on everyday practice

he noted that things come in 7s

he thought that the span (capacity) of STM was around 7 items

he noted that people can recall 5 words easily as they can recall 5 letters

• this is done by chunking, grouping sets of digits or letters into units or chunks

Question 19

LIMITATION Miller ?

Answer 19

Miller may have overestimated STM capacity

• Nelson Cowan 2001 reviewed other research and concluded that the capacity of the STM is only around 4 chunks

this suggests that the lower end of Miller’s estimates (5 items) is more appropriate than 7 times

Question 20

Duration of STM : Margaret and Lloyd Peterson 1959

Answer 20

tested 24 students in 8 trials (each trial = one test)

on each trial, student given a consonant syllable to remember and a three digit number

student counted back from this number until told to stop (stopped any mental rehearsal of the consonant syllable , increasing duration of the STM for the syllable)

on each trial they were told to stop after periods of 3,6,9,12,15,18 secs , retention interval

Question 21

what were the findings?

Answer 21

after 3 secs - average recalls was around 80% , after 18 seconds 3%, unless we repeat the information over

the findings suggest that the STM duration may be about 18 seconds unless we repeat the information over and over VERBAL REHEARSAL

Question 22

LIMITATION - the Peterson’s study?

Answer 22

Meaningless stimuli in STM study:

-the study is not fully irrelevant as sometimes we try an remember meaningless information

• but recalling consonant syllables does not reflect most everyday memory activities where we try and remember meaningful things

so study lacks external validity

Question 23

Harry Bahrick 1975 study? Duration of LTM

Answer 23

392 American participants aged between 17 and 74

high school yearbooks from participants + from schools

recall testing included photo recognition , free recall

Question 24

what was the findings?

Answer 24

participants tested within 15 years of graduating were 90% accurate in photo recognition

after 48 years, recall declined to around 70% for photo recognition

free recall less accurate than recognition -60% after 15 years and drops to 30% after 48 years

shows that LTM may last up to a lifetime for some material

Question 25

STRENGTH of Bahrick’s study?

Answer 25

study had high external validity

• because researchers investigated meaningful memories - people’s names and faces

-when research was studies on meaningless pictures to be remembered, recall rates were lower (Shepard 1967)

this suggests that Bahrick’s findings reflect a more ‘real’ estimate of the duration of LTM