LTM recall - recall after a break - semantically similar/ dissimilar
What were the conclusions of Baddeley's research?
STM coding = acoustic
LTM coding = semantic
Evaluation of Baddeley's study:
Lab experiment - reliable, reproduceable, control over extraneous variables (e.g. same words, same time to recall/learn)
Lacks ecological validity - in a lab setting - not real life setting (e.g. could have been done in a classroom) - shows demand characteristics
Lacks construct validity - lists of random words rather than real life scenarios e.g. shopping lists
Describe Miller's Research?
observed everyday practice - noticed things come in 7s
e.g. musical notes, days of week, 7 sins
Therefore believed span of STM was 7 items +/- 2 (capacity)
Evaluate Miller's research?
Lack of research
overestimated capacity of STM
Nelson Cavan reviewed other research and concluded capacity is 4 +/- 1 chunks - towards the lower end of Miller's estimate
5 items is more appropriate
Describe Jacobs' Research?
Research into how much information can be held in the STM at one time
Read out 4 digits and increased the number every time until participants could not longer repeat it back to him
He concluded that the final number they could recall correctly was their digit span
On average 9.3 numbers and 7.3 letters immediately after being shown them
Evaluate Jacobs' Research?
Strength = it has been replicated
HOWEVER - it is a very old study and early research often lacked controls e.g. some participants digit spans may have been underestimated if they were distracted during the test - confounding variables.
BUT the findings were confirmed by better controlled studies (Bopp and Verhaeghen) who carried out a valid test of digit span in the STM
Describe Peterson and Peterson's study?
tested 24 undergrad students
8 trials - in each trial given a consonant syllable to remember and a 3 digit number to count backwards from until told to stop.
Each trial was stopped at a different time (e.g. 3,6,9,12,18 seconds
Suggested STM had a short duration.
Evaluate Peterson and Peterson's study?
Meaningless stimuli in STM study
The stimulus material was artificial although not completely irrelevant as we do sometimes have to remember fairly meaningless material (e.g. phone numbers)
Even so, recalling consonant syllables does not reflect most everyday memory tasks - lacks external validity
Describe Bahrick's research?
Aim was to study the duration of the LTM
Studied 392 American participants aged 17-74
He obtained their high school year books and tested their recall of the people present in various ways
photo recognition (50 photos)
free recall - names
He tested them after 15 years - photo recognition = 90%
tested them after 48 years - 70% photo recall
Free recall less accurate: 60% after 15 years and 30% after 48 years
Shows that LTM may last a lifetime
Evaluation of Bahrick's study: 1. Sample size was small 2. Sample was not representative of the population
High external validity - researchers investigated meaningful memories
When LTM studies conducted on meaningless pictures - recall rates lower
Gives a more 'real' estimate of the duration of the LTM
Whose research refutes Miller's?
Nelson Cavan
Whose research confirmed Jocobs'?
Bopp and Verhaeghen
How many trials did Peterson and Peterson do?
8
How many participants did Bahrick have?
392 Americans 17-74
What was the recall % after 15 years?
photos - 90%
free recall - 60%
What was the recall % after 48 years?
photo - 70%
free recall - 30%
Who developed the Multi-store Model?
Atkinson and Shiffrin
What did Atkinson and Shiffrin say?
Memory is a process. The information we learn passes through a number of stores during the journey from STM to LTM
Research on coding: information is stored in memory in different forms, depending on the memory store. The process of converting information between different forms is called coding