Memory: Duration, Capacity And Coding Flashcards
What is memory
The process by which we retain information about events that have happened in the past
What is short term memory ?
Memory for events in the present of immediate past
What is long term memory
Memory for events that have happened in the more distant past
Define duration ?
The length of time information can be held in memory
What is the duration of the stm ?
The short term memory store has limited duration
Memories will disappear unless they are rehearsed
What will rehearsal eventually lead to ?
Short term memories will become long term
What method did Peterson and Peterson (1959) use for their stm study ?
24 university students
Experimenter said consonant syllable followed by 3 digit number
Participants had to count back from number in 3s or 4s until told to stop
- this was to stop participant rehearsing syllable -> rehearsal would aid recall
Participants asked to recall the nonsense syllable
Two practice trails then 8 trials
Each trial retention interval was different: 3,6,9,12,15 or 18 seconds
What where the results and conclusion of Petersons and Peterson’s (1959) study
3 second interval - 80% of the syllables were recalled correctly and 2% when there was 18second interval
When rehearsal is prevented, STM duration lasts about 20 seconds
What is the duration of the LTM ?
Last from 2 minutes to 100 years
Unlimited duration
What was the method of bahrick et al 1975 study ?
392 participants
American state of ohio - aged 17-74
High school yearbooks obtained from participants or directly from schools
Recall was tested in various ways
1)photo recognition of 50 photos some from yearbooks
2)free recall where participants recalled all the names of their graduating class
What were the rings and conclusion of bahrick et als research
Participants who were tested within 15 years were about 90% accurate
After 48 years recall reclined to about 70% for photo recognition
Free recall was less good than recognition
After 15 years- 60% accurate
After 48 years - 40% accurate
LTM can last a very long time
What is a limitation of Peterson’s and Peterson’s study (artificial)
A limitation of p+p study is that the stimulus material was artificial.
Memorising consonant syllables does not reflect real life memory activities
Where
What we remember is meaningful
This shows that results cant be generalised to real life experiences and that the study lacks external validity
What is a strength of bahrick et ls research
It has higher external validity Used real life meaningful memories For example Studies into LTM with meaningless pictures had lower recall rates Shepard 1967 Can be generalised to real life
Increases risk confounding variables as participants may still see their classmates today or may have looked at their yearbook over the years and rehearsed
What is capacity
The amount of information that can be held in memory store
What is the capacity for stm and LTM
Mean span for digits - 9.3 items
Mean span for letters - 7.3
How is the stm capacity assessed explain
Joseph jacobs 1887 study
Using digit span
Researcher for example gives 4 digits then the
participant is asked to recall these in correct order
If this is correct then researcher reads out 5 digits
This continuous on until participant can’t recall order correctly.
Explain George millers study on span of memory (1956)
Made observation of everyday practice.
Found that many things come in 7s eg 7 notes on musical scale, 7 days of the week
He concluded that the span of stm is 7 +or- 2 items
In addition he concluded peoples recall 5 letters as well as they can recall 5 digits
This is due to chunking
Grouping sets of data into units or chunks
What is coding
The format in which information is stored in various memory stores
How is the stm coded and how is the LTM coded
Stm coded acoustically
(Information represented in sounds)
LTM coded semantically
(Information is represented by its meaning )
Explain the procedure of baddeley 1966 research
4 different conditions
Each condition had slightly different list of words
Group a - acoustically similar
Group b - acoustically dissimilar
Group c - acoustically similar
Group d - acoustically dissimilar
Participants shown the word and asked to recall in correct order
What were the results of baddeleys study
Immediately after (stm) recall, tended to do worse with acoustically similar words Stm coded acoustically
Recall words after 20 minutes (LTM recall) they did worse with semantically similar words
LTM coded semantically
What is a limitation of baddeleys study
Used artificial stimuli
Rather than meaningful material
As the words had no personal meanings to the partcipants
It could be possible that when processing meaningful info we may use semantic coding for STM
Findings - limited application
Problems with generalisability
What is a limitation of jacobs study (effects of time)
Study was conducted a long time ago
Early research lacks control
Some participants distracted while being tested
Confounding variables like this not controlled
Lacked internal validity
Results have been confirmed by other studies - increasing validity
