Memory Flashcards
Memory
It is the process by which we retain information about events that have happened in the past
Coding
The format that information is stored in the memory stores
Capacity
This is a measure of how much can be held in the memory
Duration
The length of time information can be held in memory
Coding:
Baddeley (1966)
Procedure
Group 1 - acoustically similar (cat,cab,can)
Group 2 - acoustically dissimilar (pit,few,cow)
Group 3 - semantically similar (great,large,big)
Group 4 - semantically dissimilar (good,small,hot)
Pts shown original words and asked to recall them in correct order
Coding:
Baddeley (1966)
Findings
- when recalled immediately after (STM), did worse in acoustically similar
-when recalled 20 minute after (LTM), did worse with semantically similar
these support that information is coded acoustically in STM and semantically in LTM
Coding:
Baddeley (1966)
Evaluation
- artificial stimuli rather than meaningful, difficult to generalise, limited application
+identified clear difference between two memory stores.
Capacity of STM
Between 5-9 items
Capacity for LTM
Unlimited
Research on capacity:
1. Digit span technique (Jacob’s, 1887)
- pts given 4 digits and have to recall them aloud in right order
- if correct given 5 digits, had to recall them aloud
- continued until pt can’t recall in correct order
-determines individuals digit span
Found: mean digit span was 9.3 and mean span for letters was 7.3
Research on capacity:
2. Span for memory and chunking (Miller, 1956)
Miller suggested capacity of stm is 7 plus or minus 2.
People can recall words as well as letters
Chunking:
Grouping sets of digits or letters into units or chunks
Evaluation of capacity
-lacking validity, Jacob’s study: conducted long time ago, lack of control, pts distracted. - result not as valid as there were confounding variables
- not so many chunks, Millers study: overestimated capacity of stm, Cowan found capacity of stm was 4 chunks
Duration of STM
Limited duration of 30 seconds
Duration of LTM
Unlimited, last whole life
Duration of LTM
Unlimited, last whole life
Research on duration of STM
Peterson and Peterson (1959)
Aim:
To see if rehearsal is needed to keep information in the STM
Research on duration of STM
Peterson and Peterson (1959)
Procedure:
Tested 24 undergraduates who took part in 8 trials
Each student given consonant syllable(YGM) to remember and a 3 digit number.
The pt had to count backwards from from 3 digit number until told to stop (3,6,9,12,15,28 seconds)
Pts had to recall consonant syllables
Research on duration of STM
Peterson and Peterson (1959)
Findings:
Performance was worse when pt had to count backwards for 18 seconds
Conclusion: STM has very short duration, unless rehearsal is used
Research on duration of STM
Peterson and Peterson (1959)
Findings:
Performance was worse when pt had to count backwards for 18 seconds
Evaluation of duration of STM
- limitation to Peterson and Peterson: stimulus material was artificial, doesn’t reflect real life. Lack external validity
- pts in Peterson and Peterson is counted down during retention interval therefore may be other reasons as to why pts may have struggled. STM may be displaced
Duration of LTM
Bahrick et al (1975)
Aim:
Investigate the duration of LTM, wanted to show memory could last several decades/life
Duration of LTM
Bahrick et al (1975)
Procedure:
Pts included 392 American ex-high school students age 17-74
Recall was tested:
1. Free recall of the names or as many of their former classmates as possible
2. Photo recognition test where they were asked to identify former classmates in a set of 50 photos
3. Name recognition test
4. A name and photo matching test
Duration of LTM
Bahrick et al (1975)
Findings
Pts who tested within 15 years of graduation were 90% accurate.
After 45 years declined to 80% for name recognition and 70% for photo recognition
Duration of LTM
Bahrick et al (1975)
Conclusion
Shows information can be retained for a LTM for a very long time
Duration of LTM
Bahrick et al (1975)
Evaluation
+high external validity as real life meaningful memories were studied.
- confounding variables not controlled e.g pts may have looked at their yearbook photos and rehearsed their memory over the years
Overview of STM
Coding: acoustically
Capacity: 5-9 items
Duration: 30 secs
Overview of LTM
Coding: semantically
Capacity: unlimited
Duration: unlimited
Multi-store model of memory
Who proposed it?
Atkinson shiffrin (1968)
Multi store model of memory
Sensory register:
Iconic memory: visual (images)
Echoic memory: (audio)
Maternal in sensory register lasts briefly
Duration: less than half a second
Capacity: high capacity.
Multi store model of memory
Maintenance rehearsal:
Course when we repeat material to ourselves over and over again. The information will remain in our STM as long as we rehearse it
If rehearsed long enough, pass to long term memory.
Evaluation of MSM
+supporting research evidence: Baddeley research agreed
-more than one type of STM: study of KF: suffered from brain damage , worse at recalling when told them,but shown digits better at recalling.
- more than one type of rehearsal :maintenance rehearsal, elaborating rehearsal
Supporting evidence for STM/LTM
Murdock (1962)
Procedure: Murdock asked pts to learn list for words that varied in length from 10-40 words. Each word presented for 1 to 2 seconds
Results:probability of recalling depended on positioning in the list, early or end in list. Position effect
Conclusion:words early in list put into LM because person had rehearsed each word acoustically.
