Coding,capacity and duration Flashcards
What is coding ?
The format in which information is stored in the memory stores
STM- Acoustic
LTM - semantic
What is Capacity ?
The amount of information that can be held in a memory store.
STM-5-9 Items
LTM-Unlimited capacity
What is duration ?
The length of time information can be held in the memory
STM - 18-30 Sec
LTM-Lifetime
Researcher for coding ?
Alan Baddeley
Researcher for Capacity ?
Joseph Jacobs (1887)
George Miller
Researcher for duration ?
Margaret and Llyod Peterson (1959)
Bahrick and colleagues (1975)
Research on coding ? Procedure
Coding - process of converting information from one form to another.
Baddeley gave different lists of words to 4 groups of ppts to remember ;
1) acoustically similar - words sounded similar ( cat cab can)
2)acoustically dissimilar - words sounded different (pit,few)
3)Semantically similar - words with similar meanings (great large big)
4)semantically dissimilar (words with different meanings (good,huge)
Ppt’s were shown the original words and asked to recall them in the correct order. When they had to do this recall tasks
Research on coding ? Findings
STM RECALL - When they had to do this recall tasks immediately after hearing ; they tended to do worse with acoustically similar words
LTM RECALL - ppt asked to recall after a 20 min interval , they did worse with semantically similar words.
Suggesting ;
STM-acoustic
LTM - semantic
Research on capacity ? Digit Span
Digit Span : Jacobs (1887) developed a technique to measure digit span. Eg. 4 digits are given and then the ppt is asked to recall these in the correct order out loud. If this is correct , ppt reads out 5 digits and so on until they cannot be repeated.
- Determines individual digit span
-Jacobs found the mean span for all ppt was 9.3 ITEMS
-7.3 mean span for letters
Research on Capacity ? Span of memory and Chunking
George miller made observations of everyday practise
-Noted things come in sevens
-Eg.Days if week,deadly sins
This suggests span of STM is 7 items +/- 2
Chunking -Grouping sets of digits or letters into units or chunks
Miller noted people can recall 5 words and 5 letters done by chunking
Research on duration ? STM
Peterson and Peterson tested 24 undergrad students.
Each student took part in 8 trials.
1 trial = 1 test
Each trial the student was given a constant syllable known as a trigram (Eg. YCG ) - to remember and also given a 3 digit number.
Student was told to count backwards from the 3 digit number until told to stop. (counting backwards was to prevent any mental rehearsal of the trigram).
After each trial they were told to stop after different amounts of time (3,6,9,12,15 or 18 sec) - Retention interval.
Findings - GRAPH - STM - may have a very short duration unless we repeat something over and over again
Research on duration ? LTM
Bahrick and his colleagues (1975) studied 392 ppt from the American state of Ohio aged 17-74
High school yearbooks were obtained from the ppt or directly from some schools.
Recall was tested by ; 1.photo recognition test of 50 photos , some from high school yearbook.
2.Free recall test , ppts recalled names of their graduating class
Findings of LTM duration research :
Ppt who were tested within 15 years of graduation were about 90% accurate in photo recognition.
After 48 years, recall declined to about 70% for photo recognition
Free recall was less good ; after 15 years this was 60% accurate and 30% after 48 years
LTM - can last a very long time.
