Coding Capacity and Duration of Memory Flashcards
(18 cards)
Define coding
The format in which information is stored in various memory stores
Define capacity
The amount of information that can be held in a memory store
Define Duration
The length of time information can be held in memory
Short term memory (STM)
Definition,Coding capcity and duration
-The limited capacity memory store.
-Coding is mainly acoustic (sounds),
-Capacity is between 5-9 items
-Duration is between 18 and 30 seconds
Define Long Term Memory (LTM)
-Known as the permanent memory store.
-Coding is mainly semantic (meaning)
-It has unlimited capacity
-Stores memories for up to a lifetime
Procedure of Baddeleys research on coding
This study proves that information is coded semantically in LTM
- Baddeley (1966)-Gave different lists of words to four groups of participants to remember
- Ppts were then shown the original words and asked to recall them in the correct order
What were the 4 groups of particpants Alan Baddeley used
Group 1- Acoustically similar -words sound similar-
Group 2- Acoustically dissimilar
Group 3- Semantically similar -words with similar meanings-
Group 4- Semantically dissimilar
only one of those groups needs mentioning in a 16 marker
Findings of Alan Baddeley (1966) research on coding (5)
- STM was worse with acoustically similar words
- Suggesting that information is coded acoustically in STM
- If participants were asked to recall the words after a time interval of 20 mins (LTM recall), They did worse with the semantically similar words.
*This suggests information is coded semantically in LTM
Research on capacity- Digit span Procedure (3) and findings
- Joseph Jacobs (1887) developed a technique to measure digit span.
- The researcher gives for example, 4 digits and then the participant is asked to recall these in the correct order out loud.
- If this is correct the researcher reads out 5 digits and so on until the participant cannot recall the order correctly.
- The mean span for digits across all ppts was 9.3 items
- The mean span for letters was 7.3
Research on capacity- Span of memory and chunking- (4)
The guy obsessed with 7s
- George Miller (1956) made observations of everyday practice.
- For example he noted that things come in sevens: there are 7 notes on the musical scale, 7 days of the week, 7 deadly sins and so on.
- This suggests that the span (or capacity) of STM is about 7 items (plus or minus 2).
- Miller also noticed that people can recall 5 words as well as 5 letters and they do this by chunking-
Define chunking
When large pieces of information is divided into smaller chunks that are easier to retain in short-term memory
Research on Duration-Duration of STM (7)
Shows that the duration of STM is short
- Peterson & Peterson (1959) Tested 24 students.
- Each student took part in 8 trials. On each trial a student was given a trigram (such as YCG) to remember and was also given a 3 digit number.
- The student was then asked to count backwards from that 3 digit number until told to stop.
- The counting backwards was to prevent any mental rehearsal.
- On each trial they were told to stop after a different amount of time -3, 6, 9 seconds-
- Their findings suggest that STM may have a very short duration unless it is repeated over and over again
Research on Duration-Duration of LTM (6)
- Bahrick (1975) Studied 392 ppts aged 17-74.
- High school yearbooks were obtained from the ppts or directly from some schools.
- Recall was tested through photo-recognition tests which consisted of 50 photos from their high school yearbook and a free recall test where ppts recalled names of their graduating class
- Ppts 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.
- 60% after 15 years then 30% after 48 years for free recall
- This shows that LTM can last a very long time
Limitation to Baddeleys study (4)
Artifical stimuli
- One limitation of Baddeleys (1966) study was that is used artifical stimuli rather than meaningful material.
- The word lists had no personal meaning to ppts which means we should be cautious about generalising the findings to different kinds of memory tasks
- For example, when processing more meaningful information, people use semantic coding even for STM tasks
- This suggests that the findings from this study have limited application
One limitation of Joseph Jacobs (1887) Confouding variables (4)
- One limitation of Jacobs’s study is that it was conducted a long time ago and early research in psychology often lacked adequate control.
- For example, some participants may have been distracted while they were being tested so they didn’t perform as well as they might.
- This would mean that the results might not be valid because there were
confounding variables that were not controlled. - However, the results of this study have been confirmed in other
research, supporting its validity.
Limitation of George Miller (1956) (3)
(Overestimated)
- One limitation of Miller’s research is that he may have overestimated the capacity of STM.
- For example, Cowan (2001) reviewed other
research and concluded that the capacity of STM was only about four chunks. - This suggests that the lower end of Miller’s estimate (five items) is more appropriate than seven items.
Limitation of Peterson and Peterson (1959)
(3) (Artifical stimuli)
- A limitation of Peterson and Peterson’s study is that the stimulus material was artificial.
- Trying to memorise consonant syllables does not reflect most real-life memory activities where what we are trying to remember is meaningful. So we might say that this study lacked external validity.
- However, we do sometimes try to remember fairly meaningless
things, such as phone numbers, so the study is not totally irrelevant.
Limitation of Bahrick (1975) (3) (High External validity but may have confounding variables)
- One strength of Bahrick et al.’s study is that it has higher external validity.
- Real-life meaningful memories were studied. When studies on LTM have been conducted with meaningless pictures to be
remembered, recall rates were lower (e.g. Shepard 1967). - The downside of such real-life research is that confounding variables are not controlled, such as the fact that Bahrick’s
participants may have looked at their yearbook photos and rehearsed their memory over the years.
