memory: coding, capacity and duration Flashcards
define coding
the way in which info is stired in your memory
state 3 examples of coding
acoustic: based on sound
visual: based on images
semantic: based on meaning
outline Baddeley’s study on the coding of STM and LTM
Baddeley gave four different lists of words to four groups of participants to remember.
* Group 1 (acoustically similar): words sounded similar (Cat, Cab, Can)
* Group 2 (acoustically dissimilar): words sounded different (Pit, Few, Cow)
* Group 3 (semantically similar): words with similar meaning (Great, Large, Big)
* Group 4 (semantically dissimilar): words that all had different meanings (Good, Huge, Hot)
Participants recalled the words immediately and after 20 minutes.
outline the results of his study
He found participants had difficulty remembering acoustically similar words in STM. Participants also found it hard to remember semantically similar words in LTM.
* This suggests that STM is encoded acoustically whereas LTM is encoded semantically.
* It also supports the idea that STM and LTM are separate stores
AO3: Baddeley > didn’t test LTM
One weakness of Baddeley research on coding is that he may not have tested LTM. In this study, Baddeley tested STM by asking participants to recall a word immediately after hearing
it. LTM was tested by waiting 20 minutes.
WEAKNESS: as it can be suggested that this is not really LTM, so the study does not represent an accurate picture of the coding of LTM.
AO3: Baddeley > artificial stimuli
One weakness of Baddeley research on coding is that he used artificial stimuli > He used stimuli such as: Cat, Cab and Can. The lists had no personal meaning to the participants.
WEAKNESS as the study lacks external validity, and the findings cannot be used to explain memory in real life. As we do not memorise lists of meaningless words. So we cannot apply Baddeley’s ideas of how STM and LTM is coding to real life examples of memory
we should be cautious about generalising the findings to different kinds of memory tasks. For example, when processing more meaningful information, people may use semantic coding even for STM tasks.
This suggests that the findings from the study have limited application.
define capacity
the amount of information that can be held ina memory store
outline Jacobs digit span test
Jacobs proposed the digit-span task. 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 participants cannot recall the order correctly. This determines the individuals digit- span.
Jacobs used the digit span task. He found that the average span for digits was 9.3 items and 7.3 for
letters. Jacob suggests it is easier to remember digits
what is the capacity of STM
Jacobs concluded that STM has a capacity of 5-9 items (7+/-2)
outline chunking
Miller notes that people can recall 5 words as well as they can recall 5 letters. They do this by chunking
* Chunking: grouping sets of digits or letters into chunks
AO3: capacity of STM > individual differences
research on capacity does not take into account individual differences
Research suggests that the capacity of STM is not the same for everyone. For example, Jacobs found that recall increased steadily with age. 8 year olds could remember an average of 6.6 digits whereas the mean for 19 years olds was 8.6 digits
This may be because as age increases there may be a gradual increase in brain capacity, and/or it may be that people develop strategies to improve their digit span as they get older such as chunking.
WEAKNESS as findings of the capacity of STM are not representative of the entire population, as people may have a different capacity due to factors such as age.
AO3: capacity of STM > overstated
One weakness is that the research on the capacity of STM may have been overstated.
Miller suggests that the capacity of STM is 7 items (plus or minus two). Additionally, he suggests we can remember 5 chunks just as well as 5 words.
However, Cowan conducted a review on the capacity of STM and concluded that STM is limited to about four chunks. Similarly, Vogel et al found that the capacity of STM for visual information was about four items. This means that the lower end of Millers range is more appropriate (7-2 =5).
WEAKNESS as his findings are not completely accurate
outline Peterson and Peterson’s study of duration of STM
tested 24 undergraduate students.
* Each participant took part in 8 trials.
* On each trial, the student was given a consonant syllable (also known as trigram), such as YCG to remember. They were also given a 3 digit number.
* They were told to recall the consonant syllable after a retention interval of 3, 6, 9, 12, 15 or 18 seconds.
* During the retention interval, they had to count backwards from the 3 digit number until told to stop.
* The % of trigrams correctly recalled was recorded for each time interval.
outline results on the study of duration of STM
90% were correct over 3 seconds,
20% correct after 9 seconds,
2% correct after 18 seconds.
what is the duration of STM
STM has a short duration of 18 -30 seconds, if rehearsal is prevented.
AO3: duration of STM > low ecological validity
the study lacks ecological validity, as they used meaningless stimuli.
They gave each participant a consonant syllable, such as YGF to recall. This is an artificial stimuli. This does not reflect real life memory activities, where what we are trying to remember is meaningful. This suggests the study lacks external validity. So the study is not representative and therefore we cannot use the findings to explain real life examples of memory.
COUNTER: However, it can be suggested that we occasionally try to remember meaningless things, such as phone numbers. So the study is representative of certain situations.
AO3: duration of STM > not measuring STM
it was not measuring the duration of STM
In the study, participants were counting numbers in their STM and this may displace or overwrite the constant syllable to be remembered. Additionally, Reitman repeated the study, however he used auditory tones instead of numbers so that displacement wouldn’t occur (sounds don’t interfere with verbal rehearsal). Reitman found the duration of STM was longer.
WEAKNESS as this suggests that forgetting in the Peterson and Peterson’s study was due to displacement rather than decay and was not measuring the duration of STM.
outline Bahrick et al’s study on duration of LTM
Bahrick et al studied 400 participants from America, aged between (17-74)
* High school year books were obtained from the participants
* Recall was tested in various ways: 1. photo-recognition test consisting of 50 photos 2. free recall test where participants recalled all the names of their graduating class
* For photo recognition, participants who were tested within 15 years of graduation were about 90% correct. After 48 years, recall declined to about 70%.
* For free recall, after 15 years after 60% accurate. After 48 years, 30% were accurate.
AO3: duration of LTM > external validity
it is high in external validity
This is because Bahrick investigated meaningful memories such as the names and faces of people. When research into the duration of LTM uses meaningless pictures, recall rates are lower.
This suggests that Bahrick’s findings reflect a more real estimate of the duration of LTM and can be applied to memory in real life
