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Memory

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Martyna Kudrycka

on 2 February 2014

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Transcript of Memory

Holds information for anything from a few miliseconds (iconic) to about 2 to 3 seconds (echoic)
Because each of the stores is particular to to the sense throuch which the information has entered, they are described as being MODALITY SPECIFIC.
Memory
Introduction
Memory - the retention of learning an experience
It is the process by which we keep information about the events that have happened in the past.
There are three stages of memory;
- Encoding - information is taken in through our senses and changed to create a memory trace.
- Storage - information is kept so that it can be used again
- Retrieval - finding information we have encoded and stores and getting it out from the memory so it can be used
STUDIES
The Working Model of Memory - Baddeley and Hitch (1974)
Indicated that there is more than one component in the STM
They used a dual task technique to support this idea
They saw STM as a work space where different operations can be carried out on both old and new memories.
They concluded that two tasks can be carried out in the STM simultaneously as long as they are dealt with by different parts of the memory.
Multi-Store Model of Memory - Atkinson and Shiffrin (1968)
The model arose from the information processing approach where memory is characterised as a flow of information through a system.
It is divided into a set of stages.
Information passes through each stage in a fixed sequence.
The model proposes that there are three permanent structures in memory: SENSORY MEMORY, SHORT-TERM MEMORY (STM) and LONG-TERM MEMORY (LTM)
The structures differ in terms of capacity (how much information they can hold), Duration (how long the information can be stored) and encoding (the format in which the information is stored).
Sensory Memory
Short-Term Memory
Active memory system
Contains the information you are currently thinking about
A place for temporary storage of information received from sensory memory.
Encoding
Mainly acoustic
Capacity
7 +/- 2 items
Duration
Up to 30 seconds
Long-Term Memory
Information can potentially be stored there forever
If not used the information may decay
It can also be lost due to brain damage, retrieval failure or interference.
Encoding
Mainly semantic
Capacity
Unlimited
Duration
Unlimited
Encoding
Information may enter the memory through any of the senses
The stores for vision (iconic store) and sound (echoic store) have been the most studied
Duration
Iconic
Echoic
30 seconds
(half a minute)
Up to 2 seconds
Duration
STM - Peterson & Peterson
(1959)
Method:
Laboratory experiment
The Participants were given a set of nonsense trigrams (eg.CVC, BGA) and were asked to recall them accurately and in the correct order.
Between exposure and recall, the participants were given a number to count backwards from, for a set period of time.
Findings:
Recall declined steadily over time
- After 3 seconds, 80% of recall was correct
- After 6 seconds, Less than 50% of recall was correct
- After 18 seconds, less than 10% of recall was correct
Nonsense trigrams were used to eliminate the effect of meaningfulness but nonsense trigrams are not the typical information encountered in every day life.
THE EXPERIMENT LACKS ECOLOGICAL VALIDITY
THE EXPERIMENT HAS LOW INTERNAL VALIDITY
The numbers may have displaced the trigrams in the STM rather than it just being an interference task
LTM - Bahrick et al. (1975)
Method:
An opportunity sample of 392 American participants aged between 17 and 74, who had left high school up to 48 years earlier were tested for recall of class mates
The participants were tested in four ways:
- Free recall of the names of as many ex-classmates as possible
- A photo recognition test where participants were asked to identify their former classmates from a set of 50 photos.
- A name recognition test
- A name recognition and photograph matching test
Findings:
90% accuracy in face and name recognition even with the participants who had left High School 34 years before
80% accuracy in name recognition after 48 years
40% accuracy in face recognition after 48 years
60% accuracy in free recall after 15 years
30% accuracy in free recall after 30 years
Conclusion:
The study supports the idea that LTM can store certain types of information for a very long time. Free recall becomes more difficult over time, however recognition isn't affected.

THIS STUDY HAS HIGH ECOLOGICAL VALIDITY
The study used a naturally occurring form of information and therefore avoided the artificiality which is often a limitation of memory studies
THE CONCLUSIONS OF THIS STUDY CANNOT BE GENERALISED
Classmates may have a high emotional significance and there is usually a large likelihood of rehearsal.
Capacity
STM - Jacobs (1887)
Method:
The experimenter read out lists of either letters or digits (omitting w and 7 as they have two syllables)
Participants were asked to recall the list in the correct order.
The length of the lists was gradually increased until the recall was accurate on only 50% of occasions.
Findings:
Jacobs found that the capacity for numbers was 9, while the capacity of letters was only 7
He also found that recall increased with age. On average, 8 year olds were only able to recall 7 digits while 19 year olds were able to recall 9 digits.
Conclusions:
The STM has a capacity between 5 and 9 items.
As our age increases we seem to develop better strategies for recall.
A study carried out by Miller in 1956 supports the findings and conclusions. He coined the phrase "The magic number seven, plus or minus two" to describe the capacity of the STM
THE STUDY LACKS ECOLOGICAL VALIDITY
The task used in this study is not one you're likely to come across in everyday life therefore we cannot apply these findings to real life
Encoding
STM & LTM - Baddeley (1966)
Method:
Lab experiment
Participants wear asked to learn on of four word lists:
-Acoustically similar (hair, chair, bear)
-Acoustically dissimilar
-Semantically similar (stool, chair, seat)
-Semantically dissimilar
The lists were recalled either immediately, to test STM, or after a timed delay to test LTM
Findings:
When recalling from STM, participants made more
acoustic
errors
When recalling from LTM, more
semantic
errors were made
Conclusions:
Encoding in the STM is mainly acoustic, while in the LTM it is mainly semantic
The results of this study make cognitive sense
For example if you were asked to remember a shopping list for a shot period of time you would probably repeat it aloud as you walk to the supermarket.
STM is not restricted to acoustic coding
The small difference between semantically similar (64%) and dissimilar (71%) lists suggests that, at best, there is minimal semantic coding in STM. We can also store visual images in STM and that would be extremely difficult to encode acoustically. you
Iconic Store (Sensory Memory) - Haber and Haber (1964)
Method:
Showed Children with a photographic memory, a picture of the cheshire cat for 30 seconds.
They were then given a blank card to look at.
Their recall was tested.
Findings:
The children were able to recall how many rings the cats tail had
As they were answering, their eyes skimmed the blank card as if they were still looking at the picture
Conclusions:
The capacity for detailed representation of a picture in the iconic store is half a minute
Echoic store (sensory memory) - Treisman (1964)
Method:
Participants heard a message played in each ear
They were asked to listen and repeat the message from one ear
The messages were identical but one was slightly delayed
Findings:
The participants only noticed that the messages were the same when the interval between them was 2 seconds or less
Conclusions:
The capacity of correct identification lasted for a maximum duration of 2 seconds for items in the echoic store
He presented his participants and asked them to recall as many as they can. He found that there is a difference in recall and he called this the serial position effect.
SUPPORTED BY MURDOCK (1962)
SUPPORTED BY THE CASE STUDY OF CLIVE WEARING
Clive Wearing was a musician. A brain infection destroyed his hippocampus along with some other parts of the brain. His STM was relatively unaffected however his LTM was impaired. He was incapable of transferring memories into the LTM. This supports the idea of different memory stores
THE MSM OVERSIMPLIFIES THE STORES
The Working Model of Memory shows that the STM is made up of at least 3 separate components: The central excutive; the phonological loop; and the visuo-spatial scratch pad.As for the LTM, Clive Wearing's case suggests that the LTM isn't a single store as he can remember how to do things such as playing the piano but he has lost his semantic and episodic memory.
Central Executive
This is a limited capacity, supervisory component
Has control over a range of processes:
-Setting task goals
-Monitoring and correcting errors
-Starting the rehearsal process
-Switching attention between tasks
-Retrieving from LTM
-Coordinating the activity needed to carry out more than one processing task at once
Supported by two slave systems which can be used as storage systems which frees up some of its own capacity
The slave systems work independently of one another.
Phonological Loop
Inner voice (articulatory control system)
Inner ear (phonological store)
Limited by recording length
Articulatory control system
Words can be maintained here by subvocal repetition
Limited capacity therefore it is a temporary storage system
This part of the store is responsible for speech production
VOCAL
Phonological Store
Limited capacity so it is a temporary store for holding verbal information in speech based form
Concerned with speech perception
Visuospatial sketchpad
Inner eye
Specialised in visual and/or spatial coding
A kind of writing pad for visual data
Limited capacity, temporary memory system
Evidence for central Exectutive
Activity in the central executive should increase when tasks are performed simultaneously
Bunge et al used fMRI to see which parts of the brain were more active when participants read a sentence and recalled the final word in each sentence (dual task)
The same areas were active for single or dual tasks but there was significantly more activation in the dual task condition
This suggests that increased additional demands were reflected in brain activity.
Evidence for articulatory process
The word-length effect disappears if an articulatory suppression task is used (eg. saying 'the the the...') while reading words
This repetitive task ties up the AL so you cannot rehearse the shorter words more quickly
Evidence for Visuo-spatial sketchpad
Baddeley gave participants a visual tracking task (tracking a moving light with a pointer)
At the same time they either described all the angles on the letter F or performed a verbal task.
Describing the angles was difficult while the verbal task was not. Presumably this was because it involved two different slave systems
Episodic Buffer
Baddeley found that when participants were shown words and then asked to immediately recall them , their performance was much better for sntences than unrelated words
This supports the idea of an immediate memory store for items that are neither phonological nor visual and that draws on LTM (to link the related words in a sentence)
SUPPORTED BY CASE STUDY OF KF
KF's short-term forgetting of auditory information was greater than that of visual stimuli. His auditory problems were limited in respect of verbal material such as letters and digits but not of meaningful sounds. Therefore his brain damage seemed to be restricted to the phonological loop.
EXTREMELY INFLUENTIAL AND USED BY MOST PSYCHOLOGISTS IN PREFERENCE TO MSM
MUCH MORE PLAUSIBLE THAN MSM AS IT EXPLAINS STM IN TERMS OF BOTH TEMPORARY STORAGE AND ACTIVE PROCESSING
CAN ACCOUNT FOR FINDINGS WHICH ARE DIFFICULT FOR MSM TO EXPLAIN
WHAT EXACTLY IS THE CENTRAL EXECUTIVE?
The answer appears to be that it allocates resources and is essentially the same as 'attention'. some psychologists argue that this is too vague
SOME BELIEVE THAT THE IDEA OF A SINGLE CENTAL EXECUTIVE IS WRONG AND THAT THERE ARE PROBABLY SEVERAL COMPONENTS
THE EVIDENCE COMES FROM CASE STUDIES OF BRAIN DAMAGED INDIVIDUALS THEREFORE YOU CANNOT MAKE BEFORE AND AFTER COMPARISONS, SO YOU CANNOT BE SURE WHETHER THE CHANGE OF BEHAVIOUR IS CAUSED BY THE DAMAGE.
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