Please enable JavaScript.
Coggle requires JavaScript to display documents.
The Multi Store Model - Short Term Memory - Coggle Diagram
The Multi Store Model - Short Term Memory
STM temporarily stores information received from the SR . It is an active (changing) memory system as it contains information currently being thought about
STM differs from LTM especially in terms of coding , capacity and duration and how information is forgotten. There are several explanation for forgetting STM
Coding in STM
Information arrives from the SR in its original raw form , such as in sound or vision and is then encoded in a form of STM can more easily deal with
For example if the input from the SR was the word platypus this could be coded into STM in several ways
Visually - thinking of an image of a platypus
Acoustically - repeatedly saying the word platypus
Semantically - by using a knowledge of platypuses
Research suggests that the main form of coding in STM is acoustic but other codes exist too
Influence of acoustic and semantic similarities on short and long term memory for word sequences - Alan Baddeley (1966)
Aim
To assess whether coding in STM and LTM is mainly acoustic or semantic
Procedure
75 participants , four lists
List A - Acoustically similar words ( eg cat , mat , sat )
List B - Acoustically dissimilar words ( eg pit , day , cow )
List C - Semantically similar words ( eg big , tall , huge )
List D - Semantically dissimilar words ( eg hot , safe , foul )
To test coding in STM participants were given a list containing the original words in the wrong order . Their task was to rearrange the words in the correct order
To test coding in LTM , the procedure was the same but with a 20 minute interval before recall , where participants performed another task to prevent rehearsal
Findings
For STM , participants given list A performed the worst , with a recall of only 10% . The confused similar sounding words . Recall for the other lists was comparatively good at between 60 and 80 %
For LTM , participants with list C performed the worst , with a recall of only 55% . They confused similar meaning words . Recall for the other lists was comparatively good at between 70 and 85 %
Conclusions
For STM , since list A was recalled the least efficiently , it seems theres acoustic confusion in STM , suggesting STM is coded on an acoustic basis
For LTM since list C was recalled the least efficiently , it seems theres semantic confusion in LTM , suggesting LTM is coded on a semantic basis
Evaluation
Baddeley's findings make cognitive sense . Eg if you had to remember a shopping list , you'd probably repeat it aloud ( acoustic rehearsal ) while walking to the shops , but if you had to recall a book you've read , you remember the plot , rather than every single word
The small difference in recall between semantically similar (64%) and semantically dissimilar (71%) lists , suggests theres also semantic coding in STM
Laboratory study and therefore shows causality but may lack ecological validity
Can be replicated as it is a laboratory study
Research for coding in STM
Posner and Keele ( 1967 ) found participants were faster in assessing that 'A' followed by an 'A' is the same letter than when 'A' was followed by an 'a' , the findings show that visual coding was occurring , which illustrates how codes other than the acoustic one occur in STM
Coding in STM evaluation
Although research shows that coding in STM is mainly acoustic , other sensory codes such as visual are used too . Some stimuli like faces or the smell of food would be difficult to code acoustically . For example what would the sound of treacle be ?
Capacity of STM
STM has a limited capacity , as only a small amount of information is held in this store .Research indicates between 5 and 9 items can be held , though capacity is increased by chunking , where the size of the units of information in storage is increased by giving them a collective meaning
Jacobs (1887) tested STM capacity with the serial digit span method , where participants are presented with increasingly long lists of numbers or letters and have to recall them in the right order . When participants fail on 50% of tasks , they are judged to have reached their capacity . He found that capacity for numbers was 9 and letters was 7 . Numbers may be easier to recall as there are only 9 single digit numbers compared to 26 letters in thee english alphabet . Although this study lacked mundane realism
Miller (1956) reviewed research to find the capacity of STM compared to be between 5 and 9 items but that the 'chunk' was the basic unit of STM . This means 5 to 9 chunks can be held at any one time , increasing the stores capacity . Although Simon (1974) found that this varies depending on the type of material being recalled and how much is in each chunk
Capacity in STM evaluation
Other factors , like age and practice , also influence STM capacity and nowadays STM limitations are mostly seen as due to processing limitations associated with attention
There may be individual differences in STM capacity , Daneman and Carpenter (1980) found capacity varied between five and twenty items between those with advanced and poor reading comprehension
Duration of STM
The amount of time information remains within the STM without being lost is limited to a maximum of about 30 seconds
This can be extended by rehearsal of the information which if done enough will result in transfer of the information into LTM , where it will become a more long lasting feature
Marsh (1997) found that is participants weren't expecting to have to recall information , STM duration was only between two and four seconds , which suggests duration of STM is affected by thee amount of time taken to process information
Peterson and Peterson (1959) read nonsense trigrams to participants and then got them to count backwards in threes from a large digit number ( to prevent repetition ) for varying period of time . They found that 90% of trigrams were recalled correctly after 3 seconds but only only 5% after 18 seconds , which suggests that STM duration is between 20 and 30 seconds . However the results may be flawed due to methodology because different trigrams were used on each trial , this may have led to interference between items , leading to decreased recall . Also , recalling nonsense trigrams has little relevance to STM tasks in everyday life
Duration of STM evaluation
Reitman (1974) suggested the brief duration of STM is due to displacement , as new information comes into the STM it pushes out existing information due to its limited capacity
There is little in the way of research evidence considering the STM duration of other forms of stimuli , like visual images
