Models of Memory
Memory is part of cognitive psychology.
Types of Memory
Atkinson & Schiffrin (1968) created the multi-store model of memory. It’s based on the assumption there are three kinds of memory:
Short term memory (STM)
Long term memory (LTM)
Storage for unprocessed information for fractions of a second after a physical stimulus is no longer available. It’s assumed we have separate sensory stores for all the different senses but it’s the visual sensory store (iconic memory) which has attracted the most research.
Short term memory
Holds information for brief periods of time. ( Baddely and Hitch renamed it the ‘working memory’) it’s flexible and dynamic in the way it works. STM has the following aspects:
Capacity- amount of information that can be stored.
Duration- amount of time that information can be stored
Encoding- the way sensory input is represented in the STM (images or sounds).
Short Term Capacity
The STM has limited capacity. According to Miller (1956) you have an immediate digit span- which is how many digits you can repeat after hearing them. Most people have a digit span of seven plus or minus two items. These can be chunks (one larger segment of information). An example of this is a PIN number being ‘9654’ in one chunk, yet ‘9 6 5 4’ is four separate ones.
KEY STUDY: Peterson & Peterson (1959)- Study of Duration of STM
The aim was to test how long STM lasts when rehearsal is prevented. Procedure: Participants were briefly shown a consonant Trigram (three letters e.g.. CPW). Participants counted backwards in threes a a specified number to stop them rehearsing the letters in their heads. After intervals of 3,6,9,12,15 and 18 seconds participants were asked to recall the Trigram. This was repeated several times with different letters.
Paterson & Peterson found that participants could recall about 80% of trigrams after 3 seconds and fewer trigrams were recalled the longer thetime intervals
The results suggest that the STM can only hold information for short periods of time- after 9 seconds correct recall significantly dropped. This suggests the STM maintains information for only short periods and repetition may allow information to be stored in the LTM. If people don’t make a conscious effort to reharse information it may be lost.
Evaluation:Trigrams are artificial things to remember and may not reflect what everyday memory is actually like. It may be that interference from earlier trigrams caused incorrect recall rather than decay of information.
Encoding in STM
Encoding is they way we visualise our information in pictures, icons or words in our heads. Substitution errors- where one item is mistaken for another such as letters that look similar being confused can indicate visual coding is used.
Conrad (1964) studied acoustic confusion by asking participants to listen to strings of letters being read aloud to them quickly. Conrad found participants often mistook certain letters for others such as ‘B’ for ‘D’ and ‘S’ for ‘X’. Participants found it more difficult to recall strings of acoustically similar letters suggesting letters in the STM form some sort of acoustic code.
KEY STUDY: Baddeley (1966)- Encoding in STM.
Baddeley explored the effects of acoustic and semantic encoding in STM. Participants were divided into four groups- each group heard a list of five words drawn from on of the following categories:
Acoustically similar words (man, mad, map)
Acoustically dissimilar words (pen, day, few)
Semantically similar words (great, big, large)
Semantically dissimilar words (hot, old, late)
Immediately after hearing the words they were asked to recall them in the correct order. This was done 4 times.
Baddeley found acoustically similar words were much harder to recall in correct order then dissimilar ones. Similarity of meaning had only a slight detrimental effect. The