Short-term Memory is the type of memory where information is selected by attention from sensory memory, may pass into short term memory (STM). This allows us to retain information (acoustically) long enough to use it, e.g. looking up a telephone number and remembering it long enough to dial it. Peterson and Peterson (1959) have demonstrated that STM last approximately between 15 and 30 seconds, unless people rehearse the material, while Miller (1956) has found that STM has a limited capacity of around 7+/-2 ‘chunks’ of information. STM also appears to mostly encode memory acoustically (in terms of sound) as Conrad (1964) has demonstrated, but can also retain visuo-spatial images. However in many cases STM can be semantic.
Long-term memory is the third and the last type of memory that provides the lasting retention of information, from minutes to a lifetime. Long term memory appears to have an almost limitless capacity to retain information, but it could never be measured as it would take too long. Long term information seems to be encoded mainly in terms of meaning (semantic memory). Memory may also be transported directly from sensory memory to LTM if it receives instant attention.
In addition to this, if information in the LTM is not rehearsed it can be forgotten through trace decay.
The strength of the Multi-store Model of Memory is that STM/LTM difference is also seen in sufferers of Korsakoff’s syndrome. The weakness of Multi-store Model of Memory is that there is more than one STM store. Shallice and Warrington (1974) showed that patient KF only had verbal STM problems. Non-verbal sounds (like doorbells etc.) were remembered normally.
The Working Memory Model
Working Memory Model it’s a more complex and dynamic STM. All the information you are currently thinking about is held the working memory, i.e. what you are working on. The capacity of this memory model is limited.
The Central Executive ‘manages’ the system – the other modules are ‘slaves’ to this one. It decides what needs to be done and when.
The Phonological Loop is an auditory store, rehearsing information to prevent loss and decay. It has two parts: Phonological store: the ‘inner ear’ and the Articulatory loop: the ‘inner voice’.
The Visuo-spatial Sketchpad is the ‘inner eye’. Organises information visually, as you would by sketching them out on paper.
The strength of The Working Memory Model is that some brain-damaged patients are good at spatial but not visual tasks, evidence that we have a visual and spatial system (Farah et al 1988). The weakness of The Working Memory Model is that there is little evidence for the role of the central executive as most research is done on the other components.
Bibliography
- New 2008 AQA ‘A’ Specification – AS level Psychology written by Nigel Holt and Rob Lewis.
- Google search