Atkinson-Shiffrin memory model

Note that in this diagram, sensory memory is detached from either form of memory, and represents its devolvement from short term and long term memory, due to its storage being used primarily on a "run time" basis for physical or psychosomatic reference.

The Atkinson-Shiffrin model (also known as the Multi-store model, Multi-memory model and the Modal model) is a psychological model proposed in 1968 by Richard Atkinson and Richard Shiffrin^[1] as a proposal for the structure of memory. It proposed that human memory involves a sequence of three stages:

1. Sensory memory (SM)
2. Short-term memory (STM)
3. Long-term memory (LTM)

Summary

The original 2-stage model of the Atkinson-Shiffrin memory model; lacking the "sensory memory" stage, which was devised at a later stage in research

The multi-store model of memory is an explanation of how memory processes work. You hear, see, and feel many things, but only a small number are remembered. The model was first described by Atkinson and Shiffrin in 1968.

Sensory memory

The sense organs have a limited ability to store information about the world in a fairly unprocessed way for less than a second. The visual system possesses iconic memory for visual stimuli such as shape, size, colour and location (but not meaning), whereas the hearing system has echoic memory for auditory stimuli. Coltheart et al. (1974) have argued that the momentary freezing of visual input allows us to select which aspects of the input should go on for further memory processing. The existence of sensory memory has been experimentally demonstrated by Sperling (1960) using a [tachistoscope].

Short-term memory

Information is retained 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+ or -2 ‘chunks’ of information^[2] . STM also appears to mostly encode memory acoustically (in terms of sound) as Conrad (1964) has demonstrated, but can also retain visuospatial images. However in many cases STM can be at a semantic level.

Long-term memory

LTM 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. LT information seems to be encoded mainly in terms of meaning (semantic memory) as Baddeley has shown, but also retains procedural skills and imagery.

Memory may also be transported directly from sensory memory to LTM if it receives instant attention, e.g. witnessing a fire in your house. This is known as a "Flashbulb Memory". Another example of this is the fact most people can recall what they were doing on 11th of September 2001.

Also if information in the LTM is not rehearsed it can be forgotten through trace decay.

Criticisms

Linearity

Some argue that the Multi-Store model is too linear^{[citation needed]}, i.e., that it cannot accommodate subdivisions of STM and LTM memory stores^{[citation needed]} .

The concept of the "stream of memory" in this model has been suggested to lack internal consistency^{[citation needed]} , as, by definition, the stream of memory often discarded for newer information, often with little or emphasis on the salience on the new information^{[citation needed]} . A supposed example of this was found in the asymptote of control data, revealing primacy and recency effects (with information recalled better when presented early or late in the test stream), overshadowing the asymptote^{[citation needed]} . This suggests a need to explain decay processes in memory^{[citation needed]}. It has been suggested that the idea of 3 separate areas for memory storage may emerge from neuronal processes such as rates of firing^{[citation needed]} , as well as the idea of the "ionised sodium gate" model of action potentials^{[citation needed]}.

In the case of sensory memory, the model, which is psychological, does not provide a ready explanation for the observed asynchronous nature of neural activity occurring between anatomical structures^{[citation needed]} - an example of this would be the reference to sensory memory being used to perform physical processes such as motor function, which suggests that once an action is performed, it is remembered for 3 seconds and then begins a process of rapid decay^{[citation needed]} .

Monolithicity

The Atkinson-Shiffrin model distinguishes different forms of memory, but it does not take into account what information is presented^{[citation needed]} , nor does it take into account individual differences in subject's performance including an cognitive ability, or previous experience with learning techniques^{[citation needed]} .

Whilst case studies of individuals (such as Clive Wearing) have been reported indicating that memory can be severely damaged independent of at least some other cognitive capacities^{[citation needed]}, there is less support from case studies of developmental models for the supposed tri-partite memory structure^{[citation needed]} . Some have argued that autistic savant performance may violate predictions from the model, based on an ability to recall precise information without the need for rehearsal^{[citation needed]}, and without evidence for decay^{[citation needed]}.

Later Developments

The advent of the model provided an testable framework for subsequent work, and a strong stimulus for the experiemental study of human memory^{[citation needed]}. This has led to the model being superseded^{[citation needed]}. Newer models include the possibility for cases where short-term memory is impaired, but long-term memory is not (which is impossible in the basic model, as information can only become encoded in long-term memory after passing through the unitary short-term store.

Much recent work has focussed on the model proposed by Alan Baddeley, which distinguishes stores for phonological (speech-sound), and visuo-spatial information as well as episodic material, and proposes the existence of central executive processes, accessing these stores ^[3] .

Atkinson and Shiffrin also refrain from proposing any mechanisms or processes that might be responsible for encoding memories and transferring them between the three systems. The model is a hypothetical layout of the function of memory systems, but not in any way representative of a physical or biological basis of memory. Newer models have been created that can better account for these other characteristics, and a tremendous body of research on the physical layout of memory systems has emerged^{[citation needed]}.

See also

• Clive Wearing
• HM (patient)
• Richard Atkinson
• Richard Shiffrin

References

Baddeley A (April 1994). "The magical number seven: still magic after all these years?". Psychol Rev 101 (2): 353–6. doi:10.1037/0033-295X.101.2.353. PMID 8022967. 

External links

• Science aid: Multi Store Model Easy to understand yet comprehensive article on the model
• Simply Psychology webpage on multistore model