Atkinson-Shiffrin memory model

  The Atkinson-Shiffrin model, Multi-store model or Multi-memory model is a psychological model proposed in 1968 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)

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Summary

  The multi-store model of memory is an explanation of how memory processes work. You hear and 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 selected by attention from sensory memory, may pass into short term memory (STM). This allows us to retain information 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 visuospatial images.

Long-term memory

LTM provides the lasting retention of information and skills, 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. Such as the witnessing of a fire in one's home.

Criticisms

Linearity

Some may argue that the Multi-Store model is much too linear, and does not accommodate for the subdivisions of STM and LTM memory stores -- particularly, its structure does not parallel well within the neurological explanations of where and how memory is stored; the model suggesting that memory would be purposely disregarded by physiological processes and stored in a linear memory sequence -- only being able to handle or deal with memory which has been "added" to this stream, which is juxtaposed to the composition of neurons including axons and dendrites.

The concept of the "stream of memory" in this model also has internal criticism, which would mean that by definition, its own stream of memory was inconstant and often discarded for newer information with relatively no emphasis or importance on the information, which precedes it. A supposed example of this was given in the control tests for the studies; the asymptote of the data largely revealing that the primary and recency areas of data were well remembered, overshadowing the asymptote. While this may be an affirmation of the decay of memory and to a small extent, the idea of 3 separate areas for memory storage would be juxtaposed to the principle of intensity and rate of firing within neurons, as well as the idea of the "ionised sodium gate" model of action potentials.

In the case of sensory memory, the model does not acknowledge the asynchronous nature of the neural activity which occurs between anatomical structures, such as the relationship between a neuron and a motor end-plate - 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.

Monolithicity

While the model deals with the several forms of memory in its model, it does not take into account the way in which the information is presented, nor does it take into account biological, or internal factors which may interfere with an individual's ability to respond or understand the experiment - including an individual's cognitive ability, or previous experience with learning techniques.

Whilst there is studies to suggest that some people, such as Clive Wearing have limited memory capacity, it is not enough evidence in itself to suggest that the brain has 3 separate memory stores within its structure. The reasoning is that whilst these cases can be somewhat explained by the multi-store model, other cases such as those of autistic savants, completely disband the theory of repetition and rehearsal within the multi store model, due to their ability to be able to recall precise figures with clarity and lucidity without the need for rehearsal; showing no process of decay, nor any other factors mentioned in the original model.

Had the model included internal factors which influenced each stage of the memory process, it would have been somewhat more credible in explaining such phenomena.

Later Developments

This model provided an important framework for learning and memory theories to evolve from, but a number of problems with it have been cited since. Since each element in the model builds off the one preceding, it cannot explain the rare situations where short-term memory is impaired, but long-term memory is not. According to this model, information that can't make it through short-term memory has no way to become encoded in long-term memory.

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 "map" of memory systems.

Many 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. As the oldest and simplest model, this is can no longer be considered entirely accurate or comprehensive.

The rehearsal loop also must be included in the transfer of memory into LTM from the STM, it is said that for things to be transferred correctly they must negate the rehearsal loop to ensure full remembrance.

References

Atkinson, R.C. & Shiffrin, R.M. (1968) Human memory: A proposed system and its control processes. In K.W. Spence and J.T. Spence (Eds.), The psychology of learning and motivation, vol. 8. London: Academic Press.

See also

• HM (patient)
• Clive Wearing