Human Memory
Lesson 14
Human Memory Models Working Memory Model Produced by
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Working Memory Model • One of the criticisms of the multi-store model is that it is too simplistic & that it assumes the STM & LTM act as unitary stores. • There seems to be more support for the idea that both memory stores are divided into different components and that these components have different functions. • The first people to explore the notion of a multicomponent short term store was Baddeley and Hitch (1974).
• They conducted a dual task study in which participants were given digit strings to rehearse while, at the same time, carry out verbal reasoning tasks similar to those below.
• Imagine yourself trying to do these reasoning tasks and at the same time rehearsing a string of digits –you probably think that this would be very difficult if not impossible. • However, participants in the study were able to recall six-digit strings and perform accurately on the reasoning task. • This finding is not compatible with Atkinson & Shiffrin’s view of short term store that can hold only small amount of information.
• Instead the findings from this study suggests that STM, or working memory as Baddeley & Hitch called it, consists of several components that can work independently of one another and can handle more than one task at a time. • Baddeley & Hitch concluded on the basis of this and other studies that STM is a flexible and complex system that consists of a central control mechanism assisted by a number of slave systems. The model has been modified slightly in the light of experimental studies.
Central executive: • The central executive is the most important component in the model for monitoring and coordinating operation of the slave systems. • It is flexible in that it can process information from any modality and also has some storage capacity, but limited. • It seems to play a major role in attention, planning and synthesizing information, not only from the slave systems but also from the LTM.
Phonological loop: • The phonological loop stores a limited number of sounds for brief periods and can be thought of as an inner ear. • It is thought to consist of two components. One is the phonological store (inner ear) that allows acoustically coded items to be stored for a brief period. • The other component is the articulatory control system (the inner voice ) that allows subvocal repetition of items stored in the phonological store.
Visuo-spatial sketch pad: • The visuo - spatial sketch pad stores visual and spatial material and can be thought of as an inner eye. • Like the phonological loop, it has limited capacity, but the limits of the two systems are independent. • In other words it is possible, for example, to rehearse a set of digits in the phonological loop while at the same time making decisions about the spatial layout of a set of letters in the visuo spatial sketch pad.
• If you are like most people, you will have formed a mental image of your home and counted the windows either by imagining the outside of your house or by walking through the house room by room.
• The image will be set up and manipulated in your visuo-spatial sketch pad and the tally of the windows will be held in the phonological loop as you count them sub - vocally. • The whole operation will be supervised by the central executive, which will allocate the tasks and recognise when the final total has been reached.
Evaluation of the Working Memory Model • The working memory model has a number of advantages over the concept of STM when compared to the multi store model. It can account for the ability to store information briefly, while at the same time actively processing the material.
• There is research that supports the existence of the phonological loop slave system. • For example, Baddeley et al. (1975) conducted a series of studies that investigated the word-length effect by repeating an irrelevant sound ‘la, la, la , …’ (articulatory suppression), the word lengtheffect disappeared (i.e. short words were recalled no better than long words).
• It is assumed that the articulatory suppression task fills the phonological loop and therefore takes away the advantage of rehearsal. • Since some words could be recalled, it is likely that the central executive takes over the recall task.
• The visuo-spatial store has not been investigated in the same depth as the phonological store, but there is experimental evidence that supports its existence. • For example, Baddeley et al. (1973) gave participants a simple tracking task that involved holding a pointer in contact with a moving spot of light. • At the same time, participants were asked to perform an imagery task. Participants were asked to imagine a block capital letter ‘F’ .
F
• After imagining a block letter F, participants were asked starting at the bottom left hand corner, to classify each angle as a ‘yes’ if it included the bottom or top line of the letter and as a ‘no’ if it did not. • Participants found it very difficult to track the spot of light and accurately classify the angles in the letter imagery task.
• However, they were perfectly capable of carrying out the tracking task in conjunction with the verbal task. • This suggests that the tracking and imagery task were competing for the limited resources of the visuo-spatial sketch pad. • Whereas the tracking task and the verbal task were making use of the separate components of the visuo-spatial sketch pad and phonological loop respectively.
• The working memory model has proved to be influential and is still being developed and expanded. The main weakness is that the component (central executive) which is the most important but yet we know the least about. • Richardson (1984) argues that there problems specifying the precise functioning of the central executive. • He believes the terminology is vague and can be used to explain any kind of results.