Baddeley's model of working memory

The multi-component model of working memory (also modular working memory model) was introduced in 1974 by Alan D. Baddeley and Graham J. Hitch. It provides a clarification of the previously popular model concepts from short-term memory ( Atkinson & Shiffrin, 1968) dar.

In the earlier memory models it was assumed that there is a unified system is the short-term memory that can only handle a task. However, Baddeley and Hitch have demonstrated in numerous empirical studies have shown that it is possible ( for example, the arithmetic of complex tasks or memorizing strings of words ) to perform multiple tasks of different types simultaneously. In contrast, they found that several tasks of the same type (for example visual tasks) can only very poorly or not run in parallel. From this they concluded that the short-term memory was not a unitary system but could be divided into several components.

The idea of the multi- component model

According to Baddeley and Hitch ( 1974) working memory consists of a central executive (central executive), which regulates the distribution of the priorities of the operations, which are under three memory modules:

• The phonological loop ( phonological loop),
• The visual-spatial notepad ( visuospatial sketchpad ) and
• The episodic buffer ( episodic buffer).

These are phonological for editing ( language-related ) or visual information, as well as responsible for holistic episodes for the assembly of information.

In 1974, the model was designed as a three-component model, in 2000 Baddeley added the episodic buffer component of the time.

The Individual Components

Phonological loop

The phonological loop is a component of the working memory model of Baddeley. He postulated that component, since it was assumed that visual-spatial information and linguistic information can not be processed in a component.

The object of the loop is to store language information, and change. This linguistic information is stored in a phonetic form ( phonetic form ). The capacity of the loop is limited, and is from one to two seconds. The phonological loop is divided into two sub-components - the passive phonological store and the articulatory control process.

The passive phonological memory is closely associated with speech perception and he stops in front of speech sounds until they fade. The articulatory control process can be viewed in the context of language production, ie, he freshened on linguistic information, and thus prevents its fading. This is done through the active inner speech. The process by which the information is repeated often by inner speech, called " Rehearsal".

Spoken information and written information have different access to the phonological loop. Spoken information can step right into the passive phonological store. Reasons for immediate storage are in the function of the passive memory. He stores the language in the form of sounds. Since the presented information already available in a phonetic form ( phoneme ), they must not be encoded into a phonetic form.

The written information is not, however, are present in phonetic form and must be encoded so that they can be kept in passive phonological store. This process will be illustrated by way of example. This one assumes, the number " 5", which appears on a screen for two seconds should be memorized. But to this visual stimulus in a phonetic form must be changed so that it can be stored in the passive phonological store. This change in the information carried by inner speech in the number ( verbalizing the number). Thus, the written language units ( graphemes ) be the number " 5" encoded into a phonetic form. This process should not be confused with the " Rehearsal". This phonetic form can now be stored in the passive phonological store.

The information that is stored in the passive phonological memory, can the " Rehearsal" are actively repeated and thus lead to a refreshing of the information and protect it from fading. If not, result in interference with new information that will eventually displace the old information. ( This process is equally applicable for spoken and written language. )

The construct of phonological loop should explain particular three effects: the effect of phonological similarity, the word length effect and the irrelevant speech effect.

The effect of phonological similarity describes that one can remember similar sounding letters and words worse than dissimilar. It is harder to repeat this information ( Rehearsal). Similarly: C, T, G, B, D; Dissimilar: X, S, K, M, Y

The word length effect describes that you can remember short words better than long words. It can be saved only as many words as can be seen in two seconds. This means that not as many long words can be read in two seconds as short. This means that the memory span is determined, because it may be less long words, short words are repeated as ( Rehearsal). However, this effect could not by other researchers, or only with Baddeleys original word list, replicated.

Irrelevant speech effect refers to the phenomenon that the performance drops at a verbal memory task, when is heard as background noise language, which suggests a phonological loop. However, the effect can also show up when used as a distractor rather than language only tones with varying frequency.

Spatio- visual notebook

The visual-spatial notepad ( visuo -spatial sketch pad) is responsible for the temporary storage of spatial and visual information system with limited capacity. According Baddeley it is also responsible for the manipulation of visual and spatial information (e.g., "mental imaging" ). The limited capacity is most obvious on the effects of change blindness, in which we can notice only a certain number of objects.

The processing systems for spatial ( eg object position, movement ) and visual (eg shape, color) information are separated. This allows the spatial perception hardly disturb and vice versa by visual tasks.

Newer Awh and Jonides of ( Awh & Jonides 2001) carried out investigations were concerned with the functioning of spatial working memory ( " Notepad "). This amazing parallels to the location-based attention could be found. Thus it was found that with the shift of the spotlight of attention diminished considerably the spatial memory performance. Furthermore, it became clear that in places that should be remembered visual stimuli can be processed better than other places. This is also been proven for increased activity in the contralateral visual cortex based imaging techniques (EEG, fMRI). Such phenomena were already known for the location-based attention and thus create a functional connection between the two processes close.

The assumption that spatial and visual processes are separated from each other, was also confirmed by a PET study by Smith. This was for the double dissociation following becomes clear: while spatial tasks demand ( specifically to the accumulation in the brain ), especially the right brain hemisphere, for object recognition tasks, the left hemisphere is mainly active. In both tasks, the prefrontal cortex is of great importance. Other important areas include the parietal cortex, occipital cortex, premotor cortex, temporal lobe and the frontal lobe.

Episodic buffer

With time, Baddeley discovered effects that can no longer be using the three- component model to explain. Usually you can remember about 5 words, if the words but have a relationship (eg, form a set, see Chunking ), you can remember about 16 words. The original idea that because long-term memory is involved, had to be discarded because people with damaged short-term memory functioning and long-term memory can only remember about 5 words. Long-term memory is so obviously not involved.

To explain Baddeley added the episodic buffer to his model in 2000. It is a multi-modal system with a limited memory capacity, it may store both visual and phonological information in the form of "episodes".

Central executive

The central executive is the most important, but so far the least studied component of the working memory model of Baddeley. In the original model, it was considered as a pool for all processes that can not be clearly categorized as one of the subsystems were ( Anderson, 2001; Baddeley, 1983, 2003). Your essential functions saw Baddeley is to establish a connection to the long-term memory, to focus attention, to move and to share ( Baddeley, 2003). In experiments on divided attention, in which the subjects had to perform two different processing methods which claimed the subsystems at the same time (for one, they had to memorize a series of numbers, on the other hand they should simultaneously pursue a spot with the eyes) cut patients with Crohn's Alzheimer significantly worse than healthy people of comparable age, which in turn were not worse than young subjects. This implies that a functioning working memory is essential for the modulation of attention ( Baddeley, 2003). Because of the close relationship between working memory and attention Baddeley model is also referred to as "working -attention " model (Shah & Miyake, 1999). The operation of the central executive is illustrated by trying the multiplication problem 37 * 28 to solve in your head. There are two strategies: the task either one imagines Visualize and expects almost as if we solve the problem in writing, or the task is called again and again before and calculated constantly verbalisierend, step by step. The first option would involve the visual-spatial notepad with, the second is the phonological loop. The central executive has thereby save the task, what ever the task to retrieve information from LTM ( for example, that 7 * 8 = 56 ), to remember Unearned ( 5 from 56 for example) and to track finally, how far advanced the solution of the task ( Anderson, 2001).

Some authors have criticized that a further, limited in their capacity memory component would be necessary for these complex processes. Baddeley, inspired by other works, therefore supplemented his 2001 model to the episodic buffer ( episodic buffer). This can be considered a stand-alone component, but is more of a controlled by the central executive memory which stores information into coherent episodes binds ( Baddeley, 2003). Its multidimensional coding allows him further to integrate the information of the sub-systems, thereby making it easier for the central executive to coordinate them. By pooling information about episodes of memory span increases to records with more than 15 words. In comparison, its capacity is limited to five to six individual, non-contiguous words ( Baddeley, 2003). This fact is very important for building mnemonic while learning, where different information can be bundled into one easy-to -remember episode.

Which could previously only implied connection to the long-term memory arises Baddeley as a kind of " download " before, stored in the information from long-term memory in the episodic buffer ( Baddeley, 2003). The central executive is localized in some areas of the frontal and the parietal lobe. Evidence of this was found in experiments in fMRI, in which the subjects either a task ( "Count of 100 in three steps backwards! " ) Exported or should generate a random sequence of button presses or number sequences ( Baddeley, 2003).

Findings

Information in working memory is lost after a split second when it is not actively maintained (so-called rehearsal ). Visual information go much faster than acoustic lost if they are not verbalized.

The working memory model has been supported by findings of Logie et al. (1990) confirmed. It was found in two experiments that verbal distraction tasks affects mainly the work in the phonological loop and especially to limit visual distraction tasks, the capabilities of the spatial visual notepad. A verbal task, however, has only a small influence on the visual system and vice versa. Thus, the existence of two different subsystems could be demonstrated in working memory.

Working memory is (as opposed to long-term memory ) capacity greatly limited. In general, it can contain 7 ± 2 elements ( Miller number). The amount of these elements, which can be called up and processed at the same time at the same time is called a span. The capacity limitations of working memory is treated in detail in the Cognitive Load Theory.

Evidence from modern Volitionspsychologie show that the memory for intentions, the so-called intention memory, relies on structures of working memory. In a memorandum of intention memory is maintained for a longer time before they can reach for execution.

The neural correlate of the central executive of working memory is suspected, especially in the prefrontal cortex.

Studies have shown that the individual components of the phonological loop have a neural correlate in the brain. Increased activity was found in the left frontal lobe located in Broca's area, which plays a role in language production and thus is related to the articulatory control process. Activation of the inferior parietal cortex had tasks to sequence in which words should be noted.

This module oriented theory are (eg, the Embedded Processing Model of Working Memory to Nelson Cowan and model of Engle ) compared to newer, more process-oriented theories. These theories is considered by the attentional resources and distribution of the associated activation of distributed neural networks.

Criticism

" Phonological loop ", " visual notebook " and " episodic buffer " are just new names for well-known functions. The operation of the " central executive ", the key component of Baddeley model, is not explained. The model explains only the passive "slave systems ". On the processes that occur between the individual modules, the model does not address. Furthermore, Baddeley model to the explanation of how auditory and visual-spatial information is processed is limited. It does not deal with the processing of other stimulus qualities.