Baddeley's working memory model

from Wikipedia, the free encyclopedia

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 represents a more precise definition of the model concepts of short-term memory .

In the earlier memory models it was assumed that short-term memory is a uniform system that can only process one task at a time. However, Baddeley and Hitch were able to demonstrate in numerous empirical studies that it is possible to carry out several tasks of different types (e.g. calculating complex tasks or memorizing sequences of words) at the same time. However, they found that several tasks of the same type (e.g. visual tasks) can only be carried out very poorly or not at all in parallel. From this they concluded that short-term memory is not a uniform system, but can be divided into several components.

The idea of ​​the multi-component model

Schematic representation of Baddeley's working memory model

Alan Baddeley (2002, 2003) was able to demonstrate four components of the working memory:

These are responsible for processing phonological (language-related) or visual information and for combining information into holistic episodes.

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

The components in detail

Phonological loop

Schematic representation of the phonological loop with the two components

The phonological loop is a component of the Baddeley working memory model. He postulated this component because he assumed that visual-spatial information and linguistic information cannot be processed in one component.

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

The passive phonological memory is closely related to speech perception and holds speech sounds until they fade. The articulatory control process can be viewed in the context of language production, that is, it refreshes linguistic information and thus prevents it from fading. This happens through active inner speaking. The process in which the information is repeated frequently through internal speaking is called “rehearsal”.

Spoken information and written information have different access to the phonological loop. Spoken information is immediately stored in the passive phonological memory. The reasons for the immediate storage are the function of the passive memory. It saves the language in the form of sounds. Since the presented information already in phonetic form ( phoneme present), they must be no longer encoded in a phonetic form.

However, the written information is not in phonetic form and must be encoded so that it can be kept in passive phonological memory. This process should be illustrated with the help of an example. To do this, it is assumed that the number “5”, which appears on a screen for two seconds, should be noted. To do this, however, this visual stimulus must be changed into a sound form so that it can be stored in the passive phonological memory. This change of information takes place through internal speaking of the number (verbalizing the number). This encodes the written language units ( graphemes ) of the number “5” in a phonetic form. This process should not be confused with “rehearsal”. This phonetic form can now be stored in the passive phonological memory.

The information that is stored in the passive phonological memory can be actively repeated by the rehearsal and thus refresh the information and protect it from fading. If this does not happen, interference with new information occurs, which ultimately displaces the old information. (This process is equally applicable to spoken and written language.)

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

The phonological similarity effect describes the fact that letters and words that sound similar are more difficult to remember than dissimilar ones. It is more difficult to repeat this information (rehearsal). Similar: C, T, G, B, D; Dissimilar: X, S, K, M, Y

The word length effect describes that short words are easier to remember than very long words. Only as many words can be stored as can be read in two seconds. This means that not as many long words can be read in two seconds as short ones. This also determines the memory span, because fewer long words than short words can be repeated (rehearsal). This effect could not be replicated by other researchers, or only with Baddeley's original word list.

Irrelevant speech effect describes the phenomenon that the performance of a verbal memory task is reduced if speech can be heard as background noise, which speaks for a phonological loop. However, the effect can also be shown if only tones with changing frequencies are used as distractors instead of speech.

Spatial-visual notepad

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

The processing systems for spatial (e.g. object position, movement) and visual (e.g. shape, color) information are separate. The spatial perception can hardly be disturbed by visual tasks and vice versa.

More recent studies carried out by Awh and Jonides dealt with the functioning of spatial working memory (“notepad”). Astounding parallels to location-based attention could be found. It was shown that with the shift of the spotlight of attention, the spatial memory performance decreased considerably. Furthermore, it became clear that visual stimuli can be processed better in places that should be remembered than in other places. This has also been demonstrated in the increased activity in the contralateral visual cortex using imaging methods ( EEG , fMRI ). Such phenomena were already known for location-based attention and thus suggest a functional connection between the two processes.

The assumption that spatial and visual processes are separate from one another was also confirmed by a PET study by Smith. The following became clear for the double dissociation : While spatial tasks (aimed at storage in the brain) mainly require the right brain hemisphere, the left brain hemisphere is mainly active in object recognition tasks. The prefrontal cortex is of great importance in both tasks. Other important areas are: parietal cortex, occipital cortex, premotor cortex, temporal lobes, and the frontal lobes.

Episodic buffer

Over time, Baddeley discovered effects that the three-component model can no longer explain. Normally you can remember about 5 words, but if the words have a context (e.g. form a sentence, see Chunking ), you can remember about 16 words. The original idea that long-term memory is involved in this had to be discarded, as people with damaged short-term memory and functioning long-term memory can only remember about 5 words. Long-term memory is obviously not involved.

To explain this, Baddeley added the episodic buffer to his model in 2000. It is a multimodal storage system with limited capacity, it can store both visual and phonological information in the form of "episodes".

Central executive

The central executive is the most important, but so far least explored, component of Baddeley's working memory model. In the original model, it was viewed as a pool for all processes that could not be clearly assigned to one of the subsystems (Anderson, 2001; Baddeley, 1983, 2003). Baddeley saw their essential functions as establishing a connection to long-term memory (LZG), focusing, moving and sharing attention (Baddeley, 2003). In experiments on divided attention, in which the test subjects had to carry out two different processing processes that required the subsystems at the same time (on the one hand they had to memorize a series of numbers, on the other hand they were supposed to follow a point of light with their eyes at the same time) patients with disease cut Alzheimer's was significantly worse than healthy people of comparable age, who in turn were no worse than young subjects. This implies that a functioning working memory is essential for attention modulation (Baddeley, 2003). Because of this close connection between working memory and attention, Baddeley's model is also known as the “working-attention” model (Shah & Miyake, 1999). The way the central executive works is illustrated by trying to solve the multiplication problem 37 * 28 in your head. There are two solution strategies: either you imagine the task visually and calculate as if you were solving the task in writing, or you repeat the task to yourself over and over and calculate, constantly verbalizing, step by step. The first variant would include the visuospatial notepad, the second the phonological loop. The central executive has the task of storing what the task is, calling up information from the LZG (for example, that 7 * 8 = 56), memorizing transfers (for example the 5 from 56) and finally tracking it, how far the solution of the problem has progressed (Anderson, 2001).

Some authors criticized the fact that these complex processes require an additional memory component with limited capacity. Baddeley, also inspired by other work, therefore added the episodic buffer to his 2001 model. This can be viewed as an independent component, but is more of a memory controlled by the central executive that ties information together to form coherent episodes (Baddeley, 2003). Its multidimensional coding also allows it to integrate the information from the subsystems, which makes it easier for the central executive to coordinate this. By bundling information into episodes, the memory span increases to sentences with more than 15 words. In comparison, its capacity is limited to five to six individual, disjointed words (Baddeley, 2003). This fact is very important for building donkey bridges when learning, where various information is bundled into an easy-to-remember episode.

Baddeley imagines the connection to long-term memory, which was previously only implied, as a kind of "download" in which information from long-term memory is stored in the episodic buffer (Baddeley, 2003). The central executive is located in some areas of the frontal and parietal lobes. Evidence for this was found in experiments in fMRI, in which the test persons either performed a task (“Count backwards from 100 in three steps!”) Or were asked to generate a random sequence of button presses or number sequences (Baddeley, 2003).

Findings

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

The working memory model has been confirmed by findings from Logie et al. (1990). It was found in two experiments that verbal distraction tasks primarily impair the work in the phonological loop and visual distraction tasks particularly restrict the capabilities of the spatially visual notepad. A verbal task, on the other hand, has only a minor influence on the visual system and vice versa. In this way, the existence of two different subsystems in working memory could be proven.

The working memory (in contrast to the long-term memory ) is strongly capacity limited . Usually it can contain 7 ± 2 elements ( Miller number ). The amount of these elements that can be accessed and processed at the same time is called the memory span . The capacity constraints of working memory are discussed in detail in the Cognitive Load Theory .

Findings from modern volitional psychology show that the memory for intentions, the so-called intention memory, draws on the structures of the working memory . An intention is kept in the intention memory for a longer period of time until it can be executed.

The neural correlate of the central executive branch of working memory is suspected to be primarily in the prefrontal cortex .

Research has shown that the individual components of the phonological loop have a neural correlate in the brain. Increased activity was found in Broca's area in the left frontal lobe , which plays a role in speech production and is therefore related to the articulatory control process. Activation of the inferior parietal cortex resulted in tasks requiring words to be memorized.

This module-oriented theory contrasts with more recent, process-oriented theories (e.g. the Embedded Processing Model of Working Memory according to Nelson Cowan and the model by Engle ). These theories assume the distribution of attention resources and the associated activation of distributed neural networks.

criticism

This article or the following section is not adequately provided with supporting documents ( e.g. individual evidence ). Information without sufficient evidence could be removed soon. Please help Wikipedia by researching the information and including good evidence.

“Phonological loop”, “visual notepad” and “episodic buffer” are just new names for familiar functions. The functioning of the “central executive,” the most important part of Baddeley's model, is not explained. The model only explains the passive "slave systems". The model does not deal with the processes that take place between the individual modules. Furthermore, Baddeley's model is limited to explaining how auditory and visual-spatial information is processed. It does not deal with the processing of other stimulus qualities.

literature

  • JR Anderson: Cognitive Psychology. 3. Edition. Spectrum, Heidelberg 2001.
  • AD Baddeley: That's how people think. Knaur, Munich 1988.
  • AD Baddeley: Exploring the central executive. In: Quarterly Journal of Experimental Psychology. 49A (1), 1996, pp. 5-28, doi : 10.1080 / 713755608 .
  • AD Baddeley: The episodic buffer: A new component of working memory? (PDF; 712 kB). In: Trends in Cognitive Sciences. 4 (11) 2000, pp. 417-423, doi : 10.1016 / S1364-6613 (00) 01538-2 .
  • AD Baddeley: Is working memory still working? ( Memento from November 1, 2004 in the Internet Archive ) (PDF; 237 kB). In: European Psychologist. 7 (2), 2002, pp. 85-97, doi : 10.1037 / 0003-066X.56.11.851 .
  • AD Baddeley: Working memory: Looking back and looking forward. ( Memento from January 18, 2012 in the web archive archive.today ) In: Nature Reviews Neuroscience . 4 (10), 2003, pp. 829-839, doi : 10.1038 / nrn1201 .
  • AD Baddeley: Working Memory: Theories, models, and controversies. In: Annual Review of Psychology. 63 (1), 2012, pp. 1–29, doi : 10.1146 / annurev-psych-120710-100422 .
  • AD Baddeley, GJ Hitch: Working memory. In: GH Bower (Ed.): The psychology of learning and motivation: Advances in research and theory. Vol. 8, Academic Press, New York 1974, pp. 47-89.
  • M. Eysenck, M. Keane: Cognitive Psychology: A Student's Handbook. Psychology Press, East Sussex 2005.
  • RH Logie, GM Zucco, AD Baddeley: Interference with visual short-term memory. In: Acta Psychologica. 75 (1), 1990, pp. 55-74, doi : 10.1016 / 0001-6918 (90) 90066-O .
  • J. Müsseler, W. Prinz (Ed.): General Psychology. Spectrum, Heidelberg 2002.
  • P. Shah, Miyake, A .: Models of working memory: An introduction. In: A. Miyake, P. Shah (Eds.): Models of working memory: Mechanisms of active maintenance and executive control .. Cambridge University Press, New York 1999., 1999
  • EE Smith, J. Jonides: Working memories in humans: Neuropsychological evidence. In: M. Gazzaniga (ed.): The cognitive neuroscienses: The biology of the mind. MIT-Press, Cambridge 1995, pp. 1009-1020.

Individual evidence

  1. ↑ RC Atkinson , RM Shiffrin : Human memory: A proposed system and its control processes. In: KW Spence, JT Spence (Ed.): The psychology of learning and motivation: Advances in research and theory. Vol. 2, Academic Press, New York 1968, pp. 89-195.
  2. ^ Richard J. Gerrig: Psychology . 20th updated and expanded edition. Pearson, S. 248 .
  3. ↑ E. Awh, J. Jonides: Overlapping mechanisms of attention and spatial working memory. (PDF; 126 kB). In: Trends in Cognitive Sciences. 5 (3), 2001, pp. 119-126.