Evaluation of Working memory model

Strengths

The working memory model is high in face validity, this means that the model seems plausible. In this case, it seems plausible because it fits with everyday experience of manipulating information when solving problems, with short term memory as a dynamic process rather than a static store. For example, Baddeley (1997) suggests that mentally counting the number of windows in your house (or flat) demonstrates the operations of working memory. Normally a person will imagine each room in turn, forming a mental image of each window (Visuospatial sketchpad), they will count using the phonological loop to rehearse the numbers and this will all be coordinated by the Central Executive.

Another advantage of the Working Memory model is that verbal rehearsal is not necessary for all types of information – just verbal strings - this fits better with our everyday experience. For example, we do not have to rehearse everything that happens to us because events are processed by the episodic buffer.

Empirical Evidence

Baddeley (1975) found that participants' memory span for visually presented one-syllable words was greater than for polysyllabic words (words with more than one syllable). This suggests that the articulatory loop is only able to hold limited number of syllable chunks. However, later studies showed that memory span for words like “Cricket” and “Bishop” was greater than for words like “Harpoon” and “Friday”. Harpoon and Friday have long vowel sounds and take longer to say, which suggests that memory span is limited by time (about 2 seconds) rather than number of chunks. This supports the idea that the articulatory control system is a time based rehearsal loop.

Research where verbal rehearsal is prevented by using articulatory suppression tasks has also supported the model. Baddeley and Lewis (1981), for example, visually presented sentences to participants while they performed an articulatory suppression task (e.g., repeating 'hi-ya' over and over again) and asked them to spot mistakes in the sentences. They found that sentences with syntactic anomalies (Words in the wrong order; e.g., The trees flew up into the birds) were detected less often than sentences with semantic anomalies(meaning does not make sense; e.g., 'The anxious woman was cycling by the man's laughter'). This seems to indicate that the articulatory loop is important in holding information regarding the order of words. It also shows that working memory is a complex dynamic system, rather than a static STM store.

Weaknesses of Working Memory Model

The most important weakness of the working memory model is that the functions of the central executive are vague and difficult to test. For example, Baddeley claims that the central executive has a limited capacity; however, how this capacity can be measured independently of the other components is unclear. Baddeley also claims that the CE can be divided into subsystems; however they have not yet been identified and it is difficult in practice to determine which processes that control the slave systems are part of the central executive and which are part of other systems, such as language

Visual spatial sketchpad example

Shepard and Feng (1972)

Aim - To discover the VSS

Procedure - Shepard and Feng used shapes such as the opening of a cube and asked P#s to imagine folding these flat shapes to form a cube with the grey area as the base and then to decide whether in the finished cube, the arrows on the open shape would meet.

Results - Found that visual images work in a very similar was to real life perception.

Conclusion - The VSS is used in tasks like the above for the temporary storage and manipulation of visual patterns and spatial movement. They require concentration. People are likely to find it difficult to do two tasks simultaneously

Baddeley, Thomson and Buchanan (1975)

Aim - To find out the existence of the phonological loop (Inner voice)

Procedure - P's were given word list for brief exposures and asked to write them down in serial order.

• Condition A - 5 words from a pool of one syllable, English words such as palm, twice. 
• Condition B - 5 words from a list of polysyllables such as organisation, association. 

Results - Average correct recall over several trials showed that the shorter words had greater recall. This was called the 'word length effect' 

Conclusion - Lab experiment in repeated measures was well controlled but could be criticized that longer words are simply less familiar than shorter words and therefore harder to recall.

- Consent. 

Working memory model - The components.

Baddely and Hitch believed that the STM store in the Multistore Model was too simplistic: they thought that short term memory was not a passive store, but several active processes that manipulate information.

Central Executive

The central executive is considered the most important part of working memory, because it controls attention and coordinates the actions of the other components, it can briefly store information, but has a limited capacity. The central executive is modality free, which means that it can store information in any sense. This core component has two slave systems which work independently. 

Phonological Loop

The phonological loop consists of two parts, the articulatory control system and thephonological store:

• Articulatory Control System (The Inner Voice) The articulatory control system rehearses information verbally and has a time based capacity of about 2 seconds. It is helpful to think of it as the system that you use to mentally rehearse information by repeating it over and over again.
• Phonological Store (The Inner Ear) The phonological store uses a sound based code to store information, but this information decays after about 2 seconds, unless it is rehearsed by the articulatory control system. The phonological store receives its input either directly from the ears or from long term memory. If you imagine your favourite piece of music you are using your phonological store.

Visuospatial Sketchpad

The visuospatial sketchpad stores and manipulates visual information, input is from the eyes or long term memory. if you imagine an object and then picture it rotating you are using your visuospatial sketchpad.

Strengths and weaknesses of the multi-store model

- There is a considerable body of evidence supporting the distinction between the different types of memory ( ie sensory, short term and long term). Much of the evidence is based of lab studies but there is also important case study research on people whose memories have been affected by disease or accident.
- The multistore model was important and influential when it was first proposed, however, subsequent research has revealed a number of weaknesses. The model is too simplistic (reductionist) and inflexible to explain fully the complexities of human memory. It is also very deterministic.

Encoding of LTM- Baddeley (1966)

Aim - Investigate the nature of LTM coding.

Procedure - Baddeley constructed a pool of short, familiar words for each of four catagories, and agreed with Conrad. Baddeley modified his experiment to test LTM. He extended the length from 5 words to prevent rehearsal by interrupting them after each presentation. Each list was presented four times and then recalled after a 20 minute interval.

Results - Under these conditions, he found that acoustic similarity had no affect on recall but that words with similar meaning were poorly recalled

Conclusion - LTM codes mainly semantically

Evaluation - Lab experiment so it is therefore artificial
- No serious ethical issues
- Consent is needed.