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