Phonological loop and visuospatial sketchpad are subsystems that hold information passively while central executive is the main drive of the memory process (Baddeley and Hitch, 974). However, the model did not describe on the effects of stored knowledge on the memory. Thus, a new component, episodic buffer, was added as an account of the relationship between long-term memory and working memory, integration of information from other components, and the additional storage capacity (Baddeley, 2000). Although Baddeleys (2000) working memory model is known as most influential working memory models in modern psychology history, it might not be the most suitable modal in explaining humans working memory for three reasons, the validity of phonological loop, ambiguity of the memory capacity, the vagueness of episodic buffer and the compatibility of visuospatial sketchpad.
This essay will briefly describe basic concepts of each components in Baddeleys (2000) working memory model and evaluate the components by examining whether the functions of each component is comprehensive. Firstly, phonological loop which is said to be the most well-developed component is not comprehensive in describing the implications of its functions. It should first be understood that there are two main constituents of the loop, phonological store and articulatory control process (Baddeley, 2000). Phonological store holds verbal and acou
stic information temporarily until the information decay, which takes about 2 seconds, while articulatory control process functions to translate visual information to speech-like codes and to counteract the decay process of information by refreshing traces in the phonological store (Baddeley, 2000). Thus, it could be said that the decay of the information could be prevented by rehearsing the items; Rehearsal is essential to prevent information from fading. However, recent research found that rehearsal and decay have an ambiguous trade-off (Nairne, 2002). It is proposed that working memory would decay when the items are not rehearsed, and this is due to the time-based word-length effect which shows that words with shorter time for pronunciation are easier to be recalled (Baddeley, Thomson, and Buchman, 975). Yet, Lovatt, Avons and Masterson (2000, 2002) found out that there was a reverse word-length effect from the outcome of the replicated experiment as the percentage of recalling lengthier words was higher. It is seemed that only particular sets of words could produce a positive outcome for the experiment, and the inconsistency of the experiment outcomes obtained by researchers may show that the theory is not significant. Apart from that, episodic buffer as a relatively innovative element in the working memory model is subjected to the uncertain validity due to the lack of sound experimental research.