The working memory model (WMM) has four components. The central executive controls and monitors the operation of the other 3 components. It also allocates attention. The phonological loop is sub-divided into 2 smaller components, the articulatory control system, where information is rehearsed sub vocally or in the inner voice and the phonological store where speech is held for a very brief duration in the inner ear. The third component is the visuo spatial sketchpad which deals with visual information obtained by the sensory organs (eyes) or recalled from the LTM. The fourth component is the episodic buffer which acts as a store for visual and acoustic data and the retrieval of long term memory. It has an unlimited duration and capacity.
Evidence that proves that the phonological loop and articulatiory process exist is the ‘Word-length effect’. The word length effect describes the fact that people cope better with short words in the working memory (STM) than long words. Baddeley said the phonological loop can hold information for about 1-2 seconds. So long words are quite hard to remember compared to shorter words, however if the participants are prevented from rehearsing the words sub vocally by repeating an the word length effect disappeared irrelevant sounds such as “la, la, la” so short words were no better recalled than long words. Repetitive task gather up the articulatory process and fills the phonological loop and therefore, takes away the advantage of rehearsal. This is evidence of the articulatory process. Activity in the central executive increases, when an individual performs two tasks simultaneously- This is known as a dual task. An example of this would be such as reading a sentence whilst recalling the final words in each sentence. Evidence in the form of brain damaged patients could be of LH who was involved in a road accident, performed better on spatial tasks rather than those involving visual imagery.