The working memory model

• The Working memory model was proposed by Baddeley and Hitch in 1974.
• The Working model of memory only focuses on the STM.
• The Working model of memory is only concerned with the part of the brain that is active when we are temporarily storing and manipulating information.
• The Working Model of memory consists of 4 component: the central executive, phonological loop, visuo-spatial sketchpad and the episodic buffer.
• Central executive is the supervisory component that has overall control of working memory. It has a limited capacity and processes sensory info.
• The central executive decides what to pay attention to, allocates tasks to slave systems and monitors incoming data.
• Phonological loop is the slave system that focuses on auditory information and preserves the order in which info arrives. 
• The phonological loop is subdivided into the ‘inner ear’ deals with auditory info (what is heard) and the ‘articulatory loop' which keeps words that are heard in the working memory via maintenance rehearsal using the 'inner voice’ to repeat words in our head.
• The visuo-spatial sketchpad is the slave system that stores visual and/or spatial information.
• The visuo-spatial sketch pad is subdivided into the visual cache which stores visual data and the inner scribe which records the arrangement of objects in visual field.
• The visuo-spatial sketch pad has a limited capacity of 3-4 items according to Baddeley (2003).
• The episodic buffer is a temporary store of memory that integrates visual, spatial and verbal info processed by other stores into a single memory, while maintaining a sense of time sequencing.
• The episodic buffer links working memory to LTM.
• Baddeley at al. (1975) investigated what is known as the word length effect, where participants recalled more short words in serial order than longer words. This is because there is a limited space for rehearsal in the articulatory process (around 2 seconds). Baddeley concluded that the capacity of the PL is set by the duration of words and not the number of words.
• KF was used as evidence for the WMM. KF suffered damage to his phonological loop as he had difficulty with sounds due to a motorcycle accident, but his visuo-spatial sketchpad was left intact as he could recall verbal information presented visually. As other parts of his STM were intact, he was able to transfer information to his LTM.
• A weakness of the WMM is that the evidence from brain damaged patients is not reliable and cannot be generalised to the general population. Brain injuries are really unique and traumatic, and this trauma may be what causes the memory to change or perform worse on tasks, not the actual brain injury. 
• A weakness of the WMM is that some psychologists believe that the the definition of the CE is too vague and does not really explain much other than it ‘organises resources’ and ‘focuses attention’. Critics also feel that the idea of one central executive is wrong and that it is likely there are sub-components to the slave driver. This means that the WMM is lacking a comprehensive explanation of STM.
• A strength of the WMM is that there is supporting studies such as Dual-task performance by Baddeley et al. Baddeley et al showed that there was different components of STM as stated in the WMM. Participants struggled to perform the task of tracking a light and describing the letter F, as both tasks required the attention of the visuo-spatial sketchpad. When participants were presented with both a visual and verbal task, they struggled less as the tasks required different slave systems. This supports the idea in the WMM that there are separate slave systems that process different sensory info.
• A limitation of the WMM is that evidence from case studies of patients with brain damage cannot be generalised to the public. This is because they have serious damage to their brain which is rare. This means that their memory functions differently to the general public. Also, brain injuries due to traumatic accidents, could lead to PTSD which could also impair their ability to preform well in the memory tasks as they may be going through something subconsciously which could be seen as a confounding variable. This limits the WMM explanation of STM for the wider population.