THE WORKING MEMORY MODEL

• Baddeley & Hitch (1974) questioned the existence of a single STM store, arguing STM more complex than just being a temporary store for transferring information to LTM.
• They see STM as an active store, holding several pieces of info while they're being worked on.  It's a temporary storage system used to help you do more complicated cognitive tasks.
• Baddeley believes that we draw upon the resources in our LTM and SM and bring it into the present to use in conjunction with the new information in the STM, from where the recall of memory takes place.
• Atkinson & Shiffrin would not dispute this as they believed information had to be retrieved from the LTM to be actively used by the STM.
• Baddeley's model is a working memory because all parts work together, in parallel, to create conscious thought and action.
• According to Baddeley, thinking and remembering are inextricably linked.
• Their model doesn't concern LTM.
• Cohen (1990) described working memory as "the focus of consciousness - it holds information consciously about now".
• WMM should NOT be seen as a replacement for the MSM, more as an explanation based upon the MSM.

• To replace the single STM store of the MSM, Baddeley & Hitch proposed a multi-component working memory of initially 3 components:
• Central Executive (CE) - the head of the model which oversees two slave systems: the Visuo-Spatial Sketchpad (VSS) and the Phonological Loop (PL).
• A 4th component and slave system, the Episodic Buffer (EB), was added in 2000 to address shortcomings of the model.
• These slave systems feed information to, and retrieve information from, long term knowledge systems.
• The WMM is a good example of a paradigm shift.  Up until 1950's the study of memory was based on theories of learning with studies carried out on rats.  This collapsed very quickly and the cognitive approach took hold.  
• The term cognitive pyschology was first adopted by Ulric Neisser - it sees the human being as an information processing channel of limited capacity.
• When Baddeley started work on what was to become the WMM, STM research had become unpopular and messy.  All work had been approximated to the MSM.

• Crucial part of working memory.
• Origins for this come from Norman & Shallice's SAS (supervisory attential system) which they  argued had the job of stepping in when routine systems fail or need support.  They were interested in slips of action e.g. Cherboyl, air disasters and frontal lobe attention deficits.
• Baddeley adopted the SAS as his CE.
• Acts as a filter to determine which information, recieved by the sense organs, is and isn't attended to.
• Processes information in all sensory forms, directs information to the slave systems and collects responses.
• It decides which of the slave systems should be given priority. 
• It's limited capacity and can only effectively cope with one strand of information at a time. This is supported by a study conducted by Baddeley (1996) in which participants found it difficult to generate lists of random numbers whilse simulataneously switching between pressing numbers and letters on a keyboard, suggesting the two tasks were competing for CE resources.  
• Baddeley admits that one of the problems was how powerful this CE should be.  Should it remember (store) AND control?  For a while it focused only on control - HUGE JOB!  
• It's a homunculus - SEE CARD ON EVALUATIO OF WMM.

• CE selectively attends to particular types of information, attaining a balance between tasks when attention needs to be divided between them e.g. talking while driving.
• It permits us to switch attention between different inputs of information.
• It also handles cognitive processes such as mental arithmetic.
• D'Esposito et al. (1995) found using fMRI scans that the prefrontal cortex was activated when verbal and spatial tasks were performed simultaneously but not when performed seperately, suggesting the brain area to be associated with the workings of CE.
• Little is known about the CE.  It isn't clear how it works or what it does.  The vagueness means it can be used to explain almost any experimental results e.g. if two tasks cannot be performed together, then the two processing components are seen as conflicting or it is argued that the task exceeded the CE's capacity BUT if two tasks can be done simulataneously it's argued they don't exceed the available resources, in essence a circular argument (it continually proves itself)!
• The CE is probably better understood as a component controlling the focus of attention, rather than a memory store.  Unlike the PL and VSS which are specialised memory stores.

• Deals with auditory information (sensory info in the form of sound) and the order of the information i.e. whether words occurred before or after each other.
• The PL is similar to the rehearsal system of the MSM with a limited capacity determined by the amount of information that can be spoken out loud in about 2 secs.
• Baddeley (1986) divided the PL into two sub-parts:

1. Primary Accoustic Store (PAS)

2. Articulatory Process (AP)

• The PAS, aka inner ear, stores words recently heard e.g. allows us to hold a melody we've just heard or the sound of the sirens on a fire engine that has just passed by.
• The AP, aka inner voice, keeps information in the PL through sub-vocal repetition of information and is linked to speech production e.g. when we say a phone number over and over again to hold it in our STM between reading the number and dialling it.
• Trojani & Grossi (1995) reported a case study of SC who had brain damage affecting the functioning of his PL but not his VSS, suggesting the PL to be a separate system.
• Baddeley (1975) reported on the. word length effect, where participants recalled more short words in serial order than longer words, supporting the idea that the capacity of the PL is set by how long it takes to say words, rather than the actual number of words.

• It's thus been show that memory span (how much we can hold in our STM at any one time) is linked to speech and chances are that if you're a slow speaker you'll have a relatively small memory span, and if you speak quickly, a longer memory span.
• PET scans show that different brain areas are activated when doing visual and verbal tasks which suggests that the PL and the VSS are seperate systems, reflected in the biology of the brain.
• The PL is strongly associated with the evolution of human vocal language, with the development of the slave system seen as producing a significant increase in the short term ability to remember vocalisations.  This then helped the learning of more complex language abilities, such as grammar and expressing meaning.
• Studies have shown strong indications ADHD appears to be part of a deficit with the PL.
• Baddeley discovered that children who had problems learning nonsense syllables and non-words that were longer at the age of 4 - this is now a standard test used in the diagnosis of dyslexia - predicted how much their vocabulary would improve by the age of 6.

• The VSS, or inner eye, handles non-phonological information and is a temporary store for visual and spatial items and the relationships between them (what items are and where they're located).
• Helps individuals to navigate around and interact with their physical environment, with information being coded and rehearsed through the use of mental pictures.
• Logie (1995) suggested sub-dividing the store into:

1. The Visual Cache (VC) - stores visual material about form and colour

2. The Inner Scribe (IS) - handles spatial relationships and rehearses and transfers information in the VC to the CE.

• Baddeley says it's possible that rehearsal in PL may be atypical.  There are other types of rehearsal with different types of memory and the mode of rehearsal for visual images is less clear than for verbal information.
• Gathercole & Baddeley (1993) found participants had difficulty simultaneously tracking a moving point of light AND describing the angles on a hollow letter F, because both tasks involved using the VSS. Other participants had little difficulty in tracking a light (uses the VSS) and performing a simultaneous verbal task (uses the PL), suggests the two slave systems are separate from one another. 

• Klauer & Zhao (2004) reported more interference between two visual tasks than between a visual and spatial task, implying the existence of a separate visual cache and inner scribe.
• Kosslyn (1973) drew out pictures of objects and asked people to view them for a few seconds.  Pictures had a number of component parts, all stategically placed so that Kosslyn could ask about their location on the diagram. He took the pictures away and asked participants to say whether a particular object was present on the picture and where it was in reation to the left of the image.  In order to do this, they had to scan the image in their mind. He found that the further away the image was from the left hand side, the longer it took to say whether or not the item was there.
• PET scans not only show the VSS and PL to be in separate parts of the brain, they also show brain activation in the left hemisphere with visual tasks and activation in the right hemisphere with spatial information, which further supports the idea of dividing the VSS into a seperate VC and IS.
• Studies of the VSS and PL often feature dual task tehcniques, where participants have to perform two simultaneous activies.  Howevere, the actual tasks performed are often not ones encountered much in everyday life and scuh studies can therefore, be accused of being artificial and lacking in mundance realism.
• Lots of research in cognitive pyschology but much avoiding people experiencing images - Baddeley says this is consider by behaviourists to be quite improper!

• Baddeley and his team asked people to generate images and rate how vivid they were e.g. Maggie Thatcher on the phone and then try and interfere with those images by getting them to carry out another task simultaenously such as tapping keys on a pad in a certain order.
• They found that if the person was focusing on an image they'd just seen or conjoured up, the image was interefered with (became less vivid to the person) but if they were recalling LTM there was much LESS interference.
• This is relveant because images and freaming and holding images is quite important.
• Some evidence that flashbacks, people suffering with PTSD, can be interefered with.
• The same technique may also help with other images e.g. images that are asosciated with desires for drugs, drink etc.

• A third slave system, added in 2000, as the model needed a general store to operate properly.  Followed Baddeley's observations that many patients with amnesia, who presumably have no ability to encode new information in LTM, nevertheless have good STM recall, recalling much more information that could be help in the PL and VSS on their own.
• It works alongside the PL and VSS and holds visual or verbal information there temporarily.  It is a link between all the major components of working memory and also draws information from the LTM.  
• It also chunks information or episodes, in a similar concept to the MSM.
• Baddeley maintains it is crucial in conscious awareness and it also allows for time-sequencing, as in the telling of a story.
• It's a buffer in that it holds information temporarily, combining visual and verbal information from the PL and VSS.  It's episodic in that it combines that information into chunks and episodes.
• It was a popular addition to the WMM because it allowed the European topdown approach and the more bottomup Northern American approach to memory to come together in a way that makes sense.

• Baddeley himself accepts that there is a danger that it's a concept that's untestable and that means it doesn't necessarily advance the field.
• Prabhakran et al (2000) used fMRI scans to find greater right-frontal brain activation for cmobined verbal and spatial info, but greater posterior activation for non-combined information, providing biological evidence of an EB that allows temporary storage of integrated information.
• Alkhalifa (2009) reported on a patient with severely impaired LTM who demonstrated SM capacity of up to 25 prose items, far exceeding the capacity of both the PL and VSS. Supports existence of an EB which holds items in WM until they are recalled.

• WMM suggests practical applications especially for children with ADHD relating to impairments of working memory.
• Alloway (2006) recommends several methods to help children focus on the task at hand:

- use brief, simple instructions so they don't forget what they're doing.

- break instructions down into individual steps.

- frequently repeat instructions.

- ask the child to periodically repeat instructions.

Klingberg et al. (2002) report that computerised WM training, using systematic excercises to produce cognitive gains, is beneficial to those with poor WM.

• The WMM, some argue, is the origin of SELECTIVE INTERFERENCE - using secondary tasks to block or impair processing in particular areas of the brain.
• This method was not commonly used before Baddeley.
• Dual Task Interference is the hallmark of Baddeley's approach to WMM e.g. the 0 back (low load) - 2 back (high load) framework can be used on visual and verbal tasks.  E.g. showing a person an image and asking them to name it, then asking them to name the previous image (1 back), then asking them to name what they saw two images previously (2 back).  Likewise giving the answer to a question they were asked 0, 1 or 2 questions ago.
• Baddeley says you need to understand the system in order to known how to block it!
• TMS v Dual Task Intereference - TMS (transcranial magnetic stimulation) is a way of block brain activity in certain areas of the brain.  Place a magentic coil over head and zap to disable area of brain.  Baddeley argues that TMS is asking the questions WHERE does this happen?  Therefore well placed for anaswering anatomical questions, whilst Dual Task Interference is not as it's asking WHAT is involved and, Baddeley argues, is therefore more flexible.

• Neuroimaging:  Expectation is that brainscanning would be helpful in memory research but on the whole, thus far, it's not proved very informative, according to Baddeley.  He argues that tasks used in WMM are complex and involve a number of areas, so localization is too simple a way of testing the memory system. Also, neuroimagin is expensive, so you need to publish quickly, and therefore research isn't deep, is difficult to replicate unless you have access to expensive equipment and therefore doesn't provide sufficient answers.  Data is highly complex.
• Individual Differences: very obvious when dealing with WMM that some people can remember and manipulate much more information than others.  One study showed that performance in WMM can predict general intelligence performance.

• Baddeley is becoming more convinced that consciousness is related to WM.
• The EB provides a hypothesis - it allows information to be bound together from many sources, it's within a system that can stand above it and reflect it.
• Think of consciousness as a biological function.
• Been known for at least 100 years that people differe markedly as to whether they think they've got strong imagery in their mind or not.  If you look at performance on tests with people who think they've got strong imagery and people who think they don't there's no difference between them, with a possible slight better performance from those who don't!
• So is everyone having the same experience but reporting it differently?  
• A report suggested this might not be the case.  Those who said they had vivid visual imagery showed that these areas of the brain that deal with imagery were indeed more active than those who said they lacked vivid visual imagery.  
• Doesn't mean to say the memory ISN'T based in visual images but the way in which it's displayed is different in some people.

• Over the last 40 years new ideas and thinking have forced the revision of the model e.g. introduction of the EB; new research into how LTM and WM are linked; the identification of procedural working memory (how we remember instructions or sequences in order to perform new tasks); exciting future into WM and emotion, self-control and will.
• The concept of the CE allows us to unify other cognitive processes, not just memory and allows us to see how perception, thought processes and language are all linked.  However critics argue it is vague; not clear how it works or what it really does.  Baddeley accepts this, he calls it his homunculus - part of a model that solves important problems but isn't explained further - he says he is happy for to use homunculi as long as they are retired down the road through more research.
• WM is a flexible construct with a greater emphasis on the "here and now".
• WM is active and constantly changing.
• Strong focus on auditory, phonological and visual has brought about an understanding of how some children find it difficult to learn to read, have dyslexia and it may have strong associations with types of ADHD which are the result of deficits in the PL.
• WM provides a cmore complete answer for thos suffering from brain damage where the effects do not fit the usual expectations of the MSM model.
• Does not tell us much about LTM, although with the addition of the EB we are beginning to see how LTM and STM are linked.

• WMM is supported by brain activity in known language and visual areas of the brain, showing that many different parts of the brain are involved in remembering and supporting an integrative approach to memory.