Working Memory

Working Memory

1. A memory subsystem that comprises a set of mental structures and processes involved in organising and integrating sensory and other info held in the short-term memory store

2. Working memory is needed for a wide range of cognitive tasks, including reading, maths, reasoning, problem solving and language comprehension

3. Baddeley and Hitch first proposed that the purpose of STM is to hold pieced of info in mind simultaneously so it can be manipulated and used as appropriate (can be likened to a workbench, a place for combining new sensory memory and old long-term memory)

4. Baddeley's Working Memory Model

   • Central Executive
     • Limited capacity processing system resembling attention: Modality free
     • Works as an information integrator and behaviour coordinator, combining info from the visuospatial sketchpad, phonological loop, episodic buffer and LTM
     • Helps you to focus on your goal by suppressing distracting stimuli and enhancing attention to relevant aspects
     • Has a limited capacity to work on tasks simultaneously, cannot work on two competing problems simultaneously
     • If a strategy doesn't work, it devises an alternative, rather than repeatedly using the failing strategy
     • Is thought to be represented predominately in the prefrontal cortex
       • This region is responsible for the ability to select actions and organise behaviour according to preferences
       • Patients with damage to this area exhibit symptoms like goal neglect: reliance on habitual responses even if those responses do not bring you closer to your goal
       • Damage also leads to perseveration: tendency to produce the same response repeatedly, even when the task clearly requires a change in response
   • Phonological Loop
     • Temporary storage system holding verbal info in phonological form
     • Processes a limited number of sounds for a limited period of time
     • Research confirms that people confuse stimuli that sound similar, supporting the notion that material is stored in sound form in the phonological loop
       • Conrad and Hull demonstrated that people recall more items from lists containing stimuli that sound different than from lists containing stimuli that sound different than from lists containing items that sound similar
     • Articulatory Suppression: Repeating a word or syllable aloud repeatedly whilst performing another task
       • Using this you can determine whether your phonological loop is necessary for a given task
     • It is finite and immediate memory of spoken words is affected by word length
     • Brain activation occurs in the left hemisphere's frontal and temporal lobe, also in the left parietal, subvocal rehearsal activates Broca's area and parts of the motor strip
   • Visuospatial Sketchpad
     • Temporary storage system holding spatial and/or visual information
     • Baddeley et al., participants typically report encoding the info visually as a path through the matrix
       • Participants typically report encoding the info visually as a path through the matrix
     • Allows you to gather visual info about objects from complex scenes, allowing development of a coherent representation of the objects and their relative positions
     • Sketchpad is used less than the phonological loop, but we use it to navigate the world
     • Relies predominately on a right hemisphere cortical substrate
       • Visual working memory tasks generate initial activation in the occipital lobes, activation then spreads to the right frontal region which controls spatial working memory
         • This region is closely located to the frontal eye fields, which control the movement of the eyes
       • Shifts in attention linked to the visuospatial stimuli generate fronto-parietal activity
   • Episodic Buffer
     • Works as a temporary store where info from the phonological loop, visuospatial sketchpad and LTM can be gathered and combined
     • Info can be manipulated, allowing you to reinterpret events, solve problems, and plan for the future, by combining knowledge from LTM

5. Tasks

   • If 2 tasks rely on the same component of working memory, they can't be performed together (capacity limited)
   • If 2 tasks rely on different components of working memory, they can be performed simultaneously
   • Found an extremely high correlation between working memory capacity and reasoning ability
   • Central executive task scores correlate highly with verbal fluency, reading comprehension and reasoning ability
     • This suggests that working memory capacity is very similar, if not identical to, general intelligence
   • People with lower working memory capacities are more susceptible to the cocktail party effect, are more easily distracted by peripheral cues
     • Thus the attentional control linked with working memory capacity may help explain differences in intelligence
   • Research suggests that working memory training can enhance fluid intelligence (the ability to reason and solve new problems independently of previously acquired knowledge
   • n-back Task
     • A task involving extremely high working memory demands
     • This test is important because it shows the enhancement of fluid intelligence by cognitive training different from training the test itself

6. Working Memory and Depression

   • Participants completed tests tapping the different components of working memory
     • Phonological Loop Tasks (articulatory suppression)
       • Depressed: 3.4 letter memory span
       • Controls: 5.3 letter memory span
     • Visuospatial Sketchpad Tasks (matrix completion)
       • Depressed: 6.7 items matched
       • Controls: 7.8 items matched
     • Central Executive Tasks (listen to letter series and repeat in reverse order)
       • Depressed: 2.8 letter memory span
       • Controls: 4.9 letter memory span
     • Findings clearly illustrate working memory deficits in people with major depression
       • This is consistent with reports of difficulty concentrating typical of people suffering from depression
       • Poor cognition performance on daily tasks is likely to increase depression levels, leading to a vicious cycle

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