working memory model

The working memory model was created by Baddeley and Hitch as a new approach to understanding how short-term memory works, while overcoming some of the weaknesses of the MSM — particular, it accounts for the evidence that STM is not a single store.

• Instead, STM is seen as an ‘active store’, holding several pieces of information while they are being worked on.

• The multi-component model initially consisted of 3 components: central executive, visuo-spatial sketchpad and the phonological loop, with the episodic buffer being added later in 2000.

central executive

Information:

• Oversees and coordinates components of STM

• Filter to determine which info received by sense organs is and isn’t attend to

• Directs info to the model’s slave systems

• It’s limited in capacity and can only affectively cope with one strand of info at a time

• Main component involved in working memory tasks that require a constant switch between visual and acoustic e.g problem solving

Research:

• D’esposito et al — found using fMRI scans that prefrontal cortex activated when verbal and spatial tasks were performed simultaneously but not separately.

• This suggests that the brain has another controlling section activated for tasks requiring two skills.

visuo-spatial sketchpad

Information:

• ‘Inner eye’, handles non-phonological info and is a temporary store for visual + spatial items and the relationship between them

• Visual cache: stores visual material about form and colour

• Inner scribe: handles spatial relationship and rehearses + transfers info in VC to CE

Research:

• Gathercole and Baddeley — ppts had difficulty simultaneously tracking a moving point of light and describing the angles on a hollow letter F, because both tasks involved using VSS

• Other ppts had little difficulty tracking light and performing a simultaneous verbal task, as they involved VSS and PL, indicating the VSS to be a separate slave system

phonological loop

Information:

• Deals with auditory info

• Has a duration of 2 secs

• As it’s mainly acoustic store, confusion can occur at similar sounding words

• PL divided into 2 parts:

  • Primary acoustic store — ‘inner ear’, stores words recently heard

  • Articulatory process — ‘inner voice’, keeps info in the PL

• Sub vocal repetition of the info and linked to speech production

Research:

• Baddeley et al — demonstrated word length effect:

  • Asking ppts to remember long and short words in a list

  • They could hold less long words in PL due to its short duration because each word occupied so much more memory space

• This supports the idea that the duration of the PL is limited to 2 seconds

episodic buffer

Information:

• Used to explain info how can be retrieved from LTM and brought back to STM to focus on (CE cannot do this as it only filters live info from the environment)

• Al Khalifa — neuroscientific evidence has found a different area of the brain when asking ppts to bring info from LTM back to STM — suggesting evidence of EB

evaluations of the WMM

• Supporting research: KF case study, suffered brain damage from a motorcycle incident that damaged his short-term memory. Impairment was mainly for verbal info, his memory for visual info was largely unaffected. Therefore shows there are separate STM components for visual and verbal info, supporting the WMM

• Supporting research: Baddeley and Hitch, dual task study where ppts asked to perform 2 tasks (one phonological and one visual) at the same time. They found that because the dual task made use of the CE to direct attention to the slave stores, the 2 tasks could be performed quite well in comparison to 2 verbal or 2 visual tasks simultaneously. Therefore, shows the are separate STM components for visual and verbal info, supporting WMM

• Contradictory evidence: Lieberman criticises the WMM, as the VSS implies that all spatial info was first visual. However, Lieberman points out that blind people can have excellent spatial awareness, even though they haven’t had visual info on the space. Therefore, Lieberman argues VSS should be separated into 2 components for visual and spatial instead of one store.

• Little evidence for how the CE works and what it does: for example, the capacity of the CE has never been measured and in addition, it has been argued to be a component controlling the focus of ‘attention’ rather than a memory store in its own right. This means we are unsure of the CE’s role as a memory store, making model less valid.