4. the working memory model

what is the WMM

baddely & hitch 1974

• its an explanation of how STM is organised and its functions

• it is concerned with the mental space that is active when we are temporarily storing and manipulating information

• consists of 4 main components, each of which is qualitavely different especially in terms of coding and capacity

WMM definition

a representation of STM suggesting it is a dynamic processor of different types of information using subunits coordinated by a central decision making system

WMM components

• central executive (CE)

• phonological loop (PL)

• visuo-spatial sketchpad (VSS)

• episodic buffer (EB)

central executive

• coordinates the activities of the three subsystems

• it monitors incoming data, focuses and divides our limited attention and allocates subsystems to tasks

• limited processing capacity and does not store information

phonological loop

• processes auditory information (coding acoustically) and preserves the order in which the information arrives

• its subdivided into:

  1. the phonological store - stores the words you hear

  2. the articulatory process - allows maintenance rehearsal (repearing sounds or words in a loop to keep them in working memory while they are needed). capacity of this loop is believed to be two seconds worth of what you can say

visuo-spatial sketchpad

• stores visual and/or spatial information when required

• limited capacity, which according to baddeley is about three or four objects

• logie subdivided it into

  1. the visual cache - stores visual data

  2. the inner scribe - records the arrangement of objects in the visual field

episodic buffer

added to model by baddeley 2000

• temporary store for information, integrating the visual, spatial and verbal information processed by other stores and maintaining a sense of time sequencing - basically recording events (episodes) that are happening

• can be seen as the storage component of the CE

• limited capacity of about four chunks

• links working memory to LTM and wider cognitive processes such as perception

evaluation

1. dual task performance

2. clinical evidence (& counterpoint)

3. nature of central executive

4. lacks ecological validity

dual task performance

• dual task studies support the visuo-spatial sketchpad as a separate system

• baddeley et al found participants struggled when performing two visual tasks but not when combining a visual and a verbal task, suggesting visual and verbal info use separate systems, whereas two visual tasks compete for the same subsystem

• strengthens the WMM by showing disctinct processing for visual (VSS) and verbal (PL) info

clinical evidence

• case studies support the existence of separate memory stores

• shallice & warrington studied KF, who has poor STM ability for auditory information but had good recall for visual information after a brain injury - his PL was damaged but his VSS was intact, indicating separate stores

• supports the WMM by showing distinct auditory and visual memory stores

counterpoint

• unclear if KF’s impairments were due only to his brain injury

• his injury resulted from a motorcycle accident, which may have affected cognitive functions beyond memory - the trauma itself may have influenced his cognitive performance making it hard to isolate memory effects

• challenged the relaibility of clinical studies in proving distinct memory systems

nature of central executive

• the CE is not well defined

• baddeley 2003 admitted it is the least understood component of the WMM and suggested it may be more than just “attention” - some psychologists believe the CE consists of multiple subcomponents rather than a single function

• weakens the WMM by highlighting the unclear nature of its most crucial component

lacks ecological validity

• dual task studies support WMM but may lack ecological validity

• studies show tasks using the same subsystem are harder than those with different subsystems, however these tasks are artificial and not reflective of real life memory use

• while dual task studies provide strong evidence for separate systems, they may not generalise to everyday situations - supports WMM in principle but questions its real world applicability