Functions and characteristics of components of working memory model.

The idea

Baddeley and Hitch's working memory model replaces a single short-term store with active components. The central executive is a limited-capacity attentional controller that allocates resources, switches between tasks and coordinates the phonological loop and visuo-spatial sketchpad. The phonological loop holds verbal-acoustic information briefly; its phonological store decays in about two seconds unless rehearsal refreshes it. The visuo-spatial sketchpad holds visual and spatial information, such as a mental image of a route. The episodic buffer integrates information from the loop, sketchpad and long-term memory into a single multi-modal episode. Each component has limited capacity and duration, and dual-task studies show interference when two tasks use the same component.

What earns the marks

• The central executive is a limited-capacity attentional controller that allocates resources and coordinates the phonological loop and visuo-spatial sketchpad.
• The phonological loop holds verbal-acoustic information briefly and relies on rehearsal to refresh decaying traces.
• The visuo-spatial sketchpad holds visual and spatial information, such as mental images and locations.
• The episodic buffer integrates information from the loop, sketchpad and long-term memory into a multi-modal episode.
• Each component has limited capacity and duration, and dual-task interference occurs when two tasks use the same component.

Common mistakes and how to put them right

• Treating working memory as one single short-term store.

  Put it right: It is a multi-component system with separate limited-capacity stores.

• Assuming the central executive stores information.

  Put it right: It is an attentional controller that allocates resources and coordinates the other components.

• Believing the phonological loop holds visual images.

  Put it right: It holds verbal-acoustic information, while the visuo-spatial sketchpad handles visual and spatial information.

• Ignoring the episodic buffer.

  Put it right: It integrates information from the loop, sketchpad and long-term memory into a multi-modal episode.

Exam tips

• Match each component to its function and capacity limit before choosing an option.
• Use dual-task interference to distinguish components: two verbal tasks compete for the phonological loop, while a verbal and a spatial task can run together.
• Check whether an option describes storage or control; the central executive controls rather than stores.