Baddeley and Hitch defined working memory as a system that temporarily holds and manipulates information. This lesson will explore working memory and its subsystems, including the recent addition of the episodic buffer.
Working Memory Model
Have you ever repeated a phone number in your mind long enough to write it down, or recalled an image of your home’s layout while shopping for furniture? It may seem simple, but it’s actually a complex process. You’ve most likely heard of the distinction between ‘short-term’ vs. ‘long-term’ memory. In the late 1960s, Richard Atkinson and Richard Shiffrin used these terms to describe the different parts of our memory. The short-term component was thought to be a temporary storage space that could hold a small amount of information until it was forgotten or transferred to long-term storage. In addition, long-term storage only occurred if the information was rehearsed in the mind.
Other contemporary researchers found this model to be limited, particularly in its treatment of the short-term component of memory. In 1974, Alan Baddeley and Graham Hitch created a new model that expanded on this component significantly. Instead of a single short-term memory space, Baddeley and Hitch proposed a more complex ‘working memory,’ a system that temporarily holds and manipulates various kinds of information in specialized ways. Working memory consists of several components, called the central executive, the phonological loop, the visuospatial sketchpad, and the episodic buffer, which was added to the model in 2000. Let’s discuss each of these components.
Like its name suggests, the central executive is in charge of the whole working memory system. It is considered the ‘boss’ that coordinates and delegates work to its subsystems, like the phonological loop and the visuospatial sketchpad. These are also called the slave systems. The central executive also plays a large role in controlling attentional resources. For example, imagine you are driving down a busy street while having an in-depth conversation with the passenger in your car. You notice that the car ahead of you is swerving and the driver appears to be intoxicated. You will most likely abandon your conversation and direct all or most of your attention toward avoiding the car. It is the central executive that decides which of these two things deserves your concentration.
Imagine the central executive as the boss of a company. The boss receives information from her assistants (the slave systems) and draws on the information she already has (long-term memory) to decide which strategies are best to deal with a problem. She can only handle a limited amount of work on her own, so she calls on her assistants for help. Now we will discuss these assistants, or slave systems, in more detail.
The phonological loop handles acoustic information, like speech and other sounds. It is further divided into two parts: the phonological store and the articulatory control process. The phonological store holds onto spoken words (and written words that are converted into speech) for a couple of seconds. The articulatory control process occurs when we mentally rehearse something using our ‘inner voice.’ For example, when someone tells you a phone number, the numbers enter the phonological store. Then you’d use the articulatory control process to repeat it to yourself until you can either write it down or commit it to long-term memory.
As you’d guess from the name, the visuospatial sketchpad handles visual and spatial information that helps you navigate the environment around you. This helps you to remember the visual layout of our house, office, and the town you live in. It also acts as a display to show you visual images that are stored in your long-term memory. If you were asked to describe the furniture in your office, the visuospatial sketchpad will display an image of your office in your mind.
Several researchers, including Baddeley, found that the working memory model was missing something – a component that can integrate and bind various types of information together. In 2000, Baddeley proposed a fourth component, called the episodic buffer, a system of limited storage that integrates information from different sources. It draws information from the senses, long-term memory, and the slave systems, and stores it in an integrated fashion to help us perceive the world coherently.
While the central executive also integrates information, Baddeley found it to be limited in the complexity of things it can hold. In our company example, the boss has decided to hire an assistant who can bring the various departments together for a project. Like the other slave systems, the episodic buffer is controlled by the central executive, which can retrieve information from it through reflection, conscious thought, and drawing on long-term memory. As you can see, without her trusty assistants, the boss would have difficulty juggling everything at once.
Working memory is a system that temporarily holds and manipulates information. It has four components: the central executive handles attention and delegates work to the slave systems. The phonological loop holds auditory information through the phonological store and the articulatory control process. The visuospatial sketchpad displays visual information, and the episodic buffer integrates everything.