Working memory model (Baddeley and Hitch, 1974)

Introduction to Working Memory

In the previous chapter, we looked at the Multi-store Model (MSM) by Atkinson and Shiffrin, which suggested that short-term memory is just one single "bucket" where we keep information. However, Baddeley and Hitch (1974) felt this was too simple. They believed that short-term memory isn't just a static store, but an active processor—like a mental workspace where we manipulate information.

Imagine you are trying to follow a map while someone is giving you verbal directions. You are using your eyes and your ears at the same time. Baddeley and Hitch developed the Working Memory Model (WMM) to explain how we manage these different types of information simultaneously.

Quick Review: Remember, this model only focuses on Short-Term Memory (STM). It does not try to explain how Long-Term Memory works in detail.

The Four Components of Working Memory

Baddeley and Hitch proposed that working memory is made up of a "boss" and several "assistants" who handle specific types of tasks.

1. The Central Executive (The Boss)

The Central Executive is the most important part of the model. Think of it as the manager of an office. Its job is to:

• Monitor incoming data and make decisions.
• Allocate tasks to the other "slave systems" (the assistants).
• Focus, divide, and switch our attention.

Important Note: The Central Executive has a very limited capacity. It cannot do too many things at once, and it does not store any information itself; it just directs it.

2. The Phonological Loop (The Inner Ear & Voice)

This component deals with auditory information (sounds) and keeps the order of words in check. It is divided into two sub-parts:

• The Phonological Store (The Inner Ear): This stores the words you hear for a few seconds. If you don't repeat them, they fade away.
• The Articulatory Process (The Inner Voice): This allows for maintenance rehearsal. It’s that little voice in your head that repeats a phone number over and over so you don't forget it. It has a capacity of about 2 seconds worth of speech.

3. The Visuo-spatial Sketchpad (The Inner Eye)

The Visuo-spatial Sketchpad handles visual information (what things look like) and spatial information (where things are). If someone asks you how many windows are in your house, you probably "visualize" your house and walk through it in your mind. That is your Visuo-spatial Sketchpad at work!

Like the others, it has a limited capacity (usually about 3 or 4 objects).

4. The Episodic Buffer (The Glue)

The Episodic Buffer was added to the model later (in 2000) because the original model couldn't explain how the "visual" and "sound" parts of memory talked to each other.
Its jobs are to:

• Integrate information from the other components into a single "episode."
• Link working memory to Long-Term Memory.
• Provide a temporary storage space with a capacity of about 4 "chunks" of information.

Key Takeaway: The WMM suggests that our short-term memory is divided into specialized systems. This explains why we can do two tasks at once if they use different systems (e.g., listening to music while drawing), but we struggle if they use the same system (e.g., trying to read a book while someone is talking to you).

Applying the Model: Dual-Task Performance

A great way to understand this is through Dual-Task studies. Baddeley and Hitch found that if you ask a person to do two visual tasks at the same time, they perform poorly because both tasks are competing for the limited capacity of the Visuo-spatial Sketchpad.

However, if you do one visual task and one verbal task, you can do them both almost perfectly! This is because they are using two separate systems (the Sketchpad and the Phonological Loop) that don't interfere with each other.

Analogy: Think of it like a kitchen. You can use the oven and the microwave at the same time because they are different machines. But you can't bake two different cakes in the same oven at the same temperature at the same time—the "capacity" of the oven is limited!

Evaluating the Working Memory Model

In your exam, you will need to evaluate the credibility, validity, and reliability of this model.

Strengths

• Credibility: There is strong evidence from brain-damaged patients. For example, the case of KF (though mentioned more in general memory studies) showed that he could remember visual info but not verbal info. This supports the idea that there are separate stores for different types of information.
• Objectivity: Much of the research supporting the WMM comes from laboratory experiments. These use highly controlled conditions, making the results reliable (they can be tested again and again to get the same result).
• Application: The model is more "real-world" than the MSM. It helps explain why students find it hard to study with the TV on or why it’s dangerous to use a phone while driving.

Weaknesses

• Subjectivity & Lack of Clarity: The Central Executive is the most important part but the least understood. Some psychologists argue it’s just a "vague" concept and might actually be made of several smaller components.
• Validity: While lab experiments are reliable, they often lack ecological validity. Tasks like "repeating lists of digits" or "tracking a moving light" are not things people usually do in their everyday lives.
• Completeness: The model only explains Short-Term Memory. It doesn't explain how we learn things over a long period or how reconstructive memory (which you will learn about in Bartlett's work) affects our processing.

Common Mistakes to Avoid

• Confusing the sub-systems: Don't mix up the Phonological Loop (sound) with the Visuo-spatial Sketchpad (sight). Use the names as clues: "Phono" means sound (like a phone) and "Visuo" means sight (visual).
• Forgetting the capacity: Always mention that these stores have limited capacity. If you say they can hold "unlimited" info, you will lose marks!
• The "One Store" Trap: Don't describe the WMM as a single box. It is a multi-component system.

Quick Review Quiz

1. Which component is known as the "Boss" of the system? (Answer: Central Executive)

2. Which part of the Phonological Loop acts as the "Inner Voice"? (Answer: Articulatory Process)

3. Why was the Episodic Buffer added to the model? (Answer: To integrate information from different stores and link to Long-Term Memory)

4. What is the capacity of the Phonological Loop in terms of time? (Answer: Approximately 2 seconds)

Don't worry if this seems like a lot to remember! Just keep thinking of the "Office" analogy: The Boss (Central Executive) gives papers to the person at the typewriter (Phonological Loop) and the person at the drawing board (Visuo-spatial Sketchpad). As long as they have their own desks, they can work at the same time!