On Thursday I delivered a staff briefing to my colleagues on Dual Coding and the working memory. As always when I am presenting to staff, I am concerned that I am being clear, that the information I am providing is helpful and that it is accurate.
– Many of the images I used in the presentation, including the one above, are the superb work of Oliver Caviglioli
The first point about Dual Coding is that it can help teachers to improve their explanations. In its simplest form it is about improving a verbal explanation by using a well judged image to support it.
In order to understand why dual coding is helpful for teachers and students in the classroom, I want to recap some ideas about how we learn. Here is Dan Willingham’s “simplest possible model of the mind”
We recall that the long term memory is where we store everything we’ve learned, “if nothing has changed in the long term memory then the nothing has been learned“. The environment is our school, our classrooms and our teaching. And the working memory is where one thinks about new things, it’s where students do their thinking about new information that we are teaching them.
Our long term memories are effectively limitless in capacity, it is not the case that if we learn something new, then something else has to fall out. Whereas the working memory is very limited in capacity, with perhaps space for 4 – 6 items at once. For example, most adults will struggle to multiply 14 by 37 in their heads. This not because of its complexity, just that they can’t juggle all the information in their heads at once. It is really just a few simple calculations, but the limited space in our working memories makes it an extremely hard task.
Oliver Caviglioli has this brilliant image for the limited capacity for the working memory. I am dual coding here by giving a written explanation with an image that supports and improves it. I think the limited capacity of the working memory has huge implications for teachers. As Willingham says in his wonderful book people are naturally curious but not naturally good thinkers, and when we can, we tend to avoid using our working memories. It is easier for us to rely on things we’ve always done than to have to think about new ideas; thinking is slow, effortful and difficult. And yet this is what we want students to be doing often every day.
One way to ease the burden of the limited capacity of the working memory is to dual code when we give an explanation in class. Let me give you an example from Geography:
Here you are going to have to imagine me giving the following explanation verbally whilst having this slide projected next to me:
I was clear and precise with my wording on that explanation, but it wasn’t a good one. The reason for this? I had what I was saying written down on the board for you to read along with. Although this is not immediately obvious, reading and listening to the same words makes it harder to take on board the communication.
For this reason, I often give my explanations with a completely clear backdrop, or a blank slide, to encourage students to be completely focused on what I’m saying.
Often I find it hard to get a good image to improve my explanation. In my understanding a good image for dual coding must be fairly simple; photographs can be too detailed. Caviglioli’s are brilliantly simple but convey information very clearly. I don’t think it’s easy to find or develop these images. However, I think it’s something that I can look for over my career – good, strong, effective images to support my explanations.
A better explanation for the above example would be to just have the image on the screen as I gave the verbal explanation. Explanation and image good; explanation and text bad.
Let’s focus in on the working memory to see why that might be the case
– This image is taken from the book What every teacher needs to know about Psychology by Didau and Rose
As an aside, I want to say that I think the best way to alleviate the pressure of the limited capacity of working memory is to ensure students know as much as they can about your subject. For example, if you’re teaching the Second World War in Y9, then a good way to make that as simple as possible for students to learn is to have taught the Treaty of Versailles in Y7 and The Great Depression in Y8. The more students know about your subject, the easier it is for them to know more.
Refocusing on Dual Coding. In the image above, the phonological loop processes verbal explanations and text, and it gets overloaded if both are used at the same time, hence the redundancy effect. The visuospatial sketchpad processes images, therefore if you utilise it along with the phonological loop, both can complement each other in terms of processing the information. That is the dual coding.
Dual coding goes further than just enhancing verbal explanations with visuals, as the next example will demonstrate. Again, this is from Oliver Caviglioli. Try and read the following and answer the questions:
Language is sequential, and is often not the best way to impart information. Particularly with content that involves hierarchies, connections or relationships. Here, Caviglioli presents the same information in a visual way. The answers to the questions in blue now seem trivial
Let me summarise what I’ve said:
Verbal explanation with words: bad. Verbal explanation with a well-judged image: good.
And the limited capacity of the working memory has many implications for teachers, including the importance of Rosenshine’s Principles of Instruction, and Dual Coding, which includes the helpfulness of diagrammatic structures for presenting new information
– Again, these great images are by Oliver Caviglioli