Dual Coding in a Nutshell

“The drawing shows me at one glance what might be spread over ten pages in a book.” Turgenev, 1861

What is it?

Dual coding is learning using different sensory pathways to transfer information into the working memory. We then encode the information into our long term memory and the more ways in which we learn, the more durable our memory will be.

For example, if I asked you to share all you know about onions you would be relying on a range of sensory information: the sight, the smell, the taste, the feel, all of which are linked to your onion schema in your long term memory. You may even trigger memories of seeing and hearing a cantankerous ogre conversing with a talking donkey about how the layers of an onion are analogous to the complexities of ogre-kind… All these different inputs lead to a deep and durable understanding of the humble onion.

In most classrooms we deal with verbal and visual information the majority of the time so those are the inputs we tend to focus on. @olicav’s wonderful infographic illustrates superbly what we, as teachers, need to know.

However, all is not equal in the world of dual coding. Visual information is, if well constructed, easier to process than verbal information such as text and therefore carries a lower cognitive load. We can absorb several aspects of an image at the same time (synchronously) whereas verbal information must be taken in sequentially if it is to be coherent and understandable.

Despite our eyes being able to admit both visual and verbal information, into our working memory, they cannot do this simultaneously. This is an important point to remember.

Approaches to Dual Coding in the Classroom

Number 1

One method is to present images and text next to each other (like in a textbook). This is more effective than the text alone.

Pros

The written words remain visible unlike spoken words, which are ephemeral, so learners don’t have to hold them in their mind. This will reduce cognitive load as the transient information effect is avoided.

A carefully constructed explanation can be delivered without mistakes.

Cons

The eyes are the sensory means for acquiring both modes of information. Learners will incur a switching penalty as they glance from the image to the text meaning an increase in cognitive load due to the split attention effect.

The visual and verbal information cannot be processed simultaneously so it takes more time to study the material.

If pupils are reading the information independently, they may make mistakes if there is novel vocabulary where the pronunciation hasn’t been modelled.

If the teacher reads the information to the pupils, then they could look at the image but this then renders the written words redundant. Pupils may be more likely to follow the text with their eyes instead of looking at the image whilst listening.

Number 2

Another approach would be to have only the image visible and provide the verbal information by speaking. This frees up pupils’ eyes to focus on the diagram and their ears can gather up the verbal.

Pros

The visual and verbal information can be processed simultaneously, so is more efficient, and it reduces the cognitive load imposed by switching focus between image and text. (modality effect)

Any novel vocabulary can be modelled and practised chorally to reduce the chance of mistakes.

The carefully planned explanation can still be delivered: the teacher could have it in front of them to read if they wished. You can also add a little more flair and relevant hinterland without creating an overwhelming amount of text.

Gestures can be used to direct attention to the relevant parts of the diagram as the sequential verbal information is delivered.

Cons

The spoken words are transient so pupils cannot re-check information as easily without interrupting the explanation.

The simultaneous processing of the visual and verbal information does have more cognitive load than each one individually but less so than the two combined. However, you may need to consider how much information to deliver in one go pretty carefully. Knowing your learners will aid this judgement immensely.

Number 3

Live drawing on either the board or under a visualiser is a fantastic way to facilitate dual coding for your pupils. Your gradually emerging visual information is complemented by your rich discourse as you build pupils understanding of the concept you are delivering.

Adam Boxer’s blog from December 2019 delves more deeply into this and a blog of my own from March 2019 offers another concrete example.

Yes, I know, it ends up looking like I drew a b… but it’s not. Look, I labelled it like it’s the Earth!

Pros

The main benefits mirror those of presenting the information as described above but with live drawing you can gradually build up information more easily and responsively: you can add improvised tweaks if needed to help ensure understanding.

The diagram should be simple, meaning it won’t have any extraneous features, and pupils should be able to easily draw it into their books.

You can add some humour and humanity based on the quality of your drawings… (see above!)

Cons

Sometimes the effects which can be achieved through animations are more beneficial to understanding, than seeing a still image. This can be achieved through live drawing but you’ll need a rubber or things get messy!

The only other real barrier I have found when live drawing is the limitations imposed by my own penmanship and quality of handwriting (as seen above!) but these, as with all things, improve with practice!

Make Your Choice

So, however you choose to enable your learners to benefit from dual coding, do so wisely and with care. Fairly simple concepts might be best delivered using method number one as pupils can more easily understand whereas more complex ideas may require being taught in smaller steps and live drawing may be the appropriate choice.

As always, I can be found on the twitter as @MrTSci409

Thanks to Oliver Caviglioli, Adam Boxer and Pritesh Raichura for the inspiration!

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