Research School Network: Dual Coding- what, why and how.

Dual Coding- what, why and how.

by Norwich Research School
on the

What is it?
Many may consider it to be a new term to describe an old technique, but dual coding is the combination of visuals and words in the classroom to aid learning. It has garnered attention since the Learning Scientists named it one of their six strategies for effective learning. It is argued that a combination of auditory and visual aids increases both retention and recall amongst students.

What does it involve? 
Primarily, Dual Coding involves thinking about the delivery of material in your lesson: if you provide students with an image and a text, it is possible this will lead to cognitive overload for students (more on that below). Providing an image and verbally explaining the material encourages more of the material to be retained as students have less to process at one time. As Oliver Caviglioli explained at ResearchEd 2017, words can be complicated. If they are spoken and there is nothing to accompany them, then they are invisible,” transient” and aren’t retained. In addition, words can over complicate: sometimes teachers are guilty of using 100 words to explain a concept or idea, when one well found/​designed image will do the job just as well. Perhaps controversially given he was in a room of teachers at the time, Caviglioli posed the idea that perhaps we are making things too complex for students through our language and subject knowledge. Dual Coding is about simplifying complex ideas where it can be done so.

Whilst it sounds straightforward – who doesn’t like a nice picture on their PowerPoints?! – like a lot of educational research, it can seem a bit complex than it first appears when you examine the science behind it. The key is having the appropriate visual’ whether its text or a picture: A Google image search and picking the first picture won’t cut it here. You may even decide to create your own image!

What’s the science behind it?
Allan Paivio hypothesised as early as 1971 that verbal and visual information are processed differently and using distinct channels in the brain, creating separate representations and triggers. This idea was built upon by John Sweller in the 1980s who developed Cognitive Load Theory – an idea currently making the educational rounds after Dylan William called it the single most important thing for teachers to know’ (William 2017). Cognitive load theory is based on a number of accepted theories about how the brain process and store information. Its link to Dual Coding is the widely accepted idea that an average person can only hold about four chunks of information in their working memory at one time (Cowan 2001). If working memory is overloaded by texts, images and spoken word simultaneously, there is a greater risk that the content being taught will not be understood by the learner, will not be effectively encoded in long-term memory and that learning will be slowed down (Martin 2016).

This problem can be addressed in two separate ways – the split attention effect’ and the modality effect.’ Put simply the split attention effect refers to the difficulty experienced by learners when they need to process two or more sources of information simultaneously in order to understand the material e.g. when a diagram is used to explain a concept but it cannot be understood without referring to a separate piece of explanatory text. Processing and synthesising two images places a high cognitive load on the working memory, making it less like the information will be transferred into long term memory (Cerpa, Chandler & Sweller 1996). To aid this, the modality effect suggests it is possible to decrease cognitive load by using both auditory and visual channels to increase the capacity of the working memory (Penney 1989). As these are two separate channels they can be accessed in different ways but simultaneously, increasing the likelihood of information being passed into the long term memory. Dual coding can be used to provide this auditory and visual stimulus.

For an overview of Cognitive Load Theory and the science behind it see Cognitive Load Theory: Research that teachers really need to understand” August 2017

What does it look like in the classroom?
Now that dual coding sounds complicated because of the cognitive science, here’s the good news – it’s not as complicated as it can appear. The key things to remember and implement in your classroom are:

  • Choose your visual’ element carefully. If explaining a key concept, you want to keep it as simple as possible. The image should be concise and to the point – a photograph can provide too much background detail that can obscure the main point you are trying to make (visual noise). Students may focus on the bits you don’t want them too!
  • Same applies for videos – whilst generally good at providing the visual and auditory aspect, moving images can overstimulate by providing too much for the students to focus on and so they can lose focus on the key points.
  • If you need to, draw the visual’ image yourself – the key is to focus on the most important details, removing irrelevant noise.’ Drawing it yourself can gift you with the opportunity to challenge misconceptions too! (See bluebunson blog below for examples) You don’t need to be Cezanne – just look at the accompanying handout to see my attempt at dual coding to see what I mean!
  • When explaining a diagram or image, do it verbally rather than through an accompanying text. Processing both visual elements puts a heavy load on working memory for students.
  • Don’t talk through text on the board that accompanies an image they are copying/​writing/​reading: it can overload the memory and prevent retention:
vicki dc 1

Image taken from 3starlearningexperiences

For further examples of how people have used it in the classroom, see below links:

Why should I try it?
Ever had a lesson where you believe you have succinctly explained a key topic, concept or idea, to check for understanding and realise none of them have got it? I have – it happened last week. On Wednesday I was trying to explain how Germany transitioned from a monarchy to a republic after WW1. I realised in Friday’s lesson by the look on their faces I was making it too complicated for many of my students with my language and own subject knowledge. Over the weekend I drew a concept map with the key points on they needed to know and we tackled it again on Monday. I checked their understanding again in today’s lesson by just having similar images on the board and they could recall the process from monarchy to republic perfectly. My visual imagery had given them a second prompt and so the information had been retained. If I had done it last week I would have saved myself a painful and exasperating 2 lessons. If you know there are sticking points that can be tackled in a similar way in your lesson and it could save precious curriculum time, why wouldn’t you?! On a simpler note, just trialling not talking over PowerPoints and varying auditory and visual will have a real impact and see greater retention.

vicki dc2

Cerpa, N, Chandler, P & Sweller, J 1996, Some conditions under which integrated computer based training software can facilitate learning’, Journal of Educational Computing Research, vol. 15, no. 4, pp. 345 – 367.

Chandler, P & Sweller, J 1991, Cognitive load theory and the format of instruction’, Cognition and Instruction, vol. 8, no. 4, pp. 293 – 332.

Cowan, N 2001, The magical number 4 in short-term memory: A reconsideration of mental storage capacity’, Behavioural and Brain Sciences, vol. 24, no. 1, pp. 87 – 114.

Martin, A 2016, Using Load Reduction Instruction (LRI) to boost motivation and engagement, British Psychological Society, Leicester UK.

Penney, C 1989, Modality effects and the structure of short-term verbal memory’, Memory and Cognition, vol. 17, no. 4, pp. 389 – 422.

Wiliam, D 2017, I’ve come to the conclusion Sweller’s Cognitive Load Theory is the single most important thing for teachers to know <>, tweet, viewed 24 March 2017, Dylan William Tweet.

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