Dual Coding: Pair Words With Pictures to Remember More

Try to remember a paragraph about how the heart pumps blood. Now picture a simple diagram with four chambers and arrows. Most people find the picture easier to call up, and easier still when they can also explain it in words. That is the idea behind dual coding: you study an idea in words and in a visual form, and the two support each other.

It is not about decorating your notes or being a visual learner. It is about choosing a picture that shows the structure of the idea, then linking it tightly to the words. Done well, it is one of the most practical ways to make dense material easier to understand and recall.

Paivio developed the theory from the 1960s onward, and later applied it to schooling with James Clark in a paper called Dual coding theory and education. A concrete word like apple is easy to code twice, because you can picture it. An abstract word like justice is harder, so it often gets only a verbal code. That is one reason concrete examples and diagrams help so much with abstract topics: they give the idea something to picture.

Richard Mayer at the University of California, Santa Barbara, built his theory of multimedia learning partly on Paivio's work. In the opening chapter of the Cambridge Handbook of Multimedia Learning, he reports that students who learned from words and pictures together outperformed students who learned from words alone on problem-solving transfer tests in nine out of nine studies, with a median effect size of 1.50. That is a very large effect by education research standards. He calls it the multimedia principle: people learn better from words and pictures than from words alone.

There is an important limit. The 2013 review of study techniques by Dunlosky and colleagues rated imagery for learning text, which means simply asking students to form mental pictures while they read, as low utility. It helped mainly with material that is easy to picture and on memory tests, not on deeper understanding. The lesson: a vague mental image is weak. A concrete visual that maps the structure of the idea, on paper, is much stronger.

This confusion is common, so it is worth being clear. A 2008 review on learning styles by Harold Pashler and colleagues looked for experiments showing that students learn best when teaching matches their preferred style. They found virtually none, and some well-designed studies contradicted the idea. Dual coding does not ask what kind of learner you are. It says that words plus a good visual beat words alone for most people and most topics.

The last step, redrawing from memory, is where dual coding meets active recall. Looking at a diagram is still passive. Rebuilding it on a blank page and explaining each part out loud forces you to retrieve both codes, and shows you exactly which arrow or label you had forgotten. It works especially well for subjects full of structures, like anatomy.

Here is a quick example. Your biology notes say that in the lungs, oxygen moves from the alveoli into the blood while carbon dioxide moves the other way. As words alone, that is easy to mix up. Draw one small circle for an alveolus, a tube beside it for a capillary, and two arrows pointing in opposite directions, labeled O2 and CO2. Under it, write one sentence: each gas moves from where there is more of it to where there is less. Tomorrow, redraw it on a blank page and say the sentence aloud.

Dual coding for abstract subjects

Abstract ideas can be dual coded too. In economics, draw the graph rather than memorize the sentence. In literature, sketch a character map with arrows for relationships. In law, draw a flowchart of the test a court applies, with yes and no branches. In math, pair each formula with a small diagram of what it measures. The visual does not have to be beautiful. It has to show how the parts relate.

• Decorating instead of explaining. Icons and colors that mean nothing add clutter, not memory.
• Copying a complex textbook figure. You will spend twenty minutes drawing and learn little. Simplify it to what you could redraw.
• Separating words and pictures. Put the explanation right next to the visual, using the same labels, so the two codes link.
• Only looking. A diagram you never redraw from memory is just another page to reread.
• Forcing it everywhere. A list of vocabulary words does not need a flowchart. Use visuals where there is structure to show.

Visual layouts also pair well with other note systems. A branching page is covered in our guide to mind map notes, and image-based cards are explained in anatomy flashcards. Grouping parts of a diagram into a few clusters also uses chunking, which makes big diagrams easier to hold in mind.

A short, well-structured summary is a good starting point for dual coding, because it already separates a chapter into clear sections with key terms. Generate one with LearnKit, then draw one visual per section and explain it in your own words.