Dual coding: words and pictures together#

Picture a bicycle. Now read the word “bicycle.” Did you notice that those felt like two different events inside your head? They were. Your mind keeps two separate channels running — one for language, one for imagery — and when you feed it both at once, you lay down two traces of the same idea instead of one. That is the whole secret of dual coding, and it is one of the most reliable ways to make material stick.

You already use this without naming it. When someone gives you directions, you remember them far better if they sketch the route than if they only talk. When a difficult idea finally clicks, it is often because a diagram and an explanation arrived together and locked into place. Below I show you why this works, and how to do it deliberately so a picture earns its place rather than just decorating the page.

Two channels are better than one#

The psychologist Allan Paivio spent a career on this. His dual-coding theory (Paivio, 1986) says you process and store information through two partly independent systems: a verbal one that handles words and a non-verbal, imagery-based one that handles pictures, sounds and sensations. The two are linked, so an image can trigger its word and a word can call up its image, but each lays down its own memory trace.

The practical payoff is simple. If an idea is stored in only one channel and that trace fades, the idea is gone. If it is stored in both, you have two routes back to it — see the picture and the word follows, or read the word and the image returns. This is also why concrete words (“bicycle”, “lighthouse”) are easier to remember than abstract ones (“justice”, “tendency”): concrete words spontaneously summon a picture, so they get coded twice, while abstract words usually ride on the verbal channel alone.

This is the engine underneath much of Memletics. Visualization works because it forces the imagery channel to fire. Association and the peg-word systems work because they bolt a vivid mental picture onto a word you need to recall. You are not learning a party trick — you are using the architecture of your memory the way it was built to be used.

The multimedia principle — and its honest limits#

Richard Mayer took dual coding into the classroom and the screen, and tested it hard. Across a long programme of experiments he found what he calls the multimedia principle: people learn more deeply from words and pictures together than from words alone (Mayer, 2021). A labelled diagram of how a pump works, paired with a short explanation, beats the same explanation as a wall of text.

But — and this matters — “add a picture” is not a magic wand. Mayer’s research is just as much about what not to do, because the wrong visuals actively hurt. Three findings are worth burning into your habits:

Diagrams that explain, not images that decorate. A picture helps when it carries information the words cannot — structure, layout, a process, how parts relate in space. A stock photo dropped in to “liven things up” adds nothing to learn and quietly competes for your attention.
Beware redundancy. It feels generous to show a diagram, narrate it, and print the same narration on screen as text. It backfires. Mayer’s redundancy principle found that on-screen text duplicating spoken words splits your limited attention and makes learning worse, not better. Say it or show the same words — not both at once.
Keep the related bits together. His contiguity principle says a label should sit next to the part it names, and an explanation should sit beside the picture it explains, not on the page overleaf. When you have to hold a word in mind while you hunt for its picture, you waste the very working memory you needed for understanding.

The reason all three rules point the same way is that each channel has a narrow throat. Pour redundant or decorative material into it and you clog the channel you were trying to help.

Putting it to work#

You don’t need software or artistic talent. You need the discipline to make every visual pull its weight.

When you meet something with parts or steps, draw it. A systems diagram of an engine, a timeline of a war, a flowchart of a procedure — the act of drawing forces you to decide how the pieces connect, and the finished picture gives your imagery channel something to hold.
Pair the picture with a short explanation, side by side. A diagram alone can be ambiguous; words alone can be abstract. Together each covers the other’s weakness. Put the words where the eye lands when it leaves the picture.
Strip the decoration. Before you keep an image, ask: what does this let me learn that the text doesn’t? If the answer is “nothing,” cut it. A clean diagram beats a pretty, busy one.
Don’t make yourself read and listen to the same words. Reciting a definition aloud while reading it off a card is dual verbal, not dual coding — both copies land in the same channel. Pair the spoken or written word with a picture instead.
Speak your mind maps. A mind map is dual coding on paper: spatial layout and colour for the imagery channel, words on the branches for the verbal one. Say each branch aloud as you draw it and you’ve engaged both, plus your own voice.

The takeaway: give your brain the same idea twice, once as a picture and once as words, and let them sit together. A clear diagram beside a clear explanation is worth far more than either alone — and worlds more than a decorative image that only looks like learning.