Dual coding: why words plus pictures stick better

You read the same page on the Krebs cycle three times and it still slides right off. Then a friend draws it as a circle on a napkin, with arrows and a few labels, and suddenly you can see it. A week later, that napkin is what you remember, not the page.

The short version

Dual coding means learning an idea in two forms at once: as words and as a picture that shows how it works. Your memory stores the two in different ways and links them, so you have two routes back to the idea instead of one. It is not about being a "visual learner". It works for nearly everyone, as long as the picture actually shows the idea.

What dual coding is

The idea comes from Allan Paivio, a Canadian psychologist, who laid it out in his 1971 book Imagery and Verbal Processes (Paivio, 1971). His claim was simple. Your mind has two separate but connected systems: one for language (words, sentences, definitions) and one for images (shapes, scenes, how things are laid out in space). The two systems are linked, so a word can call up an image and an image can call up a word.

That explains a pattern that shows up again and again in memory research: concrete material is easier to remember than abstract material. As Paivio and his colleague James Clark put it in a later review, "concrete phrases, sentences, and paragraphs are remembered better than abstract text" (Clark & Paivio, 1991). "Apple" is easy to picture, so it gets stored twice. "Justice" is hard to picture, so it often gets stored only once.

You cannot change how abstract your course is. But you can give an abstract idea a picture: a diagram, a timeline, a flowchart, a sketch. That is the whole move.

The key studies

Pictures are very memorable. In 1973, Lionel Standing showed volunteers 10,000 pictures, 5 seconds each, spread over five days. About two days later, he tested them by showing two pictures side by side, one old and one new, and asking which they had seen. From their scores, he estimated they had kept around 6,600 of the 10,000 pictures in memory, after seeing each one only once. In a smaller version with 100 items, people held on to about 90 pictures but only about 70 words (Standing, 1973).

Words and pictures together beat either one alone. Richard Mayer and Richard Anderson showed college students with no mechanics background an animation of how a bicycle tire pump works. Some heard the explanation while they watched. Others heard it before the animation, or got only the words, or only the animation. The students who got words and pictures at the same time did best on problem-solving questions, the kind where you have to use the idea, not just repeat it (Mayer & Anderson, 1991).

Mayer kept testing this for years. In his book Multimedia Learning, he counted 11 experiments that compared words alone with words plus pictures. Words plus pictures won in all 11, with a median effect size of 1.39 (Mayer, 2009). In plain terms, that is a big difference, much bigger than most study tricks produce.

Drawing it yourself may be even better. In a series of experiments, Jeffrey Wammes, Melissa Meade and Myra Fernandes gave students a list of simple words like "apple" and asked them either to draw each one or to write it out again and again. Later, students often recalled more than twice as many drawn words as written ones. Drawing still won when it was compared with imagining the object or looking at a picture of it. Art skill did not matter, and even 4 seconds of drawing helped (Wammes, Meade & Fernandes, 2016). One honest caveat: these were single words that are easy to draw, not whole chapters.

Why it works

Think of each memory as something you have to find again later. If an idea is stored only as a sentence, you have one path to it. If it is also stored as an image, you have two, and they are linked. When one path fails during an exam, the other can still get you there.

There is a second reason. To turn text into a diagram, you have to decide what the parts are and how they connect. That act of organizing is thinking, and thinking about meaning is what makes things stick. A diagram you made yourself is a record of your own understanding.

Where it falls short

Dual coding is not learning styles. This is the big myth. Many people believe they are a "visual learner" or an "auditory learner" and should study only in that format. In 2008, Harold Pashler and three other memory researchers reviewed the evidence. To support learning styles, a study would need to show that visual learners do best with pictures and verbal learners do best with words. They found "virtually no evidence" for that pattern, and concluded there was "no adequate evidence base" for using learning style tests in schools (Pashler et al., 2008). Dual coding says the opposite: words plus pictures help nearly everyone, whatever they think their style is.

Decorative pictures do not count. A stock photo of a smiling student on a slide about cell division adds nothing. Worse, extra material can get in the way. Mayer calls this the coherence principle: people learn better when extra, unneeded material is left out. In his count, cutting the extras helped in 13 of 14 tests (Mayer, 2009). The picture has to show the idea itself, like how the parts connect, what happens in what order, or what causes what.

It is not a magic fix. Some ideas are hard to draw, and a diagram you only glance at will not stay with you on its own. Dual coding works best together with other habits, especially testing yourself.

How to use it yourself

• Sketch it. After reading a section, close the book and draw the idea from memory. Boxes and arrows are fine. Ugly is fine.
• Change the format. Turn a list of events into a timeline, a process into a flowchart, a comparison into two columns, a system into a labeled diagram.
• Explain the drawing in words. Point at each part and say what it does, out loud or in writing. This is where the two codes get linked.
• Put words and picture together. Labels go on the diagram, not in a separate box under it.
• Redraw it later. A week on, try the diagram again from a blank page. The gaps show you what to review.

Tip: if you cannot draw it, you probably do not understand it yet. That is useful to know before the exam, not during it.

How lezrn uses it

lezrn gives you a picture next to the words. While you read a lesson, Visuals can draw a diagram of the exact idea you are on and save it with the lesson, so the words and the picture stay together.

• Visuals and interactive explainers show the idea, not decoration. See Visuals and explainers.
• Mind maps lay out the ideas in a lesson and how they link.
• The AI tutor teaches on a whiteboard, out loud, step by step, and you can explain it back.
• Feynman mode has you explain a concept in your own words, then shows your Strengths, Gaps, Misconceptions and Refine like this. See recall tools.

Sources

1. 1Clark, J. M., & Paivio, A. (1991). Dual coding theory and education. Educational Psychology Review, 3(3), 149 to 210. https://doi.org/10.1007/BF01320076
2. 2Mayer, R. E. (2009). Multimedia learning (2nd ed.). Cambridge University Press. https://doi.org/10.1017/CBO9780511811678
3. 3Mayer, R. E., & Anderson, R. B. (1991). Animations need narrations: An experimental test of a dual-coding hypothesis. Journal of Educational Psychology, 83(4), 484 to 490. https://doi.org/10.1037/0022-0663.83.4.484
4. 4Paivio, A. (1971). Imagery and verbal processes. Holt, Rinehart and Winston.
5. 5Pashler, H., McDaniel, M., Rohrer, D., & Bjork, R. (2008). Learning styles: Concepts and evidence. Psychological Science in the Public Interest, 9(3), 105 to 119. https://doi.org/10.1111/j.1539-6053.2009.01038.x
6. 6Standing, L. (1973). Learning 10,000 pictures. Quarterly Journal of Experimental Psychology, 25, 207 to 222. https://doi.org/10.1080/14640747308400340
7. 7Wammes, J. D., Meade, M. E., & Fernandes, M. A. (2016). The drawing effect: Evidence for reliable and robust memory benefits in free recall. Quarterly Journal of Experimental Psychology, 69(9), 1752 to 1776. https://doi.org/10.1080/17470218.2015.1094494