Dual Coding: Combining Words and Pictures

The core idea

Dual coding is the idea that we process information through two broad channels, a verbal one for words and a visual one for images, and that learning an idea in both forms can help you remember and use it. The theory is associated with the psychologist Allan Paivio, who developed it from the 1970s onward. Put simply, if you can reach a memory through a description and also through a picture, you have two routes to it instead of one.

This is a useful study principle, but it is easy to overstate. Pictures are not magic, and the research does not say that adding any image improves learning. It says that well-chosen visuals paired with clear words can help, especially for ideas that have a spatial, sequential or structural shape.

Dual coding is not learning styles

A common confusion is to treat dual coding as a version of the claim that some people are “visual learners”. They are different ideas. The learning styles claim says you should be taught in your preferred format. Dual coding says that nearly everyone may benefit from combining formats, whatever their preference. The evidence on styles is weak, as discussed under the learning styles myth, while the case for combining words and relevant visuals is more consistent, though still dependent on the material and design.

When pictures help most

Visuals add the most when the content has structure that text describes awkwardly. Typical cases include:

• Processes and cycles. The water cycle, a sequence of steps in a procedure, or how a request travels through a system are easier to follow when you can see the order.
• Relationships. Family trees, hierarchies, cause-and-effect chains and comparisons are natural for diagrams and concept maps.
• Spatial information. Maps, anatomy, floor plans and geometry are hard to convey in words alone.
• Quantities. A simple graph often shows a trend more quickly than a paragraph of numbers, provided it is drawn clearly. The article on basic charts covers good habits there.
• Time. A timeline can show the order and spacing of events in history or in a project.

By contrast, a decorative image of a smiling person next to a paragraph on tax rules adds little. Researchers working on multimedia learning have found that irrelevant pictures, extra animation or background music can compete for attention and sometimes make learning worse.

Why the combination can work

There are a few plausible reasons, and they are not mutually exclusive. First, two representations give you more cues for recall. If you forget the wording, the layout of a diagram may bring it back, and vice versa. Second, making a diagram requires you to decide how ideas connect, which is an active form of thinking rather than copying. Third, offloading structure to a picture can reduce the load on working memory, since the relationships are visible on the page instead of being held in your head. This links to what the article on cognitive load describes.

A caution on the third point: a diagram that is overloaded with detail does the opposite. Keep each one focused on a single idea.

Practical ways to use it

You do not need drawing skill. Stick figures, boxes and arrows are enough.

1. Sketch after reading. After a section, close the book and draw the main idea from memory, then check against the text. This doubles as retrieval practice.
2. Add labels, not paragraphs. On a diagram, use short labels and keep explanation in the text beside it. Place labels close to what they describe so you do not have to hunt for them.
3. Convert notes into visuals. Take a page of linear notes and turn it into a flowchart, a table or a mind map. Compare the formats in the article on note-taking methods.
4. Use timelines for sequences. Drawing events along a line helps you see gaps and overlaps.
5. Explain a diagram aloud. Describe in your own words what each part shows. If you struggle, you have found something to revisit.
6. Design flashcards with both sides. A card might have a short prompt on one side and a simple sketch on the other, or a diagram with one label missing. See flashcard design for more on making cards useful.

A small example

Suppose you are learning how a bill becomes law in a legislature. Do not worry about the exact country; the principle is the same. In words, you might write that a proposal is introduced, discussed in committee, voted on in each chamber and then signed. As a diagram, you draw boxes in a row: introduced, committee, first vote, second vote, signature, with arrows between them and a branch showing where a bill can be sent back. The sketch shows where the process can loop, which the sentence hides. Later, trying to redraw it from memory tests both the order and the branching.

Pitfalls to avoid

• Copying without thinking. Tracing a diagram from a textbook can feel productive but may involve little processing. Try drawing it without looking.
• Too much on one page. If a diagram needs five minutes to decode, split it.
• Assuming accuracy. A neat picture can be wrong. Check diagrams against reliable sources, particularly ones you made from memory.
• Ignoring accessibility. Some learners cannot see images well, so a good diagram should have a written description alongside it. That helps everyone check their understanding.

What to expect

Studies on combining words and pictures generally show benefits when the visuals are relevant and well designed, but the size of the effect varies, and much of the research uses short lessons and immediate tests. Learners with lots of prior knowledge sometimes gain less. A reasonable approach is to try it on material with obvious structure, check whether you can explain it afterwards without looking, and keep what works for you.