Dual Coding: Why Combining Words and Images Strengthens Your Memory

Spatial & Visual Method · Encoding Strategy · Foundational Principle

Read the word "elephant" and your brain does something it does not do for the word "justice." In addition to processing the word itself, it automatically generates a mental image — a large gray animal with a trunk and tusks. That image is a second memory trace, independent of the verbal one, and it makes "elephant" significantly easier to remember than "justice" even though both are common English words. This asymmetry — concrete words are remembered better than abstract words — was one of the observations that led Canadian psychologist Allan Paivio to develop dual coding theory in the 1970s, and it remains one of the most reliable and practically useful findings in memory research. This page is part of the Memory Techniques resources available through Cognitive Train.

The core idea is simple: information encoded in two formats — verbal and visual — is remembered better than information encoded in only one. Two codes mean two independent retrieval paths. If you cannot retrieve the word, the image may still be accessible, and vice versa. This principle underlies virtually every effective mnemonic technique, from the Method of Loci to the Peg System to keyword methods for vocabulary learning. Understanding dual coding is understanding why those techniques work.

What Is Dual Coding Theory?

Dual coding theory, proposed by Allan Paivio in 1971 and refined over subsequent decades, holds that human cognition operates through two distinct but interconnected systems: a verbal system that processes language (words, sentences, narrative) and a nonverbal system that processes imagery (mental pictures, spatial layouts, sensory experiences). These systems can operate independently, but they can also work together — and when they do, the resulting memory is stronger than either system produces alone.

The verbal system encodes information as "logogens" — mental representations of words and linguistic structures. The nonverbal system encodes information as "imagens" — mental representations of objects, scenes, and sensory experiences. When you read the word "dog," the verbal system activates. When you also picture a specific dog — your dog, a golden retriever, a puppy — the nonverbal system activates as well. Now there are two traces in memory rather than one, and either trace can serve as a retrieval cue for the other.

This is not merely a theory — it is one of the most replicated findings in memory research. The "concreteness effect" (concrete words are remembered better than abstract words) and the "picture superiority effect" (pictures are remembered better than words) are both direct predictions of dual coding theory, and both have been confirmed in hundreds of experiments.

Why Does Dual Coding Work? The Science

The effectiveness of dual coding has been demonstrated so consistently that it is considered one of the most robust effects in cognitive psychology. Several mechanisms contribute to its power.

Redundant retrieval paths. The most straightforward explanation: two codes provide two independent routes to the same memory. If the verbal trace degrades, the visual trace may still be intact, and vice versa. This redundancy makes the memory more resilient to forgetting. A study by Paivio and Csapo (1973) demonstrated that items encoded with both verbal labels and images were recalled significantly better than items encoded with only one format — a finding that has been replicated many times since.

Deeper processing. Creating a mental image of a word or concept requires more processing effort than simply reading or hearing it. This additional processing — translating from one format to another — produces a deeper encoding trace. This aligns with the levels of processing framework: the more elaborately information is processed at encoding, the better it is retained.

Distinct neural substrates. Brain imaging research has confirmed that verbal and visual processing engage different brain regions. Verbal processing activates left-lateralized language areas (including Broca's and Wernicke's areas), while visual imagery activates occipital and parietal regions involved in visual processing. When both systems are engaged during encoding, the memory trace is distributed across a wider network of brain regions, making it more robust.

The picture superiority effect. Pictures are generally remembered better than words — a finding demonstrated by Shepard (1967), who showed that recognition memory for pictures exceeded 90% even after viewing hundreds of images. Paivio's explanation is that pictures automatically activate both the visual and verbal systems (you see a dog and also think the word "dog"), while words activate the verbal system readily but the visual system less automatically. Pictures get dual coded by default; words often do not — unless you deliberately create an image.

How to Use Dual Coding

When studying text, create mental images. As you read each key concept, pause and generate a vivid mental picture of what it describes. Do not just understand the concept verbally — see it. If you are studying the circulatory system, picture blood flowing through arteries, the heart pumping, valves opening and closing. The image does not need to be anatomically perfect — it needs to be vivid and personal.

Draw diagrams and sketches. You do not need to be an artist. Rough sketches, diagrams, flowcharts, and mind maps all force you to translate verbal information into visual form. The act of drawing — even badly — engages the visual system in a way that re-reading does not. Research on the "drawing effect" by Wammes, Meade, and Fernandes (2016) showed that drawing words produced significantly better recall than writing them, even when drawing time was limited to just four seconds per item.

Use concrete examples for abstract concepts. Abstract ideas ("inflation," "democracy," "entropy") are hard to visualize directly. But concrete examples of those concepts can be visualized. Inflation becomes a mental image of a shopping cart with the same items but a higher price tag on the receipt. Democracy becomes an image of people standing in line to vote. Converting abstract to concrete is how you give the visual system something to work with.

Combine text and images in study materials. When creating notes, flashcards, or summaries, include both words and images — a diagram next to the explanation, a sketch alongside the definition. This is not decoration; it is creating two encoding formats for the same information. Flashcard apps that support images alongside text leverage dual coding directly.

Narrate images and visualize narration. The principle works in both directions. When looking at a diagram, chart, or image, describe it to yourself in words — what is happening, what each part represents, how the elements relate. When reading text, generate the corresponding image. Each translation between formats strengthens the dual code.

Dual Coding in Other Memory Techniques

Dual coding is not just a standalone strategy — it is the underlying mechanism that makes most advanced mnemonic techniques effective.

Method of Loci — when you place an item at a location in your memory palace, you are creating both a verbal association (this item goes here) and a vivid visual image (the item interacting with the location). The Method of Loci is, at its core, a systematic application of dual coding combined with spatial memory.

Peg System — when you link a list item to a numbered peg through a vivid image, you are encoding the item both verbally (its name and position number) and visually (the interaction image). The peg system's instructions to make images bizarre and exaggerated are instructions to maximize the strength of the visual code.

Major System — converts numbers (abstract, hard to visualize) into words (concrete, easy to visualize). The number 42 becomes "rain" — now you have both a verbal code (the word "rain") and a visual code (a mental image of rain). The Major System is essentially a dual-coding tool for numerical information.

Keyword method for vocabulary. When learning a foreign word, you find a similar-sounding word in your native language and create a mental image linking the two meanings. The Spanish word "pato" (duck) sounds like "pot" — so you picture a duck sitting in a cooking pot. The verbal link (sound similarity) and the visual link (the image) create a dual code that makes the vocabulary item far more memorable than rote repetition.

Dual Coding vs Other Memory Strategies

Dual coding vs elaborative encoding — elaborative encoding connects new information to existing knowledge through meaningful associations. Dual coding connects the same information to two different representational formats. They are complementary: elaborative encoding deepens the verbal trace, while dual coding adds a visual trace. Using both (elaborately encoding information while also creating images for it) produces the strongest memory traces.

Dual coding vs active recall — dual coding is an encoding strategy (how you put information in), while active recall is a retrieval strategy (how you get information out). They address different stages of the memory process and combine naturally: dual-code the material during study, then use active recall during review to strengthen both traces.

Dual coding vs chunking — chunking reduces memory load by grouping items. Dual coding strengthens individual memory traces by encoding them in two formats. For complex material, you might chunk it first (reducing the number of items) and then dual-code each chunk (strengthening each item). The strategies operate at different levels and combine effectively.

Common Mistakes with Dual Coding

Passive image viewing is not dual coding. Looking at a textbook diagram while reading the caption is not enough. For dual coding to work, you need to actively process both the image and the text and connect them. Describe the diagram to yourself in words. After reading the text, close your eyes and try to generate the image from memory. The active translation between formats is what creates the dual code — passive exposure to both formats side by side does not.

Decorative images do not help. Research on multimedia learning has shown that images which are decorative (a stock photo of a brain next to an article about memory) do not improve learning — and can actually distract from it. For dual coding to work, the image must represent the same information as the text in visual form. A diagram of how working memory operates helps. A generic brain illustration does not.

Abstract concepts need concrete translation. Dual coding is hardest with abstract material because there is nothing obvious to visualize. The solution is not to skip the visual code — it is to find or create a concrete representation. Metaphors, analogies, and concrete examples all serve as bridges from abstract concepts to visualizable images. This translation step takes effort, but that effort is itself part of what makes the encoding effective.

You can experience the dual coding advantage directly by trying the Visual Memory Test (which relies primarily on visual encoding) and the Word Span Test (which relies primarily on verbal encoding) — then notice how items that you can both name and visualize are easier to recall than items you can only process in one format.

Explore more techniques: Method of Loci · Peg System · Elaborative Encoding · Active Recall · All Memory Techniques