The Double-Wide: Dual-Coding Theory

Here's your mission, should you choose to accept it. Your goal is to memorize everything that you see in the scene that is linked below. Click on the link, give yourself about 60 seconds to scan the image, then hit the "Back" button on your browser and list as many items as you can.

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Mission: Memorize Me

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What do you remember from the scene? Were there details that were easier for you to remember than others? Did you use any particular strategies to help you encode or recall as many items as possible? What you ultimately remembered likely depends on the strategies you used to encode the scene, or, in other words, the mental representation you used during the encoding process.

Dual-Coding is like a Double-Wide Trailer: Twice the space, Twice the Fun!

So far, we have talked about a couple of different types of mental representations: 

• Mental models are like little mental-simulations of the world; 
• Declarative memories are verbally articulated facts;
• Procedural memories are a series of steps in a skill. 

One property that’s common to all representations is that they are incomplete. This is precisely why representations are useful. Instead of encoding every bit of possible information, representations gloss over unimportant details. The reason for this is computational efficiency. If you had to consider every unique piece of information while running a mental model, then the simulation would go on forever. 

Another property of representations is that some are better suited for specific tasks than others. Some tasks, perhaps like the one above in which you are trying to remember details of a visual image, are easier when we envision a mental picture. For other tasks, however, such as remembering items in a shopping list, it might be more useful to rely on verbal labels, either in written or acoustic form [1].

In many cases, it is possible to use more than one type of representation for the same thing. Concrete nouns, like ocean for example, can be represented in at least three ways:

1. Orthographic Representation: a string of printed characters (e.g., in English: ocean or in Japanese: 海);
2. Phonologic Representation: a sound (e.g., in English: |ˈōSHən| or in Japanese: |ooME|);
3. Imagistic Representation: an image.

In its simplest form, the dual-coding theory proposes that an individual is more likely to retrieve information from long-term memory when the memory was initially encoded with multiple representations [2]. I am more likely to retrieve facts about the concept ocean if I have multiple routes to that pieces of information in long-term memory. That’s why dual-coding seems to work. Thus, a great way to learn a new vocabulary word would be to experience all three representations simultaneously:

Of course, life is not so simple. Most of the interesting things you want to learn about are not concrete nouns. Instead, you are more likely tasked with learning abstract concepts, like equivalent ratios and linear relationships.

A STEM Example

The same strategy that works for learning new vocabulary words also applies to mathematical instruction. It’s not that we strictly need to present a picture, word, and a sound all at the same time for each new concept. Instead, we can use multiple representations that all target the same concept. 

Let's take equivalent ratios as an example. According to Brian Wilson, there are roughly "two girls for every boy" in Surf City. How might we represent that ratio with an arbitrary number of boys?  It turns out that ratios can be represented in (at least) three different ways. 

First, the ratio can be represented symbolically: "2 girls : 1 boy" or "2 girls / 1 boy"

Second, the two numbers can be can plotted against each other on a double number line, like this:

Finally, if you rotate one of the axes ninety degrees, you form a Cartesian coordinate system; thus, the set of equivalent ratios all fall along the linear function:

If all three representations are used in a lesson about equivalent ratios, students are more likely to be able to recall and apply what they learned about equivalent ratios at a later time because they have three routes to get to the same concept. 

Share and Enjoy! 

Dr. Bob

For More Information

[1] More on memorizing lists later. In a later post, we will talk about memorization strategies that are thousands of years old (e.g., the memory palace strategy).

[2] Paivio, A (1969). Mental Imagery in associative learning and memory. Psychological Review, 76(3), 241-263..