By: Megan Smith

Dual coding, or combining words with visuals for learning, can be a great way to promote student learning. The words can be written or spoken, and the visuals can take many forms such as static illustrations, graphs, charts, photos, or maps, or dynamic animations, videos, or interactive illustrations. Dual coding is sometimes called multimedia learning  because the material is represented in multiple forms (1). We have written about how students can use dual coding to help them study and suggested that teachers use dual coding to promote good active learning in the classroom.

The problem:

However, as with most things in life, there’s always a risk of “too much of a good thing.” In other words, sometimes combining too many words and visuals can actually hurt learning. Too much information at once can lead to cognitive overload, where “the learner’s intended cognitive processing exceeds the learner’s available cognitive capacity.” (2, p. 43). If the demands of a learning activity require too much cognitive capacity, then students will not fully benefit from the activity. 

There are many aspects of a learning activity that require cognitive processing. Researchers have identified three different types of cognitive demands (2):

1. Essential processing: Some processing is being used to make sense of the presented material, and meaningful learning can demand substantial cognitive processing. If the material is new and is being presented quickly, a great deal of cognitive capacity would be required to organize and understand the material.

2. Incidental processing: Some processing capacity may be used for nonessential aspects of the learning activity. For example, if background music is added to a narrated animation, a portion of the students’ processing capacity may be used to process the music.

3. Representational holding: Some processing may be used to hold onto important information over time. For example, if a textbook presents words on one page describing an idea and a diagram on the other page illustrating the idea, the student may need to hold onto the verbal information in mind while trying to process the diagram after the page has been turned.

Thus, presenting information to students as words and visuals can help them learn, and learn in a meaningful way. However, if a student experiences cognitive overload trying to process all of the information in a meaningful way, then dual coding can harm learning.

Some solutions:

So, can there be too much of a good thing, like dual coding? Yes, too many different representations at once can lead to cognitive overload. However, cognitive overload can be an obstacle in almost all learning situations. Just because dual coding can lead to cognitive overload doesn’t mean it has to.

Here are some general suggestions about how to reduce cognitive load when using dual coding learning strategies based on research (2).

1.  Slow down the presentation of words and pictures, and break these up into small segments. This way, the student is able to focus on smaller chunks of visual and verbal information at a time. Leaving small breaks in between the segments will help the students fully process the information from one segment before moving onto the next.

2.  If segmenting isn’t possible, providing pretraining about small components of a larger system before presenting the full verbal and visual description. For example, if a student is learning about how car breaks work, they might learn what each individual piece does during pretraining, then move on to learning how all of the components of the system work together using a diagram and a verbal description.

3. If you are presenting a diagram along with a verbal description, try presenting the words as narration. This way, students don’t have to look at the diagram while trying to read the text.

4. Try presenting visuals and written words together so that students do not need to hold onto one representation while trying to process the other. If the words are spoken, narrate at the same time as the visual is presented. In both cases, encourage the students to make connections between the visuals and the words.

5. Remove redundancies. For example, a teacher might present a diagram to students that includes text, and then also provide a verbal description. In this case, remove either the text or the verbal description so they are not processed at once. Presenting the words as spoken words and written words requires additional cognitive processing capacity.

6. When possible, reduce extraneous material (like background music or unnecessary animations). Removing aspects of the material or example that are not essential to the material or example will help reduce cognitive load.*

* Side note: This will work especially well when students are instructed to work with material (i.e., it is not an optional activity). If the activity is optional, reducing interesting aspects could reduce interaction. However, this is an empirical question!

7. Provide cues to the students to help them focus on the most important aspects of the learning activity. For example, telling the students before watching a video to pay attention to the explanation of why something works during the video clip. 

Using some or all of these suggestions can help reduce the chance of cognitive overload while using dual coding. Note, these suggestions are not meant to be a precise recipe for how to construct dual coding learning opportunities, but rather guiding principles that can be flexibly used and considered, when appropriate. Some of these shouldn’t be used at the same time, for example 3 and 4. Tip 3 recommends narrating the words that are presented, while Tip 4 recommends putting words and visuals together on the same page. But, if you do both of these, then you’ll end up with both written and spoken words, which could lead to overload! (See tip 5). But, you could first use tip 3 with one set of visuals, and then have the students work in small groups using Tip 4. You could even try a few of these at different times and space the presentations further improve learning! Use your best judgment, and keep the concept of cognitive overload in mind when designing dual coding learning activities.

The bottom line:

Dual coding can be a very effective way to help students learn, and practice with verbal and visual representations of the material has the potential to be very effective. If in doubt, slow down and repeat, breaking the information down into small chunks before putting them all together in both visual and verbal formats.

References:

(1)  Meyer, R. E., & Anderson, R. B. (1992). The instructive animation: Helping students build connections between words and pictures in multimedia learning. Journal of Educational Psychology, 4, 444-452.

(2) Mayer, R. E., & Moreno, R. (2003). Nine ways to reduce cognitive load in multimedia learning. Educational Psychologist, 38, 43-52.