Mayer, R. E. and Moreno, R. (2003) Nine ways to reduce cognitive load in multimedia learning. Educational Psychologist, 38(1), 43-52.
The authors base this study on three logical assumptions:
- Dual-channel assumption. Humans have separate “channels” for processing pictures and words. Our brains understand visual information with one channel, and verbal information with another.
- Limited-capacity assumption. Each of these two channels can only process so much at one time.
- Active-processing assumption. According to the authors, “meaningful learning involves cognitive processing including building connections between pictorial and verbal representations” (43).
In other words, while we can present unlimited amounts of images, animations, narration, text, etc., students can only process a limited amount. The authors explain: “A central challenge facing designers of multimedia instruction is the potential for cognitive overload – in which the learner’s intended cognitive processing exceeds the learner’s available cognitive capacity” (43). Instructional designers and teachers must be aware of cognitive load as they create an implement multimedia instruction in their courses.
Next, the authors present strategies that designers can take in order to reduce the cognitive load in multimedia learning.
Strategy #1: Off-loading. Asking one channel (either the pictorial channel or the verbal channel) to do too much can increase a student’s cognitive load. In other words, instead of displaying a picture and written text, choose to display the picture with narration (45). “Off-load” or reassign some of the content to another channel.
Strategy #2 and #3: Segmenting and pre-training. Complex information presented too quickly in both channels can increase a student’s cognitive load. The first solution the authors present for this type of overload is segmenting, in which a presentation is broken up into “bite-sized segments” (47). If segmenting is not possible, the authors suggest pretraining, which involves giving students instruction before they encounter the multimedia component. If a video will include glossary terms, for example, define the terms before asking students to view the video. I could see how both of these strategies have the potential to effectively reduce cognitive load. If students have frequent breaks (rather than a continuous flow of complex content) and are well-prepared for complex multimedia lessons, they will be able to more readily process the content.
Strategy #4 and #5: Weeding and signaling. Extraneous information included in multimedia instruction can increase a student’s cognitive load. The first solution to this problem is weeding, or, “making the narrated animation as concise and coherent as possible” (48). If weeding still does not reduce the cognitive load sufficiently, the authors suggest “signaling,” or indicating to students what information is most important (using bold text, arrows, headings, an outline, etc.) This is also a logical recommendation. I know from practical experience that a really flashy PowerPoint transition can distract from the content. Similarly, looking at a page full of text (without any headings, page breaks, etc.) is overwhelming. Weeding and signaling address these types of cognitive overload.
Strategy #6: Aligning words and pictures. Students’ cognitive load can be increased in situations where pictures and text are not aligned, since this requires them to “scan” the screen. The solution to this particular problem is to align the words and pictures.
Strategy #7: Eliminate redundancy. I have found that instructors and designers sometimes assume that presenting information in as many ways as possible will help students to better learn the content. The authors argue that, in multimedia instruction, this isn’t necessarily the case. Animation, narration, on-screen text, and/or pictures, all on the screen at the same time, only adds to student cognitive load. To me, it is logical that reducing duplication of content will reduce student cognitive load. Simple, intentional design is best when it comes to cognitive load.
Strategy #8 and #9: Synchronizing and individualizing. Multimedia instruction that requires students to hold information in working memory too long can tax student’s cognitive capabilities (49-50). To reduce this type of cognitive load, the authors suggest synchronizing, or presenting information simultaneously (“here’s a slide with an image and narration”), rather than successively (“here’s an image on one slide, now here’s another slide with text explaining the image you just saw”).
If synchronizing isn’t possible, the authors suggest “individualizing.” While I found all of the other design strategies to be logical and sound, I am hesitant to say the same about this final strategy. According to the authors, individualizing means that you make sure your learners have “high-spatial” ability, since it’s been proven that learners with “high-spatial ability” can hold more in their working memory. This does not seem like a practical suggestion since it requires your students to possess a particular quality. It also seems out of place: all of the other strategies are design recommendations, while this final strategy is more about intrinsic student characteristics. Perhaps if the authors had chosen to frame it differently, it would have made more sense to include it.
This critique aside, this article provides an excellent list of design considerations for multimedia instruction. It is worth noting, too, that the authors support each of these recommendations with solid, evidence-based research, including some of their own original research. For example, in order to support the strategy of weeding, the authors cited a study performed at their lab which demonstrated that students did better on a test after viewing a concise narrated animation than after viewing an embellished narrated animation.
The final critique I would provide is that this article was quite technical. While this may seem ironic for an article on decreasing cognitive load, it contained an overwhelming amount of terms, definitions, and classifications. For example, it lists 3 assumptions, 3 kinds of cognitive demands, 5 cognitive processes, 5 modes of knowledge representation, 5 types of cognitive overload, and 9 strategies for reducing cognitive load. Each of these lists includes more terms, defined by the authors. This is quite a lot for an 11-page article! Perhaps the authors are exercising strategy #9, and assuming that the readers of this article are high-spatial learners who are able to hold a lot of information in their working memories.