For media messages to effectively get through to people the amount of cognitive effort required to process them must be exceeded by the amount of space in working memory. This post will be a summary of some of Richard Mayer’s work on the reduction of cognitive load in multimedia learning.
Mayer uses Wittrock’s generative theory of learning as a base for his research. He identifies three assumptions made by this theory.
- The dual-channel assumption: the human information-processing system consists of two channels, one for visual information and one for auditory/verbal information.
- The limited capacity assumption: the human information-processing system has limited capacity. Either channel can process only a finite amount of information at one time.
- The active-processing assumption: meaningful learning requires substantial amounts of cognitive processing to occur in either channel, in organizing informational input, and in integrating information from both channels into a coherent model of reality.
Multimedia learning has five core processes: (1) selecting words, (2) selecting images, (3) organizing words, (4) organizing images, and (5) integrating. The basic idea is that the learner processes information from both channels, makes sense of this information, and then integrates the information from both channels.
If a diagram about how pumps work includes both images and text, the learner will form a text-based “story” of how pumps work, in addition to an image-based “story” of how pumps work, and then compare the two to make sure they’re both telling the same story. At any one of these five stages, learning can be blocked by cognitive overload.
Mayer and Roxana Moreno distinguish between three types of cognitive demands, any of which might lead to instances of cognitive overload: essential processing demands, incidental processing demands, and representational holding.
Essential processing demands refer to processing that is required in order to correctly make sense of the information. The five core processes in multimedia learning are essential processing.
Incidental processing demands refer to cognitive processing other than the five core processes. It can refer to extraneous information that is not necessary for making sense of the material.
Representational holding refers to the cognitive process of holding a mental representation in working memory over time, possibly while being forced to process other information.
Any of these three demands can overwhelm the learner if the quantity of information is too much or if it is not adequately distributed across the two channels. There are five types of cognitive overload and nine defenses against it.
Unpacking this table will be made easier by focusing on the Description of Research Effects column. It provides ways of combating cognitive overload and facilitating learning.
Mayer's work on multimedia learning is an example of empirical research being done on media effects and effectiveness. Internalizing the sources of and defences against cognitive overload allows us both to better understand the educational effects of media on audiences and to improve our ability to communicate information to others.