The Redundancy Effect
Two common sources of redundant information are the presentation of information that learners already know, and the presentation of information which is already contained within the learning materials.
When semantically identical information is presented in two or more sources, learners need to attend to the multiple sources and consider them mentally. It is only after processing that learners may realise that some is redundant and can be ignored, but they have just expended time and cognitive resources upon processing it.
By removing redundant sources of information, cognitive resources are freed from the task of processing it, thus becoming available to be applied to learning.
Instructional resources should be screened to ensure that all irrelevant information is removed. It should also be ensured that new information is presented only once, in a cognitively cohesive manner rather than being repeated.
When two sources of equivalent information are presented through different media formats, such as graphical and textual, consideration should be given as to which source is preferable to present, and then the other be removed.
Note that this does not mean removal of repeated information from advance organisers or summaries, as these hold a distinct cognitive function.
All instructional materials should be vetted to ensure that all content is essential for the target group of learners.
Information should be presented once only, and special attention should be given to mixed media contexts that may repeat information through different resources.
By way of example, consider graphical resources such as maps, tables or figures. Provided learners have the capacity to fully interpret the graphical resources, the text based statements to the same effect will be redundant.
Information that discusses various details of the content and implications of it is not redundant and can be included in the information.
Consider the following passage about the sun, with repeated information.
The sun rises in the East. The sun rises every morning in the East. The sun gives light. Every morning the sun rises and always does so in the East. No matter where you are on Earth, the sun rise will always rise in the East. You may always determine the direction to East by seeing where the sun rises. The sun gives light and rises every morning and always does so in the East
Consider the following passage about the sun, without repeated information.
The sun gives light and rises every morning in the East.
The meaningful information in each passage is identical. The first passage presents added processing requirements upon the reader, but adds no additional information. The repeated information is redundant and should be omitted.
Consider this passage with the accompanying graphic.
On fridays the overall sales of food are made up of 40% sales of fish and chips, which is the largest selling item, 30% of sales are for hamburgers, 20% of sales are for pizzas and 10% of sales are for 'other' items, which makes up the smallest amount of sales for food items.
The information presented by the passage and the information presented by the graphic are identical. Presenting both of these together increases the amount of processing that a learner needs to do but adds no additional information.
One of these information resources should be removed in its entirety. Under many conditions, the graphical form of this type of information is easier to process than the written passage.
It is recommended in these situations to delete the textual passage.
This schematic graphic indicates blood flow in humans.
The graphic contains the chambers of the heart, the lungs, and the body.
Text labels are used to identify the heart chambers, lungs and body.
Text describes the directional flow of blood through the chambers, lungs and body.
Arrows also indicate the directional flow of the blood through the chambers, lungs and body.
The textual presentation of information about the flow of blood and the arrows depicting information about the flow of blood are identical. One of these souces of information should be removed. Due to the contextual aspect of the graphic, it is desirable to maintain the arrows as the manner in which to indicate information about blood flow.
The information presented in textual form is redundant and should be omitted.
Removing the textual information about blood flow increases learning from these materials. See Chandler & Sweller (1991) for details.
Chandler, P., & Sweller, J. (1991). Cognitive load theory and the format of instruction. Cognition and Instruction,8, 293-332.
Kalyuga, S., Chandler, P., & Sweller, J. (1999). Managing split-attention and redundancy in multimedia instruction. Applied Cognitive Psychology, 13(4), 351–371. http://doi.org/10.1002/(SICI)1099-0720(199908)13:4<351::AID-ACP589>3.0.CO;2-6