Extraneous cognitive load

Extraneous cognitive load is the working memory load experienced by learners as they interact with instructional materials. This is a type of cognitive load that instructional designers do have some ability to control (Chandler and Sweller, 1991). Extraneous cognitive load is often compared with Intrinsic cognitive load.

Examples of extraneous cognitive load
Sweller provides a wonderful example of extraneous cognitive load in his 2006 book, when he describes the two possible ways to describe a square to a student (Clark, Nguyen, and Sweller, 2006). A square is a visual and should be described using a visual medium. Certainly an instructor can describe a square in a verbal medium, but it takes just a second and far less effort for a learner to see what the instructor is talking about when a learner is shown a square, rather than having one described verbally. In this instance, the efficiency of the visual medium is preferred, because it does not unduly load the learner with unnecessary information. This unnecessary cognitive load is described as extraneous cognitive load.

Empirical evidence for extraneous cognitive load
Chandler and Sweller (1991) introduced the concept of extraneous cognitive load. This article was written to report the results of six experiments that they conducted to investigate this working memory load. Many of these experiments involved materials demonstrating the Split attention effect. They found that the format of instructional materials either promoted or limited learning. They proposed that differences in performance, were due to higher levels of the cognitive load imposed by the format of instruction. Later they defined this unnecessary (artificially induced) cognitive load as "extraneous cognitive load."

For further reading

 * Kirschner, P. A., Sweller, J., and Clark, R. E. (2006) Why minimal guidance during instruction does not work: an analysis of the failure of constructivist, discovery, problem-based, experiential, and inquiry-based teaching. Educational Psychologist 41 (2) 75-86
 * Cooper, G. (1990) Cognitive load theory as an aid for instructional design. Australian Journal of Educational Technology. 6(2), 108-113.