Many would agree that people learn better when they can build on what they already understand (known as a schema), but the more a person has to learn in a shorter amount of time, the more difficult it is to process that information in working memory. Consider the difference between having to study a subject in one's native language versus trying to study a subject in a foreign language. The cognitive load is much higher in the second instance because the brain must work to translate the language while simultaneously trying to understand the new information.
Another aspect of cognitive load theory involves understanding how many discrete units of information can be retained in short term memory before information loss occurs. An example that seems to be commonly cited of this principle is the use of 7-digit phone numbers, based on the theory that most people can only retain seven "chunks" of information in their short term memory. Refer to Chunking (psychology).
"Cognitive load theory has been designed to provide guidelines intended to assist in the presentation of information in a manner that encourages learner activities that optimize intellectual performance" (Sweller, van Merriënboer, and Paas, 1998, p. 251). Sweller's theory employs aspects of information processing theory to emphasize the inherent limitations of concurrent working memory load on learning during instruction. It makes use of schemas as the unit of analysis for the design of instructional materials.
John Sweller developed cognitive load theory while studying problem solving . While studying learners as they solved problems, he and his associates found that learners often use a problem solving strategy called means-ends analysis. He suggests problem solving by means-ends analysis requires a relatively large amount of cognitive processing capacity, which may not be devoted to schema construction. Instead of problem solving, Sweller suggests Instructional designers should limit cognitive load by designing instructional materials like worked-examples, or goal-free problems.
In the 1990s, Cognitive load theory was applied in several contexts and the empirical results from these studies led to the demonstration of several learning effects: the completion-problem effect ; Modality effect ; Split-attention effect ; the Worked-example effect and the expertise reversal effect .
Sweller provides a wonderful example of extraneous cognitive load in his 2006 book, when he describes two possible ways to describe a square to a student . 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 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. This is because it does not unduly load the learner with unnecessary information. This unnecessary cognitive load is described as extraneous cognitive load.
Paas and van Merriënboer (1993) developed a construct (known as relative condition efficiency) which helps researchers measure perceived mental effort, an index of cognitive load. This construct provides a relatively simple means of comparing instructional conditions. It combines mental effort ratings with performance scores. Group mean z-scores are graphed and may be compared with a one-way ANOVA.
Paas and van Merriënboer (1993) used relative condition efficiency to compare three instructional condition (worked examples, completion problems, and discovery practice). They found learners who studied worked examples were the most efficient, followed by those who used the problem completion strategy. Since this early study many other researchers have used this and other constructs to measure cognitive load as it relates to learning and instruction (Paas, Tuovinen, Tabbers, & Van Gerven, 2003).
Identifying the processing capacity of individuals could be extremely useful in further adapting instruction (or predicating the behavior) of individuals. Accordingly, further research would clearly be desirable. It should be cautioned that this type of research is very demanding. First, it is essential to compute the memory load imposed by detailed analysis of the processes to be used. Second, it is essential to insure that individual subjects are actually using those processes. The latter requires intensive pre-training.
For Ergonomics Standards See
ISO 10075-1:2000 Ergonomic Principles Related to Mental Work-load - Part 1: General Terms and Definitions
ISO 10075-2:2000 Ergonomic Principles Related To Mental Workload - Part 2 - Design Principles ISO 10075-3:2004 Ergonomic Principles Related To Mental Workload - Part 3: Principles And Requirements Concerning Methods For Measuring And Assessing Mental Workload