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Cognitive workload

Cognitive workload relates to the mental effort required to perform tasks. It is a useful diagnostic of situations where users have to expend excessive mental effort to achieve acceptable performance, and is particularly important in safety-critical applications.
Cognitive workload is closely related to comfort: even if a system is apparently acceptable for use, it may be low in comfort if it demands too little or too much mental effort. A task demanding too little mental effort may result in a lowered efficiency because it leads to boredom and lack of vigilance, which directly lowers effectiveness. Excessive cognitive workload may also result in lowered effectiveness, if it causes information to be missed and results in errors. This is a particularly important issue in situations where safety is critical, e.g. air traffic control and process control. Measures of cognitive workload can be used to predict these types of problems.

What is Cognition

A factor relevant to the individual perception of credibility regarding a web site is the perceived efficiency at which the user is able to complete certain tasks on the site. Effective operation of an interactive tool is dependent on the ease at which the user is able to learn the interface and anticipate the navigational schema. To figure out what methods would lend themselves more easily to an interactively ergonomic interface, you need to understand how the mind works, and what processes it goes through to arrive at certain conclusions.

The breadth of research on cognitive theory is much to great to summarize in any kind of specific detail for this site, but highlighting a couple of aspects of the cognitive model of learning might prove useful to any interactive designer.

The process of learning, under the cognitive model, is predominantly an internal process of the individual doing the learning. Most knowledge acquisition is understood as being transmitted in a one-way process from the "teacher" to the "learner." The information is somehow copied exactly from one brain to another. This, however, is not altogether that accurate, given the way the human mind works. The learner is an active processor of information who internally constructs individualized knowledge. Increasing the efficiency of a teaching tool (any web site with information to convey) would require the designer of the tool to re-conceptualize the "teaching" process from a "transmission" model to an "integration" model.

In Instructional Design: Implications from Cognitive Science, the author indicates that new information that is to be "integrated" with a learner must be modified to fit within existing individual knowledge structures called "schemas." For integration to occur successfully, an existing schema must be modified in one of three ways:

  • Accretion (minor additions to existing schema),
  • Tuning (minor modifications to an existing schema), or
  • Restructuring (major modification of an existing schema)

In the case of interactive media, the schema in question is "interaction methods to item(s) I learn from/with." Early web designers were at least instinctively aware of this "Schema Modification Theory," as their designs could be easily identified as alterations of well established metaphors. It was not uncommon in the early days of the world wide web to see sites that functioned almost exactly like a book, table of contents and all. On other sites one might find pages mimicking either an audio tape player or a VCR with images a visitor might click on to stop, go forward, or reverse. These examples of "piggy-backing" on existing visual and organizational metaphors serve as excellent examples of accretion, but are usually understood as only mildly successful in terms of usability.

In hindsight, one can see that these first attempts to allow an individual to successfully navigate and retrieve information from an "interactive" resource were steps toward a more complete schema restructuring. It may be premature to say that an entirely new schema has been constructed, on a socio-cultural level that reflects the "Internet" metaphor, but it is certainly on it's way. Television commercials and advertising have begun to tune their own schemas by including "visual idioms" unique to the world wide web.

It is important to realize that the Internet has begun to integrate itself into the social consciousness in such a fashion that any effort by a web designer to do anything but restructuring would be a step backward. Because the web is a unique medium, it cannot be forced into a television, radio, or library metaphor. Or rather, it can, but it will limit the capabilities of the tool, and thus, the efficiency at which information can be gathered, and knowledge learned.

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Last modified on 27 june 2004

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