This paper uses the analysis of human error to provide a tool for the development of principles of system design, both to minimize the occurrence of error and to minimize its effects. Eventually, it should be possible to establish a systematic set of guidelines, with explicit, quantitative cost-beneflt tradeoffs that can lead toward a design discipline -- a "Cognitive Engineering." This short note starts the process.

Donald Norman has a gift for writing about system design clearly and cogently. His central argument is that human error is caused by poor design. Thus, good designers can minimize end-user errors by understanding basic principles of human cognition. Though written in 1983, the advice remains true for designers of any systems, including web sites and learning systems.
In this article, Norman classifies several types of ‘slips’, which are errors that occur in carrying out an intended action:
‘Mode’ error occurs where one button is given multiple functions, and there is insufficient system feedback as to the current mode. Ideally each button or switch in a system should only represent one function.
‘Description’ error occurs when either operations or the mechanisms to follow through with the operations are too similar. A low risk example is a system where upper and lower case keystrokes of the same key result in different operations; a high stakes example would be a nuclear power plant with identical looking switches and controls with very different resultant operations.
‘Capture’ error results when two different operations can be combined with one command, making the combination of commands automatic. Norman gives an example of a combination UNIX command, “:wq” which conveniently combines two separate commands: write and quit. However, the sequence becomes so automatic process that users who may not want to quit still combine the command, producing an unintended action.
Finally, ‘activation’ error occurs either when a command produces an unintended result or when an intended command is not carried out. These occur due to memory failures, so designing a system to bolster the user’s memory during a process can help prevent these errors.
Examining potential user errors can help inform system design. Norman presents several strategies for preventing these errors, including building in feedback mechanisms to inform users of system states, creating distinctive menu patterns for different command sequences, making actions reversible, and making irreversible actions difficult to do. Finally creating a system with consistent structure and menu design and redisplaying data for the user can help mitigate memory failures that occur in the process of working with a system.
Quelle: [www.elearning-reviews.org]