Whenever the user performance is a primary concern, we should favor consistency over adaptability. In situations when the consistent system behavior is not adequate for particular users, they should be allowed to change the behavior occasionally. However, by no means should they be required to change the system behavior frequently, and by no means may the system change its behavior without the explicit user request or confirmation.
In situations when the consistent system behavior is not adequate for particular users, they should be allowed to change the behavior occasionally. Whenever the user performance is a primary concern, we should avoid adaptability.
Consistency implies efficient learning, fast skill acquisition and better operational reliability.
Whenever possible, define the controls such that the system response to the control activation is consistent, independent of any variables or setup parameters. The response to controls intended for routine operation should be consistent to enable seamless, carefree operation.
Adaptability should be provided only in special situations, in which it is evident that users may be inconvenienced when operating within the designed parameters.
When adaptability is required, the only party eligible to change the system behavior is the operator. The operators should be provided with easy-to-remember access to the setup parameters and should be well informed about the effects of using the non-default values. Adaptability should be minimized and isolated.
Adaptability enables the optimization of the system response according to various considerations. However, adaptability implies inconsistent system response to user actions, which hampers learning and skill acquisition.
Updated on 13 Jul 2016.