The first law of interface design is User Control: The interface will allow the user to perceive that they are in control and will allow appropriate control.
Users need to feel they are in control of the computer.
To be comfortable using a computer, users need to feel they are in control of the computer, and not the other way around. If users feel they are not in control, they may react emotionally. How this reaction plays out depends on the individual, but some common manifestations of a user feeling not in control can include anger, apathy, resentment, and confusion.
At the very least this will result in more errors, and at its worst, users may stop using the interface/application altogether if they feel they are not in control.
There is a difference, however, between feeling in control and being in control. For some actions, users actually need to be in control, but there are other times when the user may feel in control but not necessarily be in control. Users who feel in control can do the following:
- Predict what the computer will do next
- Take the next action they decide is appropriate
- Go back and fix problems they discover
- Do their work the way they want to, instead of changing their work to fit the way the computer wants them to do it
Technology Considerations and Implications
In a GUI application the computer is “only” a screen, and it is easier for the person to feel they are in control. But in a speech application where the computer is speaking, ...