Response time is one factor that determines how the user interface (UI) unfolds. Generally, an interface should be fast to give an immediate response to the user. However, an overly fast interface can have the opposite effect, making the user miss important information. Response times depend of different contexts. Below are different response times and when to use them:
0.1 second is the response time limit if you wish to make the user feel that their action is making the system react instantaneously.
This requires no special feedback, as the system response itself serves as the feedback. 0.1 second response times are required in cases such as mouse movements, keyboard presses, and touch interfaces, e.g., selecting something, dragging something, etc.
It should not be used when the user is expected to react or comprehend the content on the interface, such as scroll lists, pop-up messages, etc.
The user’s flow of thought remains uninterrupted in this response time. However, the user does notice a delay. It requires no special feedback. The user notices that it is a two-way interaction between them and the computer. It should not be used where immediate response is needed, such as a drag action on a touch screen interface.
Users cannot stay focused for more than 10 seconds. This is the limit for the user’s short-term memory. The users start to lose information and thus will not be able to resume the interaction very smoothly when the computer finishes the task.
Special feedback is required for this response time. If the delay is between 2 - 5 seconds, then a busy indicator would do. However, if the time required is greater than 5 seconds, then a progress indicator that shows the percentage of progress is required.
A 2 - 5 seconds delay does not break concentration and is acceptable. However, attempts should be made to shorten it if possible. For delays longer than 5 seconds, the latency is large enough to break the user’s concentration. However, this time is not long enough to fill the idle time with other tasks. Attempts should be made to:
Reduce this delay to less than 5 seconds.
Increase the delay to more than 10 seconds, thus giving the user enough idle time to do other tasks in the meantime.
Other response times are longer and require proper feedback. Some response times include:
1 minute: Step-wise progress indicator or percentage-done progress indicator.
10 minutes: Checklist or percentage-done progress indicator.
A progress indicator conveys to the user that the system is working on their task and has not crashed. By informing the user about the progress, it allows the user to carry out other activities while the system is working.
It gives the user something to look at that satisfies them that some progress is being made. A progress bar is preferred over numbers, so the user sees something happening.
In any case, users should be shown that their request is being processed, either in the form of progress indicators or some other indication if exact progress representation is not possible.
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