Effective Feedback
Providing the Proper Feedback
To be
effective, feedback to the user for an action must occur within certain time
limits.
Excessive
delays can be annoying, interrupt concentration, cause the user concern, and
impair productivity as one’s memory limitations begin to be tested.
Response Time
System responsiveness should match the speed and
flow of human thought processes.
If
continuity of thinking is required and information must be remembered
throughout several responses, response time should be less than one or two
seconds.
If human
task closures exist, high levels of concentration are not necessary, and
moderate short-term memory requirements are imposed; response times of 2 to 4
seconds are acceptable.
If major
task closures exist, minimal short-term memory requirements are imposed;
responses within 4 to 15 seconds are acceptable.
When the
user is free to do other things and return when convenient, response time can
be greater than 15 seconds.
Constant delays are preferable to variable delays.
Dealing with Time Delays
Button click acknowledgement:
o
Acknowledge all button clicks by visual or aural
feedback within one-tenth of a second.
Waits up to 10 seconds:
o
If an operation takes 10 seconds or less to
complete, present a “busy” signal until
the operation is complete.
Display, for example, an animated hourglass
pointer.
Waits of 10 seconds to 1 minute:
o
If an operation takes longer than 10 seconds to
complete, display:
§ A rolling
barber’s pole or other large animated object.
§ Additionally,
a progress indicator, percent complete message, or elapsed time message.
Waits over 1 minute:
o
Present an estimate of the length of the wait.
o
Display a progress indicator, percent complete
message, or elapsed time message.
o
When a long operation is completed, present an
acknowledgment that it is
o
completed.
§ A
significantly changed screen appearance.
§ An
auditory tone.
o
If an operation is very time-consuming:
o
Consider breaking the operation into subtasks and
providing progress indicators for each subtask.
o
Allow users to start a new activity while waiting.
Long, invisible operations:
o
When an operation not visible to the user is
completed, present an acknowledgment that it is completed.
o A
message.
o An
auditory tone.
Progress indicator:
o
A long rectangular bar that is initially empty but
filled as the operation proceeds.
§ Dynamically
fill the bar.
§ Fill it
with a color or shade of gray.
§ Fill it
from left to right or bottom to top.
Percent complete message:
o
A message that indicates the percent of the
operation that is complete.
o
Useful if a progress indicator takes too long to
update.
Elapsed time message:
o
A message that shows the amount of elapsed time
that the operation is consuming.
o
Useful if:
§ The
length of the operation is not known in advance.
§ A
particular part of the operation will take an unusually long time to complete.
Web page downloads:
o
For pages requiring download times greater that 5
seconds, give the user
o
something to do while waiting.
o
Quickly present, at the top of the downloading
page, some text or links.
Blinking for Attention
Attract attention by flashing an indicator when an application is
inactive but must display a message to the user.
o
If a window, flash the title bar.
o
If minimized, flash its icon.
To provide an additional message indication, also provide an auditory
signal (one or two beeps).
o
Very useful if:
o The
window or icon is hidden.
o The
user’s attention is frequently directed away from the screen.
Display the message:
o
When the application is activated.
o
When requested by the user.
Use of Sound
Always use in conjunction with a visual indication.
Use no more than six different tones.
o
Ensure that people can discriminate among them.
Do not use:
o
Jingles or tunes.
o
Loud signals.
Use tones consistently.
o
Provide unique but similar tones for similar
situations.
Provide signal frequencies between 500 and 1,000 Hz.
Allow the user to adjust the volume or turn the sound off altogether.
Test the sounds with users over extended trial periods.
Use sounds sparingly because they:
o
Are annoying to many people, including other users
and nonusers in the vicinity.
o
Can easily be overused, increasing the possibility
that they will be ignored.
o
Are not reliable because:
§ Some
people are hard of hearing.
§ If they
are not heard, they leave no permanent record of having occurred.
§ The user
can turn them off
Sounds,
sometimes called earcons, are useful
for alerting the user:
o
To minor and obvious mistakes.
o
When something unexpected happens.
o
Where visual attention is directed away from the
screen and immediate attention is required.
o
When a long process is finished.
Privacy Policy, Terms and Conditions, DMCA Policy and Compliant
Copyright © 2018-2023 BrainKart.com; All Rights Reserved. Developed by Therithal info, Chennai.