Step-9 Provide Effective Feedback and Guidance and Assistance
Topics covered n n n Acceptable response times Dealing with time delays Blinking for attention The use of sound Review of guidance & assistance
Page Downloading n Maximum downloading time should be about 10 seconds - Use incremental or progressive image presentation n Images should be - n n Small Lean (low bit depth, resolution, use of fewer colors, etc. ) Reusable Contain pixel height & width dimensions in a tag Use thumbnail images to preview larger images Use simple background images
Dealing with Time Delays n n - n - - Button click acknowledgement Waits of up to 10 sec Present a “busy” signal until complete (ex: hourglass) Waits of 10 sec to 1 min Rolling barber’s pole or other large animated object Additionally, progress indicator, % complete msg, or elapsed time msg Waits over 1 min Present an estimate of the length of the wait Progress, %, time When a long operation is completed, present an acknowledgement - significantly changed screen appearance - auditory tone If an operation is very time-consuming - break it into subtasks & provide progress indicator for each subtask - allow users to start a new activity while waiting
Dealing with Time Delays (cont) n n n - - Long, invisible operations A message and an auditory tone Progress indicator Dynamically fill the bar Fill it with a color or shade of gray Left to right or bottom to top Percent complete message Useful if progress indicator takes too long to update Elapsed time message Useful if length is not known in advance A particular part of the operation will take an unusually long time to complete Web page downloads If >5 sec, give the user something to do while waiting - quickly present, at the top of the downloading page, an image, text, or links Advise of long download times
Blinking for Attention n - n - Attract attention by flashing an indicator when an application is inactive but must display a message to the user If a window, flash the title bar If minimized, flash its icon To provide an additional message indication, also provide an auditory signal (one or two beeps) Very useful if - The window or icon is hidden - The user’s attention is frequently directed away from the screen Display the message When the application is activated When requested by the user
Use of Sound n n n In conjunction with a visual indication <=6 different tones Do not use jingles or loud signals Consistency Configuration Use sounds sparingly
Guidance and Assistance See p. 603
Preventing Errors n MAXIM Everyone makes mistakes, so every mistake should be fixable.
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