Accessibility Timing Issues and Guidance.
Compiled by Gregg Vanderheiden
Based on discussion
at
This discussion relates to timing requirements placed on users. It covers constraints on the time users have to PERCEIVE information and/or to RESPOND.
Output is presented in Tabular and Linear form.
|
Generic Type |
Description |
Examples |
Guidance |
|
Realtime Event Based |
Timing constraints on user perception/response are the result of events happening in realtime – and not something that is created by or under the control of a software or web author. |
Ø Auctions Ø Discussions Ø Real world deadlines
|
1) Where possible, allow the user to construct their response in advance and inject it into the interaction with a single action (e.g. keystroke). 2) Allow user to freeze presentation of information (even if this means they will lose information presented in realtime until the release freeze).
Also good to a) Allow user to view flow at a reduced rate of flow (buffering realtime information). b) Allow user to restart flow (after freeze or slowdown) and view information at normal speed, but delayed c) Allow fast play of buffered information to catch up d) Allow jump ahead to catch up.
|
|
Timed Presentation |
Information is presented in a time based form. Time scale is determined by software or web author. |
Ø Warning Message Ø Moving text Ø Scrolling Text
|
1) Allow user to freeze presentation of information and restart where they froze presentation.
Also good to a) Allow user to view flow at a reduced rate of flow. b) Allow user to restart flow (after freeze or slowdown) and view information at normal speed, but delayed c) Also good to allow fast play of information to catch up d) Also good to allow jump ahead to catch up.
|
|
Timed Normed Tests |
Special case of timed tasks. Since the purpose of timing in tests varies and can effect (or not effect) test validity |
Ø Timed on-line tests |
Since the purpose of timing in tests varies and can effect (or not effect) test validity – No recommendations regarding timed tests which are compared against a norm are made here. |
|
Competitive Timed Tasks (other than tests). |
Task is timed and performance is compared against that of other people |
Ø Games Ø |
No Requirements [or do we want to require below]
Good to: Ø Allow user to change time scale of program (slow it down) to better match abilities of user though scores may be reported with notation of speed or reported in a separate listing.
|
|
Self –Referenced Timed Tasks and tests. |
Task is timed but time is only compared or reported against the user’s own times. |
Ø Games Ø Learning programs
|
1) Provide the user with a means to freeze action or display of information to allow more time for reading, reacting or entering input.
Also good to: Ø Allow user to change time scale of program (slow it down) to better match abilities of user
|
|
Auto Logout for Security or to prevent Financial Loss |
If there is no activity on any input devices for a predetermined period, the device or system will reset.
Reset is done to prevent use of system by another person if first user leaves or to allow release of product inventory if the person is not proceeding toward purchase in a timely manner. |
Ø ATMs Ø Websites involving financial transactions or personal information. Ø Timeout to return inventory to stock from a shopping cart
|
1) Ask user if they need more time when regular timeout is reached.
2) Provide additional time if user activates any input device within 10 seconds.
|
|
Regular Time Out |
If there is no activity on any input devices for a predetermined period, the device or system will reset. Security or Loss is not an issue. |
Ø Building directory
|
1) Ask user if they need more time when regular timeout is reached.
2) Provide additional time if user activates any input device within 10 seconds.
Also good to: Ø Allow user to adjust timeout Ø Allow user to turn off timeout
|
|
Busy Message |
Message is presented whose only purpose is to explain that the delay is normal and that the user is to just wait. |
Ø “One moment” Ø Please hold Ø Please wait |
Ø No timing accommodations are required to allow user to read. HOWEVER a) it is good to allow user to freeze message so that they can read it if they wish. b) If any information is presented that the author assumes the user will have time to read, then follow the guidance that is listed for “TIMED PRESENTATION”
|
|
Auto Redirect |
Person goes to a page – and the page forwards them automatically to another page. |
Ø Auctions
|
Ø If page has no information on it besides a “busy” phrase like “One moment while we transfer you” then no timing accommodations are required
Ø If page has information on it that the author intends for the user to see before they are transferred, then it should follow the guidance that is listed for “TIMED PRESENTATION”.
|
GENERIC TYPE
Realtime Event Based
Description
Timing constraints on user perception/response are the result of events happening in realtime – and not something that is created by or under the control of a software or web author.
Examples
Ø Auctions
Ø Discussions
Ø Real world deadlines
Guidance
1) Where possible, allow the user to construct their response in advance and inject it into the interaction with a single action (e.g. keystroke).
2) Allow user to freeze presentation of information (even if this means they will lose information presented in realtime until the release freeze).
Also good to
e) Allow user to view flow at a reduced rate of flow (buffering realtime information).
f) Allow user to restart flow (after freeze or slowdown) and view information at normal speed, but delayed
g) Allow fast play of buffered information to catch up
h) Allow jump ahead to catch up.
NEXT TYPE -----------------------------
Timed Presentation
Description
Information is presented in a time based form. Time scale is determined by software or web author.
Examples
Ø Warning Message
Ø Moving text
Ø Scrolling Text
Guidance
1) Allow user to freeze presentation of information and restart where they froze presentation.
Also good to
e) Allow user to view flow at a reduced rate of flow.
f) Allow user to restart flow (after freeze or slowdown) and view information at normal speed, but delayed
g) Also good to allow fast play of information to catch up
h) Also good to allow jump ahead to catch up.
NEXT TYPE -----------------------------
Timed Normed Tests
Description
Special case of timed tasks. Since the purpose of timing in tests varies and can effect (or not effect) test validity
Examples
Ø Timed on-line tests
Guidance
Since the purpose of timing in tests varies and can effect (or not effect) test validity – No recommendations regarding timed tests which are compared against a norm are made here.
NEXT TYPE -----------------------------
Competitive Timed Tasks (other than tests).
Description
Task is timed and performance is compared against that of other people
Examples
Ø Games
Ø
Guidance
No Requirements [or do we want to require below]
Good to:
Ø Allow user to change time scale of program (slow it down) to better match abilities of user though scores may be reported with notation of speed or reported in a separate listing.
NEXT TYPE -----------------------------
Self –Referenced Timed Tasks and tests.
Description
Task is timed but time is only compared or reported against the user’s own times.
Examples
Ø Games
Ø Learning programs
Guidance
1) Provide the user with a means to freeze action or display of information to allow more time for reading, reacting or entering input.
Also good to:
Ø Allow user to change time scale of program (slow it down) to better match abilities of user
NEXT TYPE -----------------------------
Auto Logout for Security or to prevent Financial Loss
Description
If there is no activity on any input devices for a predetermined period, the device or system will reset.
Reset is done to prevent use of system by another person if first user leaves or to allow release of product inventory if the person is not proceeding toward purchase in a timely manner.
Examples
Ø ATMs
Ø Websites involving financial transactions or personal information.
Ø Timeout to return inventory to stock from a shopping cart
Guidance
1) Ask user if they need more time when regular timeout is reached.
2) Provide additional time if user activates any input device within 10 seconds.
NEXT TYPE -----------------------------
Regular Time Out
Description
If there is no activity on any input devices for a predetermined period, the device or system will reset. Security or Loss is not an issue.
Examples
Ø Building directory
Guidance
1) Ask user if they need more time when regular timeout is reached.
2) Provide additional time if user activates any input device within 10 seconds.
Also good to:
Ø Allow user to adjust timeout
Ø Allow user to turn off timeout
NEXT TYPE -----------------------------
Busy Message
Description
Message is presented whose only purpose is to explain that the delay is normal and that the user is to just wait.
Examples
Ø “One moment”
Ø Please hold
Ø Please wait
Guidance
Ø No timing accommodations are required to allow user to read.
HOWEVER
c) it is good to allow user to freeze message so that they can read it if they wish.
d) If any information is presented that the author assumes the user will have time to read, then follow the guidance that is listed for “TIMED PRESENTATION”
NEXT TYPE -----------------------------
Auto Redirect
Description
Person goes to a page – and the page forwards them automatically to another page.
Examples
Ø Auctions
Guidance
Ø If page has no information on it besides a “busy” phrase like “One moment while we transfer you” then no timing accommodations are required
Ø If page has information on it that the author intends for the user to see before they are transferred, then it should follow the guidance that is listed for “TIMED PRESENTATION”.