Edit comment LC-1230 for Accessibility Guidelines Working Group

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Comment LC-1230: Comment Shortname:; Commenter: Masafumi Nakane <max@wide.ad.jp> on behalf of Keio University; Message-id:; Section of the document concerned:

or; Refinement of the section concerned:; Status:
assigned to; Type:; Resolution status:
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Commenter's response (URI):; Comment:
Is there any scientific fact that supports the figures given in this success criterion (10 times, 20 seconds) are sufficient? Unless these are scientifically proven values and are not likely to be changed in future, such values should not be included in a normative part of the document.

CLARIFICATION FROM Makoto Ueki: Nakane-san wanted to say that WG should explain the reason why the number is chosen more clearly in the documents. If WG doesn't do that, for example, a web developer only can say "WCAG 2.0 says so." to the client. He doesn't want the number to be removed.; Related issues: LC-1227,8,9
(space separated ids); WG Notes: [EDITORZ] one of a series of comments that asks for scientific fact for any number in guidelines. Discussed in the 20 July 2006 telecon: Resolution: refer LC-1230 back to editors to add some description of why the numbers are there http://www.w3.org/2006/07/20-wai-wcag-minutes.html CLARIFICATION FROM Makoto Ueki: Keep this issue open for the following reasons. Nakane-san wanted to say that WG should explain the reason why the number is chosen more clearly in the documents. If WG doesn't do that, for example, a web developer only can say "WCAG 2.0 says so." to the client. He doesn't want the number to be removed. Discussed in the 04 January 2007 telecon: resolution: LC 1230 accepted as amended http://www.w3.org/WAI/GL/2007/01/04-wai-wcag-minutes.html {accept partial} DONE add the following bullets to the end of the INTENT for 2.2.1 * 10 times the default was chosen based on clinical experience and other guidelines. For example, if 15 seconds is allowed for a user to respond and hit a switch, 150 seconds would be sufficient to allow almost all users to hit a switch even if they had trouble. * 20 seconds was also based on clinical experience and other guidelines. 20 seconds to hit 'any switch' is sufficient for almost all users including those with spasticity. Some would fail, but some would fail all lengths of time. A reasonable period for requesting more time is required since an arbitrarily long time can provide security risks to all users, including those with disabilities, for some applications. For example, with kiosks or terminals that are used for financial transactions, it is quite common for people to walk away without signing off. This leaves them vulnerable to those walking up behind them. Providing a long period of inactivity before asking, and then providing a long period for the person to indicate that they are present can leave terminals open for abuse. If there is no activity the system should ask if the user is there. It should then ask for an indication that a person is there ('hit any key') and then wait long enough for almost anyone to respond. For "hit any key" 20 seconds would meet this. If the person indicates that they are still present, the device should return the user to the exact condition that existed before it asked the question. XML updated 19 January 2007.; Resolution: It is not clear what you mean by scientific fact. There is no number that is sufficient for all users. For some individuals, these values would not be enough. For others, they are. Still others do not need values this high. Removal of the numbers would make the success criterion untestable, so that is not an option. In the opinion of those on the working group and those consulted who work with populations with timing problems, these figures are sufficient to cover most users and the numbers harmonize with other accessibility standards efforts. The following text has been added to the "how to meet" document for 2.2.1 to provide more information on the numbers used. * 10 times the default was chosen based on clinical experience and other guidelines. For example, if 15 seconds is allowed for a user to respond and hit a switch, 150 seconds would be sufficient to allow almost all users to hit a switch even if they had trouble. * 20 seconds was also based on clinical experience and other guidelines. 20 seconds to hit 'any switch' is sufficient for almost all users including those with spasticity. Some would fail, but some would fail all lengths of time. A reasonable period for requesting more time is required since an arbitrarily long time can provide security risks to all users, including those with disabilities, for some applications. For example, with kiosks or terminals that are used for financial transactions, it is quite common for people to walk away without signing off. This leaves them vulnerable to those walking up behind them. Providing a long period of inactivity before asking, and then providing a long period for the person to indicate that they are present can leave terminals open for abuse. If there is no activity the system should ask if the user is there. It should then ask for an indication that a person is there ('hit any key') and then wait long enough for almost anyone to respond. For "hit any key" 20 seconds would meet this. If the person indicates that they are still present, the device should return the user to the exact condition that existed before it asked the question.; (Please make sure the resolution is adapted for public consumption)