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Re: My comments on WCAG 2.0 proposed draft

From: Doyle Burnett <dburnett@sesa.org>
Date: Tue, 09 Dec 2003 11:51:15 -0900
To: "Arditi, Aries (by way of Wendy A Chisholm <wendy@w3.org>)" <aarditi@lighthouse.org>, W3C Web Content <w3c-wai-gl@w3.org>
Message-ID: <BBFB67B3.16FE%dburnett@sesa.org>

Thanks For Your Re-Post, Aries -

As I am one of a number of us working on a "re-look" at guideline 1.6 within
the draft of WCAG 2.0, I would like to follow-up with some of what you had
to say.  First, for me alone, thank you for the input - I am sure others
appreciated your comments.

Given my own personal experiences with color deficiency issues, I agree that
an algorithm is probably not going to solve the issue of helping authors
develop 100% readable content.   With regard to the "vastness" of issues
concerning color/contrast: brightness, hue saturation, environmental
conditions, monitor types and their differences, individual user
differences/preferences, etc, etc, etc - it is unlikely that a formula can
easily solve the issues.

Are you suggesting that 1.6 and 1.7 be combined as a single guideline?  I
could be wrong and by no means speak for the larger group, but I believe the
20 dB (4xlouder) came from an earlier post with regard to what the audio
company Shure (Shure microphone fame) recommends as the
background/foreground noise ratio.

The American Speech and Hearing Association also has standard signal to
noise ratios that apply to classroom environment - please see:

These ratios are for listeners with normal hearing.  Individuals with
hearing loss would need to have determined their individual "hearing loss
threshold" and have the speech increased to the +15 to 20 dB levels to
discriminate speech over background noise.  This seems close to the 20 dB
that WCAG came up with and possibly this would be a good source to reference
but it does NOT speak specifically to sound from a computer.  However, it
seems (to me personally) a good place to start and something to be able to
refer back to.  

My thoughts -

Doyle Burnett

Doyle Burnett
Education and Training Specialist
Multiple Disabilities Program
Special Education Service Agency

On 12/9/03 10:13 AM, "Arditi, Aries   (by way of Wendy A Chisholm
<wendy@w3.org>)" <aarditi@lighthouse.org> wrote:

> Hi all,
> Wendy Chisholm and Judy Brewer asked me to comment on this months ago, and
> I posted it to the site they asked me to post it at.  Recently, someone
> more savvy in the functioning of the WAI lists informed me that the list is
> totally ignored.  So here, I repost it, in the hopes that it might be
> helpful to someone, somewhere, some day....
> Aries Arditi
> Senior Fellow in Vision Science
> Lighthouse International
> Original Post:
> With respect to the June 24 WCAG 2.0 draft, I have a number of comments,
> detailed below.  First, however, I would like to congratulate the authors
> for taking on such a difficult task.  In particular, I'm delighted that the
> group is intending to broaden the scope of the guidelines to address a
> broader set of technologies.  To the extent that this broadening succeeds,
> its influence can go well beyond that of web content and authoring, and
> potentially guide the efforts of developers of assistive technology as well.
> Having said that, I believe also that the guidelines are in general less
> comprehensible (indeed, less accessible!) to the intended readership than
> were the version 1.0 guidelines, and that the lack of comprehensibility
> stems from the very abstraction of principles that was necessary for
> broadening to other technologies.  I believe these problems can be addressed
> and alleviated through the planned technology-specific checklists,
> especially if the checkpoints in the WCAG are cross referenced to technology
> specific guidelines. Apart from a few exceptions, I don't believe, however,
> that making the guidelines significantly easier to understand can be
> accomplished by simple rewriting.  Like a mathematics text in which axioms
> and theorems provide the foundation, and examples and problems the practical
> understanding, this may be a necessarily abstract document.
> The conformance structure of Core and Extended is fine, both easy to
> understand and potentially effective, provided more objective and
> quantitative methods of evaluating specific conformance to checkpoints can
> be developed.  But conformance to specific checkpoints is best evaluated in
> the context of specific technologies, where specific items are less open to
> braod interpretation.  Without technology specific checkpoints, I would
> imagine that squabbling and bickering over conformance will increase, and
> with more latitude to interpret the guidelines as they see fit, developers
> could claim more for less actual conformance.  So I would favor keeping the
> general structure of the draft as a kind of umbrella document, but
> instantiate the conformance checkpoints with technology-specific
> checkpoints.  Since the planned technology-specific checklists were not
> included in this draft, it's difficult to evaluate the conformance
> structure.  However, in theory, the structure seems fine to me.
> Developers at my organization do use the 1.0 WCAG, but much of their use is
> indirect---via automated tools to evaluate conformance.  Because web sites
> can be huge and dynamic, reliance on such tools is at least partially
> inevitable.  However, to the extent that the current document is even less
> specific than v1.0, I would see migration being difficult. Without
> technology-specific checklists, it is easy to imagine developers of
> evaluation and repair tools with widely disparate views of what constitutes
> conformance.  Again, I would prefer to view this draft as an umbrella
> document with more specifics to be incorporated as an essential component of
> the 2.0 WCAG recommendation.
> Here are some other specific comments, nearly all pertaining to Guidelines 1
> and 2:
> 1. I didn't understand the designation of examples and benefits as
> "non-normative"  or "informative."  Are these terms lingo, or am I just
> being thick (or both)?
> 2. Overview of Design Principles, last para before Note:
> This would better read, "Accessible web content can benefit people with as
> well as without disabilities." Accessible web content does not ALWAYS
> benefit people other than the disabled. High levels of magnification, for
> example, which can make things more accessible to people with low vision,
> can make documents more difficult to navigate.
> Delete next 2 sentences, which are superfluous since examples of accessible
> web content benefiting others is subsequently given (and giving wheelchair
> examples to the reader is tiresome---readers of the WCAG can, nearly 14
> years after the ADA, be assumed to understand general things about
> disabilities without being prompted to conjure up images of wheelchairs).
> 3. User needs, first bullet:
> Change "via sound" to "visually."
> 4. Definitions for checkpoint 1.1: text equivalent
> This is not a definition.  I would first define "text" as code representing
> written language, that is a one-to-one mapping of alphabetic and numeric
> symbols.  Then define "text-equivalent" as text that serves to communicate
> substantially equivalent content as another representation such as an image.
> 5. Benefits of checkpoint 1.1, first bullet:
> add ", or otherwise transformed to different presentation format (e.g. font,
> text size)
> 6. Checkpoint 1.5
> I believe that the benefit of adding structure to the document is that it
> allows assistive technologies more information about the document in order
> to tailor its presentation to the user's capabilities.  This checkpoint, as
> written, however, seems to focus on how document elements are rendered.  For
> example, the (sole) required success criterion refers to visual appearance
> or auditory characteristic.  The examples also are about how to render.
> That's not a WCAG issue, in my view.
> Also, who (or what) could judge whether structure "has been made perceivable
> to more people..."?  Compared to what? This is way too vague.
> 7. Editorial Note (22 May 2003) regarding "additional items in 4/29 draft
> Yes, in my opinion, these should be moved to techniques.
> 8.  Checkpoint 1.6
> This is very vaguely worded.  I would propose instead the following
> language:  "Where possible, use layered designs to allow selective
> presentation or blanking of visual or auditory elements, comprising, for
> example, foreground and background content."
> The sole success criterion for 1.6 is in terms only of visually imagery.  I
> would refer to layered auditory images, such as background music with a
> voice-over, to allow hearing-impaired user to remove the background music
> for greater clarity.
> Under best practice for 1.6 #1 and #2, what does "easily readable" mean?
> And to whom? This is not quantifiable.
> Also, who came up with the 20 dB (or 4 X louder) foreground/background audio
> figure?  Are there any data to back this up as being sufficient?
> It's true that there are no effective tests for visibility or readability
> that do not rely on standard human observers in terms of color or color
> contrast (the claims of some notwitstanding). The reasons for this include
> the fact that display devices and hardware used to drive them vary widely in
> peak luminance, color gamut, and linearity; viewing conditions of observers
> vary widely (ambient room lighting, presence of reflections from nearby
> windows, etc.); readability and visual discriminability also depend
> critically on the kinds of stimuli used.  A very low contrast text in a huge
> font may be as or more readable than a smaller font in very high contrast.
> Typography and image characteristics also go into the mix of important
> factors.  And let us not leave out the enormous variability in visual
> capacity of the visually-impaired population, some of whom will settle for
> no less than the blackest black against the whitest white. The long and
> short of it is that we simply do not have in the foreseeable future a good
> way to evaluate objectively things like accessibility of text contrast
> and/or color.  This is thus an issue in which, I believe, the best we can do
> (and thus the most we should do) is to suggest principles to follow to
> enhance accessibility.
> 9. Examples of checkpoint 1.6 first bullet:
> What are the "standard foreground/background contrast requirements"? If
> there are any, please clarify (and cite).
> 10. Required success criteria for checkpoint 2.2 #1:
> I would add the following bullet: "* or the user can control the
> presentation by eliciting phases sequentially via keystrokes."
> 11. Checkpoint 2.3
> I would be very surprised if anyone could devise a substantive and effective
> test for flicker in machine readable format.  Here are some thought
> experiments:
> Consider a single pixel flickering in the 3-49Hz range on your screen right
> now.  Do you think you could detect it?  If so, do you think it could
> possibly cause a seizure in someone with photosensitive epilepsy?  You do?
> How about if that single pixel flickered by changing its intensity 1/256? or
> 1/(256^3)?
> Still think so?
> How many phases (i.e. alternations) of light and dark constitute flicker in
> the 3-49 Hz range? What if I present a black dot for 1.5 seconds, then
> replace it by a white dot for 1.5 seconds?  Would you call that 3 Hz
> flicker?  In other words, how many "cycles" of the pattern do you require
> before you call it flicker?
> Here's a third: Mathematically the sum of leftward moving and rightword
> sinusoidal gratings is equal to a single stationary sinusoidal grating whose
> bars reverse in contrast.  Any single point in that pattern will flicker. Do
> we call that flicker or moving gratings?  Were we to analyze many moving
> patterns we would find that we could describe them mathematically in terms
> of flickering components. What if we have a video taken from a moving car or
> train that passes by a picket fence.  Will not there be some flicker in that
> video? Shall we ban all animations in the WCAG?
> It is likely that scientists will some day be able to better zero in on the
> specific visual causes of photosensitive epileptic seizures; presumably high
> contrast large field flicker poses a greater risk than do low contrast
> flickering single pixels.
> Until we know more, or until qualified experts on this condition weigh in,
> or credible scientific evidence is presented that better specifies the
> parameters of the flicker, I believe this checkpoint should be deleted.
> Thank you for the opportunity to comment on this draft.
> Aries Arditi, Ph.D.
> Senior Fellow in Vision Science
> Arlene R. Gordon Research Institute
> Lighthouse International
> 111 East 59th Street
> New York, NY 10022
> Tel: +1 212 821 9500 (direct)
> Fax: +1 212 751 9667
> <http://www.lighthouse.org/research_staff_arditi.htm>http://www.lighthouse.org
> /research_staff_arditi.htm
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Received on Tuesday, 9 December 2003 15:53:38 UTC

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