DRAFT NOTE: Web Content Accessibility Guidelines Impact Matrix

This document:: http://www.w3.org/WAI/GL/NOTE-WCAG-impact-matrix-19990810
Latest version:: http://www.w3.org/WAI/GL/WCAG-impact-matrix
Editors:: Wendy Chisholm, Trace R & D Center, University of Wisconsin -- Madison
Gregg Vanderheiden, Trace R & D Center, University of Wisconsin -- Madison
Ian Jacobs, W3C

Abstract

This document examines the impact of each checkpoint listed in the Web Content Accessibility Guidelines 1.0. For each checkpoint, we list the disabilities and technologies most affected.

Status of this document

This is a Draft W3C NOTE for review by the Web Content Guidelines Working Group. It has not been approved for publication as a W3C Note.

A list of current W3C Recommendations and other technical documents can be found at http://www.w3.org/TR.

This document has been produced as part of the Web Accessibility Initiative. The goal of the Web Content Guidelines Working Group is discussed in the Working Group charter.

Please send comments about this document to w3c-wai-gl@w3.org.

Summary of Disabilities Considered
Tabular Presentation
List Presentation

Summary of Disabilities Considered

The following sections list and summarize disabilities considered in this matrix.

Note. The information in this section should be part of a separate W3C Note.

Visual Disabilities

All visual information must be available in text or sound (may be produced by client-side text-to-speech synthesizers), no mouse required, distinguishing information should not be color specific.

Quick Tests: Don't load graphics in graphical browsers such as Microsoft Internet Explorer or Netscape's Communicator. (include directions for how to turn off graphics?) Print pages on black and white printers to see how usable the page is without color. Read the page over the phone to someone to determine the usability of text equivalents.

Blindness

In the United States, blindness is defined as,

visual acuity (sharpness of vision) of 20/200 or worse in the better eye, after correction, or when the field of vision is less than 20 degrees in the better eye, after correction.

Low vision

A variety of impairments to the eyes or neural functions associated with seeing are called "low vision." They include the following. We have separated color deficit into its own category.

lowered central acuity, including dimness of vision, haziness, film over the eye, foggy vision, myopia (near-sightedness), and hyperopia (far-sightedness).
distortion of vision, where objects may appear to bulge, curve, or "look funny"
Spots or floaters before the eyes, including stationary spots that move with the eye.
Field-of-vision defects, including no vision in specified regions of visual field, or "tunnel" vision.
Abnormal sensitivity to light
Night blindness
Oscillopsia, where the world seems to be moving or jumping around (also called "nystagmus.")

Color deficit or distortions

Colors may not be detected or may not be distinguishable.

Technologies

Screen reader, screen magnifier, dynamic braille display

Hearing disabilities

Deafness

The United States legal definition is, "Sound must reach at least 90 decibels to be heard at all and amplified speech cannot be understood."

Hard of hearing

Less severely impaired than deafness.

Cognitive, learning, and language disabilities

In general, there are several sub-categories of cognitive and learning disabilities:

impairments of intelligence or thinking - developmental delay (mental retardation) and dementia
impairments of memory - forgetfulness, amnesia, memory illusions
other intellectual impairments
aphasia - inability to interpret and/or formulate language symbols as a result of brain damage. May affect expressive or receptive aspects of language and communication.
learning disabilities - four categories: spoken language, written language, arithmetic, reasoning.

For the purposes of this document, we will use the following categories: cognitive impairments (developmental delay and dementia), memory impairments, language disabilities, and learning disabilities (spoken language, written language - non-readers/dyslexia, arithmetic, reasoning).

Physical disabilities

Physical disabilities are categorized according to neuromuscular impairments and skeletal impairments as described below.

To summarize the groups in physical disabilities we have: paralysis, weakness, difficult voluntary movement, problems with coordination, involuntary movements (tremor), limited range of movement, small, malformed, or missing limbs, abnormal trunk size.

Neuromuscular impairments

Neuromuscular impairments are impairments to nerves, brain, and muscles and include most speech impairments). They may be divided into the following categories:

paralysis,
weakness,
interference with control (spasticity - voluntary movement is difficult due to contracted muscles),
ataxia ("problems in motor programming and coordination"),
athetosis & chorea (involuntary movements such as tremor).

Skeletal impairments

Skeletal impairments are impairments of bones, or joints, and missing limbs. This includes:

joint movement limitations,
small or malformed limbs,
missing limbs,
abnormal trunk size.

Photo sensitive epilepsy

Some people have seizures triggered by flickering or flashing in the 4 to 59 flashes per second (Hertz) range with a peak sensitivity at 20 flashes per second as well as quick changes from dark to light (like strobe lights).

Tabular presentation

Each checkpoint links to its definition in the Web Content Accessibility Guidelines 1.0.

Checkpoint	Disabilities	Input Technologies	Output Technologies
1.1	all	braille, keyboard, voice	braille, small/magnified screen, speech, visual
1.2	blind, low vision, physical, cognitive/learning	braille, keyboard, voice	all
1.3	blind, low vision, color deficit, cognitive/learning, language	none	speech, audio
1.4	blind, low vision, deaf, hard of hearing, cognitive/learning	none	audio, visual, speech, braille
1.5	blind, low vision, physical, cognitive/learning	braille, keyboard, voice	all
2.1	color deficit	none	visual
2.2	color deficit	none	visual
3.1	blind, low vision, color deficit, cognitive/learning, epilepsy	none	braille, speech, small/magnified screen, visual
3.2	all	all	all
3.3	all	none	all
3.4	all	none	all
3.5	all	all	all
3.6	all	none	all
3.7	all	none	all
4.1	blind, low vision, cognitive/learning	voice	speech, braille
4.2	cognitive/learning, blind, low vision, deaf	none	speech, visual, braille
4.3	blind, low vision, cognitive/learning	voice	speech, braille
5.1	all	keyboard, braille	all
5.2	all	keyboard, braille	all
5.3	blind, low vision	none	speech, braille, small/magnified screen
5.4	blind, low vision	none	speech, braille, small/magnified screen
5.5	all	none	all
5.6	blind, low vision, cognitive/learning	voice	speech, braille
6.1	all	none	all
6.2	all	none	none
6.3	all	all	all
6.4	all	all	none
6.5	all	all	all
7.1	epilepsy	none	visual
7.2	epilepsy, cognitive/learning	none	visual, speech, braille
7.3	cognitive/learning, physical, blind, low vision, epilepsy	all	all
7.4	blind, low vision, cognitive/learning, physical, epilepsy	none	all
7.5	blind, low vision, cognitive/learning, physical, epilepsy	none	all
8.1	all	all	all
9.1	blind, low vision	braille, keyboard, voice	speech, braille, small/magnified screen
9.2	all	all	all
9.3	blind, low vision, deaf, hard of hearing, physical, speech	all	none
9.4	blind, low vision, cognitive/learning, physical	braille, keyboard, voice	none
9.5	blind, low vision, cognitive/learning, physical, speech	braille, keyboard, voice	none
10.1	blind, low vision, cognitive/learning, physical	braille, keyboard, voice	all
10.2	blind, low vision, cognitive/learning	none	speech, visual, small/magnified screen
10.3	blind, low vision	none	speech
10.4	blind, low vision, cognitive/learning	none	speech, braille
10.5	blind, low vision	none	speech, braille
11.1	all	all	all
11.2	all	all	all
11.3	all	all	all
11.4	all	all	all
12.1	blind, low vision, cognitive/learning	braille	speech, braille, small/magnified screen
12.2	blind, low vision, cognitive/learning	braille	speech, braille, small/magnified screen
12.3	blind, low vision, cognitive/learning	braille, keyboard	all
12.4	blind, low vision, cognitive/learning, physical	none	all
13.1	all	all	all
13.2	all	all	all
13.3	all	all	all
13.4	all	all	all
13.5	all	all	all
13.6	blind, low vision, cognitive/learning, physical	braille, keyboard	audio, braille, speech
13.7	all	none	none
13.8	all	braille, keyboard, voice	audio, braille, small/magnified screen, speech
13.9	all	all	all
13.10	blind, low vision	braille, keyboard	audio, braille, speech
14.1	all	all	all
14.2	all	none	audio, small/magnified screen, speech, visual
14.3	cognitive/learning, blind, low vision	all	all

List presentation