[Archived] Shared Web Experiences: Barriers Common to Mobile Device Users and People with Disabilities | Web Accessibility Initi

[Archived] Shared Web Experiences: Barriers Common to Mobile Device Users and People with Disabilities | Web Accessibility Initiative (WAI) | W3C
If you want current information on
mobile accessibility
— that is, people with disabilities using content on mobile devices, see
This page is archived. We do not plan to update it. It was developed in 2008. Much of the information is still relevant today. It is useful for understanding that:
Many of the issues around designing for mobile devices are addressed by designing for people with disabilities.
When you address accessibility, you improve the mobile experience. This can help in presenting your business case for accessibility.
This page describes many of the barriers that people with disabilities
and people using mobile devices experience when interacting with web
content, including web applications. It shows how these
barriers are
similarly addressed in
W3C
’s Web Content
Accessibility Guidelines (WCAG), Mobile Web Best Practices, and Mobile
Web Application Best Practices.
Background
People with disabilities using computers have similar interaction
limitations as people without disabilities who are using mobile devices.
Both experience similar barriers when interacting with websites and web
applications. There is also significant overlap between the design
solutions for both. For more background, see:
An introduction to the overlap between W3C guidelines for
accessibility and best practices for mobile devices:
Web Content
Accessibility and Mobile Web: Making a Website Accessible Both for
People with Disabilities and for Mobile
Devices
Introduction to Web
How People with Disabilities Use the
Web
A comprehensive comparison between MWBP and WCAG is provided in
Relationship between Mobile Web Best Practices (MWBP) and Web Content
Accessibility Guidelines (WCAG)
Introduction
The barriers on this page are grouped under four principles:
perceivable, operable, understandable and robust. These principles lay
the foundation necessary for anyone to access and use web content, as
described in
Understanding the Four Principles of
section of Introduction to Understanding WCAG 2.0. (Mobile devices vary
widely and not all the barriers are present on all models.)
This page includes links to some relevant solutions in:
Web Content Accessibility Guidelines (WCAG)
2.0
Web Content Accessibility Guidelines (WCAG)
1.0
Note:
W3C WAI recommends
using WCAG 2.0
, instead
of WCAG 1.0.
Mobile Web Best Practices 1.0
Mobile Web Application Best Practices
The information below is also available in
tabular
format
Contents
Perceivable
Information conveyed solely with color
Large pages or large images
Multimedia with no captions
Audio-only prompts (beeps) for important information (warnings,
errors)
Non-text objects (images, sound, video) with no text
alternative
Text entry
Content formatted using tables or CSS, and reading order not
correct when linearized (for example when CSS or tables not
rendered)
Information conveyed only using CSS (visual
formatting)
Operable
Mouse required for interaction and navigation
Scripting required to operate content
Special plugin required
Missing or inappropriate page title
Inconsistency between focus (tab) order and logical document
content sequence
Non descriptive link label
Understandable
Long words, long and complex sentences, jargon
Content spawning new windows without warning user
Blinking, moving, scrolling or auto-updating content
Robust
Invalid or unsupported markup
Scripting required to generate content
Perceivable
Information and user interface components must be presentable to users
in ways they can perceive.
Experiences discussed below are also available in
tabular
format
User perceives color incorrectly or not at all, and so misses or
misunderstands information or makes mistakes.
Disabilities Context:
User who is blind or colorblind perceives
color incorrectly or not at all.
WCAG 2.0 success criteria:
1.4.1 Use of
Color
1.3.1 Info and
Relationships
1.4.3 Contrast
(Minimum)
and
1.4.6 Contrast
(Enhanced)
WCAG 1.0 checkpoint:
2.1
and
2.2
Mobile Context:
Many screens have limited color palette and color
difference is not presented. Device is used in poor lighting (for
example, outdoors), so colors are not clearly perceived.
MWBP 1.0 Best Practice:
USE_OF_COLOR
and
COLOR_CONTRAST
User only sees small areas at a time, is unable to relate different
areas of a page, and so becomes disoriented or has to scroll
excessively. Additionally, user cannot access picture details because
the picture is shrunk.
Disabilities Context:
User with restricted field of vision or using
screen magnifier gets only small part of page or image at a time.
WCAG 2.0 Success Criteria:
1.4.8 Visual
Presentation
WCAG 1.0 checkpoint:
12.3
Mobile Context:
Mobile device has small screen (viewport).
MWBP 1.0 Best Practice:
PAGE_SIZE_USABLE
and
SCROLLING
User misses auditory information.
Disabilities Context:
User who is deaf or hard of hearing cannot
hear.
WCAG 2.0 Success Criteria:
1.2.2 Captions
(Prerecorded)
1.2.4 Captions
(Live)
and
1.2.8 Media Alternative
(Prerecorded)
WCAG 1.0 checkpoint:
1.1
and
1.4
Mobile Context:
Mobile users often turn off sound in public places
(trains, hotel lobbies); or often cannot hear in noisy places (streets,
nightclubs).
MWBP 1.0 Best Practice:
NON-TEXT-ALTERNATIVES
User cannot operate or interact correctly with content, misses prompts,
makes mistakes.
Disabilities Context:
User who is deaf or hard of hearing cannot
perceive content.
WCAG 2.0 Success Criteria:
1.2.1 Audio-only and Video-only
(Prerecorded)
WCAG 1.0 checkpoint:
1.1
and
1.4
Mobile Context:
Users often cannot hear in noisy (street, nightclub)
or in public places (trains, hotel lobbies).
MWBP 1.0 Best Practice:
NON_TEXT_ALTERNATIVES
User cannot perceive important information or loses information due to
lack of alternative.
Disabilities Context:
User who is blind cannot perceive content that
include non-text objects. Furthermore, information not available to user
whose browser, assistive technology, other user agent doesn’t support
object.
WCAG 2.0 Success Criteria:
1.1.1 Non-text
content
WCAG 1.0 checkpoint:
1.1
Mobile Context:
User can be billed for download volume so images
might be turned off to save costs. Some mobile user agents have limited
support for non-text objects so user loses information. Some user agents
also shrunk images in size to fit the device’s screen which can make
images meaningless.
MWBP 1.0 Best Practice:
NON_TEXT_ALTERNATIVES
and
OBJECTS_OR_SCRIPT
User has difficulty entering text so text is entered incorrectly or
mistakes are made.
Disabilities Context:
User with motor disability (for example,
partial paralysis, hand tremor, lack of sensitivity, coordination) has
difficulty entering information.
WCAG 2.0 Guideline:
3.3 Input Assistance: Help users avoid and
correct mistakes
Mobile Context:
Device has small keypad which has limited
functionality compared to a full keyboard, or is held in an unsteady
hand.
MWBP 1.0 Best Practice:
MINIMIZE_KEYSTROKES
PROVIDE_DEFAULTS
and
DEFAULT_INPUT_MODE
User cannot understand the content correctly when it’s presented in a
linear order.
Disabilities Context:
User who is blind reads content in document
tree order.
WCAG 2.0 Success Criteria:
1.3.2 Meaningful
Sequence
WCAG 1.0 checkpoint:
5.3
and
5.4
Mobile Context:
Meaning of content can be changed because of
reformatting or restructuring in adaptation process.
MWBP 1.0 Best Practice:
TABLES_LAYOUT
TABLES_NESTED
and
TABLES_ALTERNATIVES
User is unable to access information encoded in visual formatting or in
CSS.
Disabilities Context:
User who is blind doesn’t perceive visual
formatting effects.
WCAG 2.0 Success Criteria:
1.3.1 Info and
relationship
WCAG 1.0 checkpoint:
6.1
Mobile Context:
Often no or limited CSS support or diverging CSS
support by mobile browser.
MWBP 1.0 Best Practice:
STYLE_SHEETS_SUPPORT
Operable
User interface components and navigation must be operable.
Experiences discussed below are also available in
tabular
format
User is unable to navigate all content, or wastes time moving through
numerous links.
Disabilities Context:
Some users with a motor disability cannot use
a mouse. Users who are blind also do not use the mouse.
WCAG 2.0 Guideline:
2.1 Keyboard
Accessible
WCAG 1.0 checkpoint:
6.3
6.4
6.5
and
8.1
Mobile Context:
Device has no mouse, only alphanumeric keypad or
joystick.
MWBP 1.0 Best Practice:
OBJECTS_OR_SCRIPT
IMAGE_MAPS
NAVBAR
BALANCE
and
ACCESS_KEYS
MWABP Best Practice:
3.5.3 Design for Multiple Interaction
Methods
User cannot operate the content so loses some information.
Disabilities Context:
User’s assistive technology or browser doesn’t
support scripting.
WCAG 2.0 Conformance Requirement:
Conformance Requirement 4: Only
Accessibility-Supported Ways of Using
Technologies
and
Conformance Requirement 5:
Non-Interference
WCAG 1.0 checkpoint:
6.3
6.4
6.5
and
8.1
Mobile Context:
Scripting turned off or not supported.
MWBP 1.0 Best Practice:
OBJECTS_OR_SCRIPT
MWABP Best Practice:
3.6.4 Support a non-JavaScript Variant if
Appropriate
User can not perceive content or can not operate interface.
Disabilities Context:
Plugin turned off, or not installed, or not
compatible with assistive technology. Plugin not operable with preferred
input device.
WCAG 2.0 Success Criteria:
2.1.1
Keyboard
and
2.1.3 Keyboard (No
Exception)
WCAG 1.0 checkpoint:
11.1
Mobile Context:
Plugin turned off, or not installed, or not
available; not compatible with input device (for example, requires
mouse).
MWBP 1.0 Best Practice:
OBJECTS_OR_SCRIPT
User cannot easily scan to get an overview because of missing,
inappropriate, or long page title.
Disabilities Context:
User who is blind typically uses a screen
reader feature to get a list of the currently open windows, by window
title. Therefore, if the page title is long, inappropriate or missing,
user cannot perceive the content.
WCAG 2.0 Success Criteria:
2.4.2 Page
titled
WCAG 1.0 checkpoint:
13.2
Mobile Context:
Page title truncated to fit narrow viewport of
mobile device.
MWBP 1.0 Best Practice:
PAGE_TITLE
User is unable to navigate content in logical sequence, becomes
disoriented.
Disabilities Context:
User with motor disability uses keyboard for
navigation not mouse. User who is blind also often use tab navigation to
move from one element to another.
WCAG 2.0 Success Criteria:
2.4.3 Focus
order
WCAG 1.0 checkpoint:
9.4
Mobile Context:
Mobile devices may not have a pointing device so the
user may have to navigate elements serially.
MWBP 1.0 Best Practice:
TAB_ORDER
User cannot determine to follow or not to follow a link because the link
label is not descriptive enough.
Disabilities Context:
User can not determine purpose of a link when
read out of context. User who is blind often accesses a list of links on
a page without the context around them.
WCAG 2.0 Success Criteria:
2.4.4 Link Purpose (In
Context)
and
2.4.4 Link Purpose (Link
only)
WCAG 1.0 checkpoint:
13.1
Mobile Context:
User can not determine purpose of link.
MWBP 1.0 Best Practice:
LINK_TARGET_ID
and
LINK_TARGET_FORMAT
Understandable
Information and the operation of user interface must be understandable.
Experiences discussed below are also available in
tabular
format
User has difficulty understanding information.
Disabilities Context:
Users with some types of cognitive
disabilities have difficulty processing information. Users who are deaf
and whose native language is sign, have difficulty processing complex
written language.
WCAG 2.0 Success Criteria:
3.1.5 Reading
level
WCAG 1.0 checkpoint:
14.1
Mobile Context:
Text is displayed in small font, and user is often
distracted by ambient conditions (background noise, conversations,
moving objects in field of vision).
MWBP 1.0 Best Practice:
SUITABLE
and
CLARITY
User becomes disoriented among windows; back button doesn’t work. User
closes window, not realizing it is last in stack, closing browser
instance.
Disabilities Context:
User with low vision, or restricted field of
vision, or blindness, or cognitive disabilities doesn’t realize active
window is new.
WCAG 2.0 Success Criteria:
3.1.2 On
focus
3.2.2 On
input
and
3.2.5 Change on
request
WCAG 1.0 checkpoint:
10.1
Mobile Context:
Single window interface. Multiple stacked windows on
small screen hide each other.
MWBP 1.0 Best Practice:
POP_UPS
User has difficulty reading and comprehending content.
Disabilities Context:
People with reading disabilities, cognitive
limitations, and learning disabilities do not have sufficient time to
read or comprehend information.
WCAG 2.0 Success Criteria:
2.2.2 Pause, Stop,
Hide
and
3.2.5
Change on
request
WCAG 1.0 checkpoint:
7.4
and
7.5
Mobile Context:
Reduced size of mobile viewport or poor ambient
lighting makes it difficult to see content. Auto-refreshed pages may
also have cost implications if they are left open or put unnoticed into
the background.
MWBP 1.0 Best Practice:
AUTO_REFRESH
and
IMAGES_SPECIFY_SIZE
Robust
Content must be robust enough that it can be interpreted reliably by a
wide variety of user agents, including assistive technologies.
Experiences discussed below are also available in
tabular
format
User cannot access the content because browser or adaptation system
chokes on markup or rejects or garbles it.
Disabilities Context:
User’s assistive technology or browser cannot
handle markup.
WCAG 2.0 Success Criteria:
4.1.1
Parsing
WCAG 1.0 checkpoint:
3.2
11.1
and
11.2
Mobile Context:
Some older mobile browsers do not display content
with invalid markup.
MWBP 1.0 Best Practice:
VALID_MARKUP
User cannot access the content so loses some information because
scripting is not supported by the user agent.
Disabilities Context:
User’s assistive technology or browser doesn’t
support scripting.
WCAG 2.0 Success Criteria:
Understanding Guideline
4.1
WCAG 1.0 checkpoint:
6.3
Mobile Context:
Scripting turned off or not supported.
MWBP 1.0 Best Practice:
OBJECTS_OR_SCRIPT
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