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Emploi et formation : NTIC et accessibilité

How Assistive Software Supports Web Accessibility

Study presented at
CSUN's 17th annual international conference
"Technology and Persons with Disabilities"
March 20th 2002
Los Angeles, California, USA

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Jean-Marie D'Amour
Instructor
CAMO pour personnes handicapées
Catherine Roy
Advisor, Training and Employment Development
CAMO pour personnes handicapées

1. PERTINENCE

The World Wide Web Consortium (W3C) Web Accessibility Initiative (WAI) has published the Web Content Accessibility Guidelines 1.0 and the Techniques for Web Content Accessibility Guidelines 1.0. There are 14 guidelines and 65 check points. These check points refer to 85 different techniques. All of these elements comprise what is asked of Web developers.

However, screen reader software doesn't always provide access to information included from Web developers to ensure content accessibility. For example, complex images, like diagrams and graphics, must have a long description via the "longdesc" attribute. And only the most recent version of JAWS and IBM Home Page Reader, a voice browser, give access to this particular information. As a result, Web authors are asked to use the "longdesc" attribute and to add a d-link as an alternate solution.

Among Web accessibility experts and Web developers trying to make their sites accessible, numerous questions have been raised concerning the way various assistive software treat or simply ignore the accessibility information added to pages. Not surprisingly, developers are rather unmotivated to bring modifications that will hardly be, if at all, considered by the assistive software. And when the accessibility information is treated, they would like to understand how it will actually be rendered to users in order to adjust their methods to attain the desired results.

Unfortunately, the aforementioned example isn't an isolated case. That is why we felt it necessary to conduct this comparative study on various screen readers and text to voice browsers in order to verify to what extent these tools support Web accessibility recommended by the WAI as well as to explain how the accessibility information is treated or not and how it is transmitted to users.

Our study answers such questions and could become a useful reference tool to those concerned with Web accessibility. Additionally, our evaluation proposes recommendations for screen reader software developers that would allow them to improve support to Web accessibility. To attain this goal, there is effectively a need for Web and assistive technology developers to work together.

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2. METHODOLOGY

This comparative study assessed the most recent versions of the following software:

  • Home Page Reader from IBM (version 3.02);
  • JAWS Screen Reader from Freedom Scientific (versions 3.5, 3.71 and 4.02);
  • Windows Eyes from GW Micro.

We had intended to include Outspoken 3.0 from Alva Access Group and Hal 5.0 from Dolphin Computer Access; but, upon summary evaluation, we felt that they were too far behind their other competitors for it to be pertinent to include them in this study.

Additionally, we present results for the 2 previous versions of JAWS since this product is very widely used and many users continue to work with old versions they can't afford to update.

Among the 85 techniques recommended by the WAI, we have retained 41 elements of information included to ensure a Web page's accessibility and transmitted or not through assistive technologies. These elements are sorted into 6 categories:

  • Structure elements and user control;
  • Text equivalents;
  • Keyboard access;
  • Form information and navigation;
  • Table information and navigation;
  • Frames information and navigation.

Six of these elements are associated to accessibility but are not included explicitly in the WAI techniques or are not clearly assigned to a priority level:

  • Auto-detecting primary language;
  • Title for images and buttons;
  • Same page link;
  • OBJECT title;
  • Tabbing to non-link anchors;
  • Name of frames.

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3. RESULTS

Our comparative study reveals that HPR 3.02 and JAWS 4.02 are now about neck and neck. HPR had a comfortable lead until the release of JAWS' latest version which has undergone significant improvement. This is good news to users of this screen reader considering its dominant position on the market. The results follow:

Summary Window Eyes 4.2 JAWS 3.5 JAWS 3.71 JAWS 4.02 HPR 3.02 Total
Structure element and user control: 0 1 1 2 6 9
Text equivalents: 5 6 6 8 7 9
Keyboard access: 1,5 1 1 2,5 0,5 5
Form information and navigation: 5 5 5 6 5,5 6
Table information and navigation: 3 5 5 6 8 9
Frames information and navigation: 0 0 1 2 0 3
Total 14,5 18 19 26,5 27 41
Percentage 35% 44% 46% 65% 66%  

We obtain almost identical results if we take into account the WAI's priority levels, thus slightly widening the gap with the leader, which is IBM's Home Page Reader.

Summary weighted by priority Window Eyes 4.2 JAWS 3.5 JAWS 3.71 JAWS 4.02 HPR 3.02 Total
Structure element and user control: 0 2 2 4 11 16
Text equivalents: 13 16 16 18 17 21
Keyboard access: 2 1 1 3 1 6
Form information and navigation: 10 10 10 12 11 12
Table information and navigation: 7 11 11 14 17 20
Frames information and navigation: 0 0 1 3 0 6
Total 32 40 41 54 57 81
Percentage 40% 49% 51% 67% 70%  

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4. Discussion

We will now briefly discuss each category.

4.1. Structure elements and user control

Structure elements and user control: Priority level Window Eyes 4.2 JAWS 3.5 JAWS 3.71 JAWS 4.02 HPR 3.02 Total
Heading elements (H1-H6) 2 no no no yes yes  
Lists (ordered and unordered) 2 no no no no yes  
Nested lists 2 no no no no no  
Abbreviations and acronyms with title for expansion 3 no no no no no  
Quotations (Q and blockquote) 2 no no no no no  
Changes in language 1 no no no no yes  
Identify primary language 3 no no no no yes  
Auto-detecting primary language NCR (see Note 1) no no no no yes  
Popup 2 no yes yes yes yes  
Total 0 1 1 2 6    
Weighted by priority 0 2 2 4 11 9 16

Note 1 : Not clearly rank by WAI.

Structure elements include headings (H1-H6), lists and nested lists which are all elements of information essential to comprehending and getting one's bearings in a document. Notably, headings allow a user who can only access a sequential reading of the text to explore a document, thus compensating for the inability to get an overall view visually.

Only IBM HPR 3.02 and JAWS 4.02 indicate headers elements via an auditory signal or a configurable warning. HPR 3.02 and JAWS 4.02 also allows one to navigate by headings.

Only IBM HPR indicates the numbers of ordered lists and permits adding a warning text at the beginning of items of non-ordered lists. However, HPR does not allow the user to distinguish the indentation level of nested lists.

Primary language and changes in language are important information for voice synthesizer users. Indeed, this type of assistive technology does not make reading in another language easy without changing the language option. If not, the text is incomprehensible. Present voice synthesizers offer different languages that the user can alternate between.

IBM HPR is the only one to locate language attributes in the document and change the synthesizer engine on the fly. It can also automatically detect the document's language, even if the attribute is absent.

For all the other products, the user must him or herself modify the language when he or she detects a change in the page's content.

Identification of quotes as well as the meaning of abbreviations and acronyms are two informational elements provided for by the WAI guidelines and respectively ranked priority 2 and 3.

None of the products evaluated give this information to the user.

Popup windows are annoying for many users, which doesn't prevent site developers from using them and sometimes abusing them. They are even more disorienting for people who can't see them suddenly appear and who then find themselves in a new window without knowing. The WAI recommends users be warned that a current link will open a new window.

The 3 last versions of JAWS say "New browser window" each time a popup window appears;

IBM HPR 3.02 plays a little jingle every time it opens a new window.

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4.2. Text equivalents

Text equivalents: Priority level Window Eyes 4.2 JAWS 3.5 JAWS 3.71 JAWS 4.02 HPR 3.02 Total
Alt text for images and buttons 1 yes yes yes yes yes  
Title for images and buttons NCR yes yes yes yes yes  
Longdesc for complex images 1 no no no yes yes  
Alt text for AREAs of image maps 1 yes yes yes yes yes  
Text links 1 yes yes yes yes yes  
Same page link NCR no no no yes no  
OBJECT title NCR no no no yes yes  
OBJECT descriptive text 1 yes yes yes yes yes  
APPLET descriptive text 1 no yes yes no no  
Total   5 6 6 8 7 9
Weighted by priority   13 16 16 18 17 21

The text equivalent is a way of providing textual information about visual elements. This information is essential for blind users who cannot access the content otherwise. The HTML 4.01 Specification also provides for the possible use of the title attribute defined as "advisory information about the element for which it is set."

Window Eyes and JAWS confuse these attributes and always gives precedence to the title attribute when both are present. JAWS, before 4.02, applies this logic to textual links as well. However, a title is complementary information while an alt text is an essential way of offering a textual equivalent to visual content;

HPR reads the alt text but not the title. The ideal solution is to have access to both the alt text as the default and the title as a complement with the contextual information command;

Only JAWS 4.02 indicates if a link leads to somewhere else in the same page, which is interesting information even though it is not mentioned in the WAI guidelines;

All competitors treat NULL alt texts (ex. alt="" and alt=" ") as images without alt texts. The function of the NULL alt text is to eliminate all reference to an image because it is purely decorative and deemed unimportant. All software should add a category before the "all images" category that could be called "all images with no alt text";

Finally, let us note that HPR and JAWS 4.02 alone support the longdesc attribute, the purpose of which is to provide a link to a descriptive page for complex visual elements.

Descriptive text for OBJECTS is well supported by all products while the one for applets is only supported by JAWS 3.5 and 3.7.1. The 4.02 version of JAWS however no longer supports this feature.

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4.3. Keyboard access

Keyboard access: Priority level Window Eyes 4.2 JAWS 3.5 JAWS 3.71 JAWS 4.02 HPR 3.02 Total
Tabbing order (tabindex) for links 3 no no no no no  
Tabbing order (tabindex) in forms 3 yes yes yes yes no  
AccessKey 3 no no no yes no  
Tabbing to non-link anchors ncr no no no no no  
Scripts and DHTML 2 Partial no no partial partial  
Total   1.5 1 1 2.5 0.5 5
Weighted by priority   2 1 1 3 1 6

HTML 4.01 allows developers to define tabulation order in a document, which can be crucial with certain types of dynamic menus or javascript effects that take the keyboard into consideration, as recommended by the WAI. It is also used in forms to ensure a logical path for keyboard users.

Window Eyes and JAWS support tabulation order, but JAWS 4.02 alone indicates accesskeys;

Window Eyes alone respects Internet Explorer's tabbing to non-link anchors;

All recent versions of the assessed products partially support event handlers in javascript and DHTML effects related to layers that one modifies the visibility property. This support is however still rudimentary and is only functional in particular situations.

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4.4. Form information and navigation

Form information and navigation: Priority level Window Eyes 4.2 JAWS 3.5 JAWS 3.71 JAWS 4.02 HPR 3.02 Total
Grouping and instructions with FIELDSET and LEGEND 2 no no no yes
partial (see Note 1)  
Association between Label and Control with "for" attribute 2 yes yes yes yes yes  
Text field 2 yes yes yes yes yes  
Combo box 2 yes yes yes yes yes  
Radio button 2 yes yes yes yes yes  
Buttons 2 yes yes yes yes yes  
Total   5 5 5 6 5,5 6
Weighted by priority   10 10 10 12 11 12

Note 2 : Read Legend only when label follows control.

Forms are crucial elements for all search and e-commerce operations.

All the evaluated products support the various control elements for forms. However, JAWS 4.02 alone systematically gives information concerning element clusters and legend content which is often essential information for filling out forms correctly.

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4.5. Table information and navigation

Table information and navigation: Priority level Window Eyes 4.2 JAWS 3.5 JAWS 3.71 JAWS 4.02 HPR 3.02 Total
Abbreviations for headings 3 no no no no yes  
Caption 3 yes yes yes yes yes  
Summary 3 no yes yes yes yes  
Scope 1 no yes yes yes yes  
Headers 1 no yes yes yes yes  
Axis 1 no yes yes yes no  
Empty cells 1 yes no no yes yes  
Merged cells 1 yes no no no yes  
THEAD, TFOOT, TBODY 2 no no no no yes  
Total   3 5 5 6 8 9
Weighted by priority   7 11 11 14 17 20

A data table is a very complex environment for non-visual users. A sighted user can, with a quick glance, understand in what way the information is organized. A blind user however relies on information such as a summary to get a general idea of the table. Identifying header cells and their relation to data cells is also essential for navigation and comprehension of content.

IBM HPR is the best tool to navigate in complex data tables and Windows Eyes is the least best. JAWS 4.02 has made progress compared to its earlier versions, notably concerning empty cells but would be more interesting if it treated merged cells with the same logic as HPR.

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4.6. Frames information and navigation

Frames information and navigation: Priority level Window Eyes 4.2 JAWS 3.5 JAWS 3.71 JAWS 4.02 HPR 3.02 Total
Title of frames 1 no no no no no  
Name of frames NCR no no yes yes no  
Longdesc 2 no no no yes no  
Total   0 0 1 2 0 3
Weighted by priority   0 0 1 3 0 6

Frames are not as popular as they used to be but are still used on many sites. The WAI recommends that a title be given to each frame that is significant to its function and to provide a longdesc attribute to explain the interaction between frames if their titles are not sufficiently explicit.

JAWS 4.02 alone gives good support for frames. This support would be better if it read the title rather than the name of the frame, as recommended by the WAI.

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5. CONCLUSION

Web accessibility is an issue that must mobilize both content and assistive technology developers. If both do their part, the Web will be a much better place for everyone.

This evaluation illustrates the significant improvement of JAWS 4.02, which places it henceforth on almost equal footing with IBM Home Page Reader.

Our study has already produced a positive effect by stimulating the competitive spirit of the designers of JAWS who wanted to tie or surpass IBM Home Page Reader. If both candidates draw inspiration from their competitor's strong points and release an improved version of their product, we will have contributed in insuring a more accessible and usable Web for all users.

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