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A Cognitive Basis for Web Design:Accommodating Perceptual and Structural StylesRecommendations made to the WAI Content Guidelines Working Group Authored by Greg Gay (ATRC-6-2000) Contents
I recently returned to the w3c-wai-gl list after a long while, to find some great discussion surrounding cognitive accommodations as a part of accessible web design. I don't see much agreement though. Perhaps a model of cognition that roughly parallels the WAI distinction between structure and presentation, will help frame the content guidelines for accommodating or compensating for cognitive disabilities*. One of the problems in developing these guidelines has been trouble interpreting instructional design principles for accommodating those with cognitive disabilities, in terms of more practical Web design strategies. The model that follows may help add order to the task. A Cognitive Basis for Web DesignThere is a general agreement that it would be unrealistic to require Web designers to include accommodations for every aspect of cognitive disabilities. Where do you draw the line on accommodation? A more general approach to accessible web design may be helpful, based on what we know about designing accessible documents for those with sensory disabilities (e.g. separate structure from presentation, alternative formats ), and what we know about learning, and the construction and retrieval of knowledge (perceptual and structural cognition). Thinking in terms of discrete disabilities creates too many ill-defined categories of disability, making it difficult to accommodate them all, and to define where accessibility issues overlap. Given the diversity of cognitive disabilities, it is easier to think in terms of individuals possessing a collection of processing skills, each of which is represented on a continuum of ability. Imagine a bar chart in which each ability is represented in a bar, and the height of each bar represents the amount of ability in that domain. When one of these abilities is deficient (i.e.. disabled), or falls at the lower end on of its continuum, it is often the case that other abilities develop to compensate for the weakness. For example, there is evidence that suggests that some people with print impairments (phonological processing deficits) develop heightened visual processing skills. The analogy being, a person who is blind will develop heightened auditory and tactile skills. The following model has emerged out of work I've been involved in over the past ten years, studying cognitive disabilities, adaptive instruction, and more recently web accessibility. It is a cognitive model interpreted within the context of the WCAG 1.0. Where each of the items in the model fall on a scale of priorities, remains an issue. 1. Perceptual CognitionEach of the four areas of perceptual processing is represented roughly by the distinction between external stimuli and internalized knowledge: a) you would learn by seeing external stimuli, and recall by imagining internalized knowledge; b) learn by hearing, and recall by reciting; c) learn by doing, and recall by reliving the experience; d) learn by reflection, and recall by cueing. a. visual/imagery
b. auditory/verbal(textual)
c. kinaesthetic/experiential
d. awareness/prior knowledge
2. Structural CognitionThe structural aspects in designing Web documents to accommodate cognitive disabilities are accomplished by providing variety in the navigation tools a site uses. All Web users tend toward using particular navigation strategies: generally, those that match their skills or preferences. They may prefer a global representation of the site such as a site-map, table of contents, or index. They may prefer a more general, less comprehensive, central navigation point such as a home page. They may prefer ordered information, navigating with page back/forward links or buttons. Others may prefer little or no structure. These latter users can benefit from a search engine, getting them to the information they need through the shortest possible route, bypassing that information they don't see as relevant. a. global/webbed
b. sequential/linear
c. hierarchical/tiered/modular
WAI WCAG 1.0 guidelines for accommodating cognitive disabilitiesThe current guidelines address many issues of accommodation for cognitive disabilities, though recommendations lean toward accommodating those who use adaptive technology rather than those who use, or could benefit from, adaptive behaviour. Adaptive technology used by those with cognitive disabilities to access Web content consists primarily of screen readers, for serious print impairments, and text-to-speech, for less serious print or receptive language impairments. Symbol systems such as Bliss may be used for more general cognitive impairments. As is often the case, accommodations made for one group also benefit the others (i.e. curb cuts). Symbols, in the general sense (i.e. . re- representations of meaning), play a major role in the cognitive activity of everyone. The study of signs and symbols (semiotics) identifies symbol systems as the root of all learning and behaviour. All we come to know is stored in knowledge in symbolic form, the most notable of which are spoken and written language, represented in phonemes and graphemes (sounds and letters). Some symbol systems can transcend language, such as the symbol to stop, or for a rest room, a telephone, or an off ramp, to name just a few. Each carry meaning in graphical form, though each has meaning in other symbol systems. For example, in addition to the standard red octagon, the notion of "Stop" can be symbolized using text, as in the letters just presented between the quotes. It can be symbolized in auditory form, saying the word or its letters. It can be gestured, holding an arm out horizontally with the palm facing out. I'm sure there are other ways to convey the same meaning: the point being, the more representations there are the more likely the meaning being conveyed will be understood. Adaptive behaviour is accommodated by providing variety. From a perceptual standpoint, providing alternative formats for visual, auditory, and textual content promotes adaptive behaviour; in all likelihood the vast majority of those with a disability will be able to process at least one of those formats. Alternative formats can help compensate for tendencies or abilities to construct and process knowledge through particular perceptual modes. From a structural standpoint, simple and clear content and navigation increases accessibility for those with sensory disabilities as well as those with cognitive disabilities (not to mention everyone else), by reducing the "load" on cognitive processing. WAI Guidelines that support accommodation of cognitive disabilitiesThe following is a list of WCAG 1.0 check points that either directly or indirectly address Web accessibility issues for those with cognitive disabilities, based on the model outlined above. For more detail view the WCAG 1.0 (http://www.w3.org/TR/WAI-WEBCONTENT/) ( P1 = Priority 1; P2 = Priority 2; P3 = Priority 3) 1.1 Provide a text equivalent for every non-text element. (P1) 1.2 Provide redundant text links for each active region of a server-side image map (P1) 1.3 ...provide an auditory description of the important information of the visual track of a multimedia presentation. (P2) 1.4 ...synchronize equivalent alternatives with the presentation. (P1) 1.5 ...provide redundant text links for each active region of a client-side image map.(P3) 2.1 Ensure that all information conveyed with color is also available without color (P1) 2.2 ...[for] color combinations provide sufficient contrast (P2 & P3) 3.1 ...use markup rather than images to convey text and control layout.. (P2) 3.3 Use style sheets to control layout and presentation (P2) 3.5 Use header elements to convey document structure.... (P2) 3.6 Mark up lists and list items properly (P2) 4.2 ...expansion of each abbreviation or acronym in a document where it first occurs. (P3) 5.1 For data tables, identify row and column headers. (P1) 5.2 ... use markup to associate data cells and header cells. (P1) 5.3 Do not use tables for layout unless the table makes sense when linearized (P2) 5.5 Provide summaries for tables. (P3) 6.1 Organize documents so they may be read without style sheets (P1) 6.2 Ensure that equivalents for dynamic content are updated (P1) 6.3 Ensure that pages are usable when programmatic objects are turned off (P1) 6.4 ...ensure that event handlers are input device-independent. (P2) 6.5 Ensure that dynamic content is accessible or provide an alternative presentation or page. (P2) 7.0 Ensure user control of time-sensitive content change (P1 - P2) 9.0 Design for device independence. (P1 - P3) 10.3 ...provide a linear text alternative for all tables that lay out ...word-wrapped columns. (P3) 10.5 include non-link, printable characters between adjacent links. (P3) 11.3 Provide information so that users may receive documents according to their preferences (P3) 12.2 Describe the purpose of frames and how frames relate to each other ....(P2) 12.3 .. [block] information into more manageable groups where natural and appropriate.(P2) 13.1 Clearly identify the target of each link. (P2) 13.2 Provide metadata to add semantic information to pages and sites. (P2) 13.3 Provide information about the general layout of a site (P2) 13.4 Use navigation mechanisms in a consistent manner. (P2) 13.5 Provide navigation bars to highlight and give access to the navigation mechanism.(P3) 13.6 Group related links (P3) 13.7 ...enable different types of searches for different skill levels and preferences. (P3) 13.8 Place distinguishing information at the beginning of headings, paragraphs, lists, etc. (P3) 13.9 Provide information about document collections (P3) 14.1 Use the clearest and simplest language appropriate for a site's content. (P1) 14.2 Supplement text with graphic or auditory presentations where they will facilitate comprehension... (P3) 14.3 Create a style of presentation that is consistent across pages. (P3) (NOTE: confusion or conflict in Priority: ------- 5.3 Do not use tables for layout unless the table makes sense when linearized. Otherwise, if the table does not make sense, provide an alternative equivalent (which may be a linearized version). [Priority 2] ------- 10.3 Until user agents (including assistive technologies) render side-by-side text correctly, provide a linear text alternative (on the current page or some other) for all tables that lay out text in parallel, word-wrapped columns. [Priority 3] ------- ) What should be changed?A number of existing guidelines could be modified to reflect a growing awareness of accessibility issues for those with cognitive disabilities. 1.1 Provide a text equivalent for every non-text element The graphical representation of text should be discouraged. Few, if any, of the current text-to-speech (TTS) programs will read ALT text. Thus text displayed in images, even when these images include ALT text, will be inaccessible to a user with a print impairment who relies on TTS output of Web pages. (14.2 below seems to have this covered) 1.2 & 1.5 Provide redundant text links for server-side ... and client-side image maps For the same reason text should not be displayed as an image if an alternative is not provided, redundant text links should be included for link areas of both client-side and server-side image maps. Not providing alternative text links with client side image maps may make them inaccessible to TTS users if the image maps themselves contain text. 2.0 Don't rely on colour alone. Colour is an excellent way to structure information, associating meaning with a visual cue. Guideline 2 effectively discourages the use of colour through the language used to define it, though rightfully asserts that colour should not be the sole basis for conveying information. However, use of colour should be encouraged in addition to other methods of conveying meaning, rather than to the exclusion of other methods. 11.0 Use W3C technologies and guidelines Reword "When inaccessible technologies (proprietary or not) [are] used, equivalent [W3C compliant] pages must also be provided". Non-W3C formats should not be excluded. Encourage alternative formats in addition to W3C formats. Some would rather read from a PDF document than an inferior copy displayed as a web page. The navigation features of PDF files also make them attractive to some with a cognitive disability. Designers should be encouraged to keep accessibility in mind when they create these documents, so that the available accessibility features of authoring tools are more likely to be used. PDF files created correctly are accessible to TTS programs, and given the usual superior visual quality of PDF documents over HTML, PDF files are often preferable. 14.1 Use the clearest and simplest language appropriate for a site's content. Who is the site's audience? If a site's audience is meant to be a specific group, language appropriate to that group should be used: the clearest language, but perhaps not the simplest. Some times jargon is necessary to convey the clearest meaning. Some clarification is needed on this guideline. The P1 priority level of this item should be lowered to P2. 14.2 Supplement text with graphic or auditory presentations where they will facilitate comprehension ... Alternative formats for text should be provided to facilitated comprehension and convey meaning equivalence wherever possible. In addition to accommodating those with print impairments, supplemental media formats improve comprehension for those who do not need an alternative to print. The P3 priority level of this item should be raised to P2. 14.3 Create a style of presentation that is consistent across pages. A consistent presentation is a crucial part of making a site usable for some users with a cognitive disability, but also provides benefits to those with other disabilities, as well as those without disabilities. Consistent use of inconsistencies can also be a powerful teaching tool or cueing device. The P3 priority level of this item should be raised to P2. Where additions could be made to promote accommodations for cognitive disabilities1. Providing alternative formats warrants it's own theme. It is already an important part of the guidelines for accommodating sensory disabilities, and it is a crucial part of accommodating cognitive disabilities. 2. Standard print documents rarely span beyond 18 centimetres ( 7 inches) in width. Without control over the width of a web document, print can span across an entire screen, 30 centimetres or more. This is unnaturally wide and more strenuous to read than print read from a standard 8 ½ by 11 inch page. Excessively wide text can be particularly strenuous for a reader with a print impairment. The CSS width attribute is the preferred solution to narrow pages, though less desirable tables can also be used to produce the same effect 3. More emphasis should be placed on the use of CSS. There is already a strong push toward adopting CSS. It is perhaps the most useful accessibility tool currently available, as well as being one of the most useful time saving devices for Web designers. Guideline 3.3 is currently a P2, and should be reconsidered as a P1 item. 4. Move accessibility from the realm of disability to the realm of cognition: ask what media formats are people able to process, rather than asking what media formats are they not able to process. This may be a tall order, but it makes sense in a society that is beginning to look at disabilities as differences, rather than an inability. *Less than normal intellectual capacity as been grouped with the various cognitive deficits associated with learning disabilities, into a single category named "Cognitive Disability". Good references from recent discussion on accessibility and CD A Fresh Look at Accommodating Cognitive Disabilities Cognitive Access Three Types of guidelines or strategies? Kynn's Analysis of CD Web Accessibility Re: Cognitive issues (was Re: woodcutter) Some concrete suggestions Re: Cognitive issues (was Re: woodcutter) Re: Cognitive issues (was Re: woodcutter) Re: Breaking it Down: Types of Cognitive Disabilities Re: Breaking it Down: Types of Cognitive Disabilities Cognitive Framework and Topics Re: Some concrete suggestions Re: Cognitive issues (was Re: woodcutter) |
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