Advanced Topics in HCIT © 2014 Department of Computer Science Access to the web for disabled and...

Advanced Topics in HCIT© 2014 Department of Computer Science

Access to the web for disabled and older people

Helen Petrie


Overview

• Why worry about accessibility?

• Understanding users with disabilities relevant to Web and multimedia access

• some basic statistics and characteristics

• how they use computer technologies, the Internet

• problems they have in using the Web and multimedia applications


Why worry about accessibility?

• The legal case

– national legislation

– European directives etc

– selling to the USA: ADA and Section 508

• The business case (particularly the older market)

• The moral case

• The usability bonus


Who has difficulties with the Web?

Important to remember that it is not just people with visual impairments who have difficulty with the Web/e-services:

Visual impairments - blindpartially sighted

Hearing impairments - deafdeafenedhard of hearing

Physical impairments - dexterity problemsCognitive impairments, people with specific learning

difficultiesdyslexia


Visually impaired people – some stats and facts

• about 2 million people with severe sight problems in the UK (source: Royal National Institute for the Blind) in a population of 60 million (i.e. 1 in every 30 people)

• 82% over the age of 65, but 166,000 people of working age and 24,000 children

• only 10% see “nothing”• all want to use any vision they have• Only 5% of totally blind people read Braille


Some myths about blind people

• Very few have guide dogs (4,700 in the UK)

• They do not have super acute hearing or sense of smell (but they do make much better uses of these senses than sighted people typically do)

• They are not inherently musically • They “watch” television as much as

sighted people of similar characteristics (source: RNIB)


Visually impaired people would like ..

• Also worth noting that visually impaired people greatly appreciate audio description of multimedia material (extra verbal description of the visual aspects of the material, carefully slotted into appropriate quiet sections of the production) - currently films, theatre, opera and television

• Our survey of 111 visually impaired people for the RNIB found that this was one of the most appreciated “technological” aids


Colour vision deficiencies (“colour blindness”)

• About 10% of the population have some form of colour vision deficiency: 8 – 12% of men and 0.5% of women

• most common forms in perception of red and green (see next slide)

• Aging affects our colour perception – the average 80 year old has only 40% of the colour vision of a 20 year old

• If three Caucasian males come and look at your website, there’s a 22% chance that one of them will have a colour vision deficiency


Green weakness (Deuteranomoly)

• Affects 5 in 100 males

• Perception of green as red (missing/weak green-sensitive pigment)

• Poor discrimination in the red/orange/ yellow/green region of the spectrum


Other forms of colour vision deficiency

• There are numerous other forms of colour vision deficiency, all much rarer than deuteranomoly

• Most severe – monochromaticism, no colour vision at all

• None of these people see the world in what people with full colour vision would think of as black and white – some distinctions not made, others made in different ways

• a monochromat may actually see distinctions a full colour vision person does not see, based on differences in saturation


Blind people: technologies for computer and internet access

• People with no vision use screenreaders to access computer applications, including the Web

• Most common of these are JAWS, WindowEyes and HAL (last in the UK only) - for Windows (a new screenreader for Macs in currently under development)

• Important to remember that these do not simply “read the screen” (in spite of their name), but allow the user to interact with the information

• e.g. provide list of links, try to make use of the mark-up structure, provide a known set of commands


Blind people - technologies for computer and internet access (cont)

• Specialist Web browsers for visually impaired people have also been developed – PW WebSpeak, IBM’s HomePage Reader

• Instead of using screenreader with standard browser (e.g. Internet Explorer), can use a specialist browser

• Haven’t taken off – people are used to the commands of their screenreader, don’t want to learn another set; screenreader developers caught up with the specialist browser developers


Problems encountered by blind people when using the Web (from our DRC study)

• Incompatibilities between screenreading programs and web sites (poor coding ….)

• Incorrect or non-existent labelling of links, form elements and frames

• Unclear and confusing layout of pages• Images not labelled (with ALT text) or labels

unhelpful• Confusing and disorienting navigation

mechanisms


Partially sighted people - technologies for computer and internet access

Partially sighted people may use a screen magnification program such as ZoomText or use the accessibility settings in their browser to enlarge text, change colours of text/background etc

People with colour vision deficiencies largely use no assistive technologies, so special care needs to be taken to ensure appropriate use of colour in applications and websites


Problems encountered by partially sighted people when using the Web (from our DRC study)

• Inappropriate use of colours and poor contrast between content and background

• Incompatibilities between screen magnification programs and web sites (poor coding ….) [B]

• Unclear and confusing layout of pages [B]• Confusing and disorienting navigation

mechanisms [B]• Graphics and text size too small


Deaf and hard of hearing people – stats and facts

• There are about 9 million deaf and hard of hearing people in the UK (source: Royal National Institute of Deaf People)

• 8.8 million have an acquired hearing loss - they have become hard of hearing usually through aging

• 120,000 people are prelingually deaf - born deaf or became deaf early in life; may have difficulty with written English

• 50,000 people use a sign language as their preferred language; see themselves as a linguistic and cultural minority, rather than a disability group; English is a second language


Deaf and hard of hearing people – technologies for accessing the Internet

• Currently unlikely to use any assistive technology on the Web

• Greatly appreciate signing and subtitling of film, theatre, opera and television

• People from the Sign language community really want interpretation “from the deaf viewpoint”

• Even some signing is appreciated - in our MultiReader Project we provided signing of the navigation icons, which was greatly appreciated


Problems encountered by hearing impaired people

when using the Web (from our DRC study)

• Unclear and confusing layout of pages [B, PS]

• Confusing and disorienting navigation mechanisms [B, PS]

• Lack of alternative media for audio-based information and complex terms/language

• Inappropriate use of colours and poor contrast between content and background [PS]

• Graphics and text size too small [PS]


Dyslexia

• causes difficulties in learning to read, write and spell • Short-term memory, mathematics, concentration, personal

organisation and sequencing are not dyslexia, but may co-occur with this

• usually arises from a weakness in the processing of language-based information

• Biological in origin, it tends to run in families, but environmental factors also contribute

• can occur at any level of intellectual ability• not the result of poor motivation, emotional disturbance,

sensory impairment or lack of opportunities• effects can be largely overcome by skilled specialist

teaching and the use of compensatory strategies


Typical characteristics of dyslexia

• bright in some ways with a 'block' in others • late in learning to talk, or with speaking clearly • particular difficulty with reading or spelling• put figures or letters the wrong way e.g. 15 for 51, 6

for 9, b for d, was for saw• spell a word several different ways without

recognising the correct version• confuse left and right • answer questions orally but have difficulty writing the

answer • have trouble with sounds in words, e.g. poor sense of

rhyme


People with dyslexia – stats and facts

• About 10% of the population have some form of dyslexia

• About 4% of the population are severely affected, including 375,000 schoolchildren in the UK

• Dyslexia causes problems with reading, spelling, writing, orientation and navigation (including on web sites)

• Reading problems: words may appear to jump around the page/screen, bleed down the page, disappear, the relationship between the written form and the spoken form is very difficult to grasp


People with dyslexia – technologies

• People may use software such as SpeakOut and textHELP!

• But often don’t use assistive technology for the Web, so need to be able to adapt appearance of pages

• Short lines of text, different colour combinations and highlighting of text can help deal with some of these problems

• Text-to-speech synthesis can help people with severe dyslexia


Problems encountered by people with dyslexia when using the Web (from our DRC study)

• Unclear and confusing layout of pages [B, PS, HoH]

• Confusing and disorienting navigation mechanisms [B, PS, HoH]

• Inappropriate use of colours and poor contrast between content and background [PS, HoH]

• Graphics and text size too small [PS, HoH]• Complicated language or terminology


People with physical impairments

• People who have difficulty using a keyboard and particularly a mouse (or other pointing device) have problems using the Web

• These physical impairments can result from many conditions from RSI to spinal injuries

• People may use special keyboard and pointing devices

• People may use switch access and head mounted pointing devices (see next page)


Input and pointing devices for people with physical impairments


Problems encountered by people with physical impairments (from our DRC study)

• Confusing and disorienting navigation mechanisms [B, PS, HoH, Dys]

• Unclear and confusing layout of pages [B, PS, HoH, Dys]

• Graphics and text size too small [PS, HoH, Dys]

• Inappropriate use of colours and poor contrast between content and background [PS, HoH, Dys]


The Disability Rights Commission Formal Investigation

• I lead a team that conducted the most detailed study in the work to date on web accessibility

• we were appointed to conduct the research for a Formal Investigation of Web accessibility for the Disability Rights Commission

• Accessibility of web sites potentially comes under the Disability Discrimination Act (1995) – although the original act doesn’t mention web sites, the DRC’s Code of Practice (2002) made it clear that provision of information via the Web is a service


Overview of the FI research

• User Panel of 50 people – blind, partially sighted, deaf, hard of hearing, dyslexic

• Focus groups with User Panel members• Automated testing of 1000 home pages• In-depth automated testing and user testing

of 100 websites• Small controlled study with blind and sighted

users• Surveys of Web developers and owners


Sample of 1000 websites

• Took a representative sample of websites of interest and importance to disabled people in Great Britain

• Five main categories: Government and information Businesses (SMEs to multinationals) E-commerce (banking, travel, retail…) Entertainment and leisure Web services (ISPs, portals, search engines,

chat rooms …)


Automated testing

• Automated testing of the home pages of the 1000 sites

• Criteria: WCAG 1 - those items in the Guidelines which can be checked automatically

This covers 12 out of 65 Checkpoints

Used WebXM from Watchfire


• 19% of home pages (192) passed the automatic Priority 1 checks, so less than 19% would be fully Priority 1 compliant (WAI A Conformance)

• 51% of government Website home pages passed automatic Priority 1 checks

• Significantly better than the rest of the sample• No other differences between the sectors

Results of automated testing


Results of automated testing

• only 6 (0.6%) of all home pages passed Priority 1 + Priority 2 automatic checks

• But only 2 (0.2%) passed both automatic and manual checks at Priority 1 + Priority 2 (AA Conformance)

• No home pages passed Priority 1 + Priority 2 + Priority 3 (even automatic checks) (AAA Conformance)

• No substantial differences between government/other areas on AA and AAA results

Conclusion: basic technical accessibility very poor


• also developed two more detailed measures of website accessibility:

• Designer metric = number of different Checkpoints violated

• (relates to how many different things the designer needs to address)

• User metric = number of instances of Checkpoint violations

relates to the number of problems a user may experience on a page; of course an individual disabled user isn’t affected by all checkpoints and unlikely to read the entire page, but measures the potential number of problems

Measuring accessibility in more detail


Example of the two new metrics

Different Checkpoints violated on a particular page:

1.1 provide alt text on images

12.1 title each frame

Designer metric = 2

Instances of Checkpoint violations on a particular page:

no alt text on images 10

frames not titled 3

User metric = 13


Results on the metrics

Designer metrica mean of 7.7 different Checkpoints violated/home page

plus a mean of 39 different Checkpoints warnings

[Government websites: 6.0 (+ 35 warnings)]

User metric a mean of 108 instances of violations per home page

plus a mean of 239 instances of warnings

Government websites: 60 instances of violations (+ 195 warnings)

Conclusion: no wonder disabled people have problems with the Web


In-depth automated and user testing of 100 Websites

Selected 100 websites from the 1000 on the basis of a number of measures:

the 5 categories

use of different Web technologies

accessibility level on automated testing


More automated testing

• Automated testing of whole site or the first 500 pages in the site

• In total we conducted automated testing on 39,000 web pages


User evaluations

• Fairly standard user testing – concurrent verbal protocols

• Because of the amount of data that we wanted to collect in the time available, couldn’t do all the testing with a researcher in the lab

• One session in the lab evaluating 2 – 3 web sites, and teaching participants how to conduct an evaluation on their own

• Each participant evaluated 7 – 8 web sites alone, making a total of 10 evaluations per participant


User evaluations

• target was 1000 tasks = 50 users x 10 sites x 2 tasks

• Each Web site evaluated by at least 5 users, one each from the different user groups

• 913 tasks actually attempted, logged and analysed

• We compared data collected in the lab to data collected alone, and found no differences in effects, although the quantity of data collected when working alone was smaller


Results: Success at tasks

• Overall, panel members were successful on (only) 76% of the tasks

• but also significant differences between impairment groups:

blind successful on 53%partially sighted: 76%dyslexic: 83%Deaf/hearing impaired/physically impaired: 85%


Ease of task ratings

Difficult …. Easy

Blind 61% 32%PS 48 51Dyslexic 43 53Deaf/HH 36 63PI 29 64

So, partially sighted and dyslexic people also disadvantaged, although not as severely as blind people


Accessibility problems the users encountered

585 instances of problems were encountered

55% (319) would probably have been avoided if WCAG had been followed, but 45% not (266)

Guidelines are NECESSARY but not SUFFICIENT – amazing result to the Web community, shouldn’t really surprise the HCI community


Relationship between WCAG conformance and user testing

• We investigated the relationship between the WCAG conformance (total number of checkpoint violations/warnings, number of Priority 1,2 and 3 violations/warnings, Designer measure, User measure) and the user testing results (success/fail, ratings of ease of use …)

• No significant correlations at all• This does need further work - currently data

mining this data set


What is the relationship between accessibility and usability?

“pure” accessibility – one or more disabled groups can’t access information, able-bodied people can

no ALT text, graphical textblind people can’t access that information, able-bodied people fine

Both accessibility and usability – both disabled and able-bodied people affected, disabled people more than able-bodied

Navigation schema on the Olympics Games Web site


Olympic Games 2004 Web site


Two conceptual problems

Relationship between accessibility and usability

Relationship between conformance to WCAG and ability of disabled people to use websites


Definition of web accessibility


The usability bonus

• We conducted a small, conducted study of web sites

• High accessibility – performed well on WCAG and disabled user testing

• Low accessibility – performed poorly on WCAG and disabled user testing

• Asked a group of blind people (using screenreaders) and a matched group of sighted people to perform a series of standard tasks on the web sites


task completion times


Results in words

• Sighted people were 35% faster on the high accessibility web sites than on the low accessibility web sites

• Analysis of the problems the disabled users encounter will also reveal many/all of the usability problems of the site

• So, investigating accessibility will yield a usability bonus as well


Conclusions

• The characteristics and needs of people with disabilities are often different from the stereotypes we have

• The more we understand about people’s real needs and the ways they currently use technologies, the easier it is to provide accessible web sites and e-services

• No-one is expecting developers to spend huge amounts of time on this, but a little investment of time will be well repaid

• Understanding accessibility at either a conceptual level or a practical level is a lot more complex than you might imagine


Resources

Terminology about people with disabilities: http://hub.eaccessplus.eu/wiki/Terminology_for_writing_about_people_with_disabilities

Disability Rights Commission (2004). The Web: Access and inclusion for disabled people. London: The Stationery Office.

Petrie, H. and Bevan, N. (2009). The evaluation of accessibility, usability and user experience. In C. Stephanidis (Ed). The Universal Access Handbook. London: Taylor and Francis.

Petrie, H. L. and Kheir, O. (2007). The relationship between accessibility and usability of websites. ACM CHI 2007 Conference on Human Factors in Computing Systems. New York: ACM Press.


More resources

Power, C., Freire, A., Petrie, H. and Swallow, D. (2012). Guidelines are only half the story: accessibility problems encountered by blind users on the web. Proceedings of the 30th International Conference on Human Factors in

Computing (CHI 2012). New York: ACM Press.

Freire, A.P., Petrie, H., and Power, C. (2011). Empirical results from an evaluation of the Accessibility of websites by dyslexic users. In Proceedings of the Workshop on Accessible Design in the Digital World 2011, Lisbon, Portugal, September 5, 2011.

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