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Evaluating Accessibility-in-Use


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Evidence suggests that guidelines employed in conformance testing do not catch all the accessibility barriers encountered by users on the Web. Since accessibility is strongly tied to the users’ experience there is a subjective perception of accessibility barriers and their severity. What is more, not only intangible qualities characterise the way in which these barriers are perceived, but also navigation styles, age, onset, expertise and abilities play a key role. In order to overcome the limitations of conformance testing and catch the problems that emerge during the interaction we propose a user-interaction-driven method to automatically report accessibility problems. To do so, we initially isolate the problematic situations faced by users and the tactics employed in such situations. These tactics are considered behavioural markers of cognitive processes that indicate problematic situations; the presence of tactics denotes the presence of problems. Then, we design and deploy algorithms to automatically detect the exhibition of these tactics and consequently detect problematic situations. WebTactics, a tool that unobtrusively detects and reports the problematic situations undergone by visually disabled users illustrates the method we propose.

Published in: Design, Technology
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Evaluating Accessibility-in-Use

  1. 1. Evaluating Accessibility-in-UseMarkel Vigo1 & Simon Harper2 University of Manchester (UK)1: @markelvigo2: @sharpicW4A
  2. 2. EvidenceGuidelines cover around 53% of the problemsencountered by usersPower et al. 2012Guidelines are only half of the story: accessibility problems encountered by blind users on the webCHI 2012, 433-442W4A 201313 May 2013 2
  3. 3. ProblemThe perception of users about accessibilitybarriers is difficultly measurable andgeneralisableW4A 201313 May 2013 3
  4. 4. Paradox– Some barriers are not perceived– Some barriers are encountered but overcome– Barrier free pages can cause a great hindranceW4A 201313 May 2013 4
  5. 5. Accessibility-in-use“the effects that real accessibility problems haveon the quality of interaction as perceived by realusers when interacting with real pages forachieving real goals”Vigo and Brajnik, 2011Automatic web accessibility metrics: where we are and where we can goInteracting with Computers 23 (2), 137-155W4A 201313 May 2013 5
  6. 6. What do we propose:Step 1. Observation & Identificationof Coping Strategies61. ObservationW4A 201313 May 2013Cognitive markers that indicateproblematic situations
  7. 7. What do we propose:Step 2. Development of algorithmsto detect strategies71. Observation 2. AlgorithmsW4A 201313 May 2013
  8. 8. What do we propose:Step 3. Deployment in the wild81. Observation 2. Algorithms 3. DeploymentW4A 201313 May 2013
  9. 9. Case studyStep 1. Observation and analysis• 2 independent studies/datasets generatedfrom ethnographic studies and user tests• 24 screen reader and screen magnifierusers• 17 coping strategies were identified9 W4A 201313 May 2013
  10. 10. Case studyStep 2. Implement algorithms– Asking for assistance– Impulsive clicking– Exploration tactics– Narrowing down search– Gaining orientation– Re-doing– Not operating– Giving up10 W4A 201313 May 2013
  11. 11. 11WebTacticst1(){..}DBUser Website Manager/Researcher1.1 Detectionalgorithms areinjected onto webpages.1.2 Each algorithm keeps track of determinedsequences of events and actions.3. This event isasynchronously sentto a remote location.2. When the use of atactic is detected anotification is triggered.4. Reports from users areviewed by interested parties.ti(){..}tn(){..}id timestamp URL tacticccgu1331569030153 1333922552190 t5ccgu1331569030153 1333922556391 t1W4A 201313 May 2013Case studyStep 3. Deployment: WebTactics
  12. 12. Contributions• A method to observe accessibility-in-use• Our approach allows to capture theproblems that emerge in the wild• WebTacticsW4A 201313 May 2013 12
  13. 13. Follow up13Contact@markelvigo | DOI code 201313 May 2013