evaluating accessibility-in-use
DESCRIPTION
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.TRANSCRIPT
Evaluating Accessibility-in-Use
Markel Vigo1 & Simon Harper2 University of Manchester (UK)
1: @markelvigo2: @sharpic
W4A 2013
[email protected]@manchester.ac.uk
http://dx.doi.org/10.6084/m9.figshare.701482
Evidence
Guidelines cover around 53% of the problems encountered by users
Power et al. 2012
Guidelines are only half of the story: accessibility problems encountered by blind users on the web CHI 2012, 433-442
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Problem
The perception of users about accessibility barriers is difficultly measurable and
generalisable
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Paradox
– Some barriers are not perceived– Some barriers are encountered but overcome– Barrier free pages can cause a great hindrance
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Accessibility-in-use
“the effects that real accessibility problems have on the quality of interaction as perceived by real
users when interacting with real pages for achieving real goals”
Vigo and Brajnik, 2011
Automatic web accessibility metrics: where we are and where we can go Interacting with Computers 23 (2), 137-155
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What do we propose: Step 1. Observation & Identification
of Coping Strategies
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1. Observation
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Cognitive markers that indicate problematic situations
What do we propose: Step 2. Development of algorithms to detect strategies
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1. Observation 2. Algorithms
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What do we propose: Step 3. Deployment in the wild
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1. Observation 2. Algorithms 3. Deployment
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Case studyStep 1. Observation and analysis
• 2 independent studies/datasets generated from ethnographic studies and user tests
• 24 screen reader and screen magnifier users
• 17 coping strategies were identified
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Case studyStep 2. Implement algorithms
– Asking for assistance– Impulsive clicking– Exploration tactics– Narrowing down search– Gaining orientation– Re-doing– Not operating– Giving up
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WebTacticst1(){..}
DB
User Website Manager /Researcher
1.1 Detection algorithms are injected onto web pages.
1.2 Each algorithm keeps track of determined sequences of events and actions.
3. This event is asynchronously sent to a remote location.
2. When the use of a tactic is detected a notification is triggered.
4. Reports from users are viewed by interested parties.
ti(){..}
tn(){..}
id timestamp URL tactic
ccgu1331569030153 1333922552190 http://www.bbc.co.uk/sport/ t5
ccgu1331569030153 1333922556391 http://www.bbc.co.uk/sport/ t1
W4A 201313 May 2013
Case studyStep 3. Deployment: WebTactics
Contributions
• A method to observe accessibility-in-use
• Our approach allows to capture the problems that emerge in the wild
• WebTactics
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Follow up
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Contact@markelvigo | [email protected]
Presentation DOIhttp://dx.doi.org/10.6084/m9.figshare.701482
Source codehttps://bitbucket.org/mvigo/cope
W4A 201313 May 2013