sadie - exposing implicit information to improve accessibility
Post on 06-Jul-2015
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SADIeExposing Implicit Information to
Improve Accessibility
Darren LunnSchool of Computer Science
The Web…• Designed with a focus on presenting information in a
visual manner● Images● Columned Layout● Chunks
• Some knowledge is only available implicitly from how the page looks
Implicit Knowledge
= Advertisement
= Banner
= Main Content
= Menu
Assistive Technologies
• Traversal of content is in a serial “top-to-bottom”, “left-to-right” manner.
• Important information may not be encountered until later on.
• Also, information such as menus or navigation may be repeated for every page on a site● This can prove tiresome if the user has to wait for the reader
to read the menu each time a new page is visited.
Transcoding
• Rules / Patterns● Can Adapt a large number of pages● Can Suffer from Reduced Accuracy Issues
• Annotation● Accurate● Time Consuming As Every Page Is Annotated
SADIe Approach
• The visual rendering of a Web element informs the user of its purpose
• The CSS defines the visual rendering
• Identifying the purpose of a CSS definition implicitly identifies the purpose of the Web element
• A single CSS definition is applied to every page within the Website
SADIe Functionality
• Defluff: Removes any element that is considered unnecessary
• Reorder: Rearranges the page by putting important information near the top
• Menu: Exposes the menu at the very top for immediate access
Original CNN
SADIefied CNN
Evaluation
• We want to show that using SADIe decreases the time it takes to find information on the page
• Only a small number of users available for evaluation
• Use Randomization Testing● Data analysis techniques suitable for small numbers of users
A-B-A Reversal Method
• Two Conditions; A and B● Condition A: Unmodified Pages● Condition B: Pages Adapted With SADIe
• Present the participant with Condition A tasks
• At a random point, switch to Condition B tasks
• At a second random point, revert back to Condition A tasks
• This reduces the influence of external factors on the results● Participant has time to relax● Participant becomes familiar with the task at hand
Evaluation Method
• 20 pages that had similar content that was predominantly text based● News e.g. CNN, BBC, New York Times…● Blogs e.g. Blogger, Xanga…
• Asked the user to find facts that were as similar for each page possible● Eg for news sites “What is the headline of the news story?”
• The user was presented with a page one at a time, some of which were SADIefied (Condition B)
• We timed how long it took the user to answer the question
Evaluation Results
75
21.143
50.429
0
10
20
30
40
50
60
70
80
A B A
Condition Shown To User
Sverage Time To Complete Task (s)
Evaluation Results
• So far we have evaluated SADIe with a single user
• Results are encouraging and are significant using Randomization Testing…
• … but are currently recruiting more users to support our results.
Further Work
• This is still preliminary work, and much remains to do
• Extend and Enhance the Transformations
• (Semi)-Automation of CSS classification
• More User Evaluations
Conclusions
• Browsing the Web can be difficult for those who are visually impaired
• SADIe can adapt Web pages by using rendering information extracted from the CSS
• Initial evaluation results are promising and show that SADIe can help visually impaired users reach content more quickly
• More work still needs to be done
Questions?
http://hcw.cs.manchester.ac.uk/research/sadie
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