Jeffrey P. Bigham

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WebinSitu
A Comparison of Blind and Sighted Browsing
Behavior
Jeffrey P. Bigham Anna C. Cavender, Jeremy T.
Brudvik, Jacob O. Wobbrock and Richard E.
Ladner Computer Science Engineering The
Information School University of Washington
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Study Overview
Introduction

• Proxy-based observation for one week
• 10 Blind and 10 Sighted (Ages 18-63)
• Either Internet Explorer or Firefox
• Blind participants used JAWS
• 21,442 Pages
• 4,204,904 Events

Geographic Diversity of Users
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in situ Study
Introduction

• Valuable Qualities
• Participants use their own tools
• Familiar, preferred web pages
• Observe longer time periods
• Usage Patterns in Usual Browsing
• Effects of web accessibility
• Coping strategies employed
• Differences in content chosen to view

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Important Complement to Prior Work
Introduction
1 Takagi et al. Analysis of navigability of
Web applications for improving blind usability.
2007. 2 Watanabe et al. Experimental
evaluation of usability and accessibility of
heading elements. 2007. 4 Coyne et al. Beyond
alt text Making the web easy to use for users
with disabilities. 2001. 3 Lazar et al.
Determining the impact of computer frustration on
the mood of blind users. 2006.
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Outline

• Introduction
• Experimental Setup and Study Design
• Browsing Differences
• Effects of Content

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A Proxy-Based System
Setup and Study Design

• Used UsaProxy1

1 Richard Atterer et al. Knowing the User's
Every Move - User Activity Tracking for
Website Usability Evaluation and Implicit
Interaction. WWW 2007
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More than a regular proxy
Setup and Study Design
Requests
GET http//webinsight.cs.washington.edu/, 10 Oct
2007 041230 GET http//webinsight.cs.washington.
edu/pics/web-eye.gif, 10 Oct 2007 041230 GET
http//webinsight.cs.washington.edu/css/style.css,
10 Oct 2007 041231
Actions
Keypress, ctrl f, 10 Oct 2007 041235 Mouse,
540x232, 10 Oct 2007 041236 Focus, Text Box
(name), 10 Oct 2007 041236 AJAX,
urlhttp//www.cs.washington.edu/.../foo.php, 10
Oct 2007 041236 Page Changed, 10 Oct 2007
041239
Content
Image, altContact Us, srchttp//www.washingto
n.edu/pics/contact.gif Link, nameUniversity of
Washington, urlhttp//www.washington.edu
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Easy Setup and Deployment
Setup and Study Design

• No New Software to Install
• Works with Existing Tools

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Outline

• Background
• Experimental Setup and Study Design
• Browsing Behavior
• Effects of Content

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Using the Mouse
Browsing Differences

• Blind Users Dont Use a Mouse
• but, sometimes they have to

of Pages with Mouse Movements per Participant
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Using the Mouse (why)
Browsing Differences

• if there's a command in a form or shopping
  cart that says, click here, with no labeled
  button, I must route my cursor to that position

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Probing
Browsing Differences
Following a link and returning in less than 30
seconds
Call for Papers
technical papers
Technical Program
technical program
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Web Pages with Probes
Browsing Differences
(p lt 0.01)
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Browsing Efficiency
Browsing Differences

• Blind Users Less Efficient
• Overall, 2x longer per page
• Contrast to 10x on completing tasks1
• Why not more?
• Web pages, not tasks
• Accustomed to Web Pages
• errors (including probing)

(p lt 0.1)
1 Takagi et al. Analysis of navigability of
Web applications for improving blind usability.
2007.
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Using Google
Browsing Differences
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Outline

• Background
• Experimental Setup and Study Design
• Browsing Differences
• Effects of Content

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Images and Alternative Text
Effects of Content
(empty)
Blind Users are Smart
http//www.domain.com/proceed.gif http//www.domai
n.com/pubbank-button.gif http//www.domain.com/239
080s.gif
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Images and Appropriate Alt. Text
Effects of Content

• of Images with App. Alt. Text
• Did not influence browsing behavior
• Influenced Clicking Behavior

Clicked Images with App. Alt. Text
(p lt 0.01)
of Images Assigned Appropriate Alternative Text
on Visited Pages
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Skip Links
Effects of Content
Skip top navigation and go to home page content
822 Skip Links Blind users clicked 5.6 Skip
links are almost always broken.
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Effects of Content

• Dynamic Content
• 15.0x fewer pages viewed (p lt 0.07)
• 19.3x fewer interactions with dynamic content (p
  lt 0.01)
• AJAX
• 7.5x fewer (p lt 0.05)
• Flash
• 44.1 were ads
• Blind participants used for sound content
• Only 5.6 were main content

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Summary and Future Work
Effects of Content

• Main Points
• Facilitated new type of study
• Confirmed anecdotal observations
• Interesting new directions
• Many Remaining Questions
• Efficiency and experience
• Content requires using the mouse
• Annotation of dynamic content (ARIA)
• Extent of Flash accessibility
• MANY OTHERS

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The End
WebInSight webinsight.cs.washington.edu
Thanks to National Science Foundation Max
Aller, Richard Atterer, Darren Gergle, Steve
Gribble, Sangyun Hahn, Scott Rose, Lindsay
Yazzolino.
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Important Complement to Prior Work
Background and Motivation
1 Takagi et al. Analysis of navigability of
Web applications for improving blind usability.
2007. 2 Watanabe et al. Experimental
evaluation of usability and accessibility of
heading elements. 2007. 3 Lazar et al.
Determining the impact of computer frustration on
the mood of blind users. 2006. 4 Coyne et al.
Beyond alt text Making the web easy to use for
users with disabilities. 2001.