Easy Does It: More Usable CAPTCHAs
Venue
CHI '14 Proceedings of the SIGCHI Conference on Human Factors in Computing Systems, ACM, 1600 Amphitheatre Pkwy (2014), pp. 2637-2646
Publication Year
2014
Authors
Elie Bursztein, Angelika Moscicki, Celine Fabry, Steven Bethard, John C. Mitchell, Dan Jurafasky
BibTeX
Abstract
Websites present users with puzzles called CAPTCHAs to curb abuse caused by
computer algorithms masquerading as people. While CAPTCHAs are generally effective
at stopping abuse, they might impair website usability if they are not properly
designed. In this paper we describe how we designed two new CAPTCHA schemes for
Google that focus on maximizing usability. We began by running an evaluation on
Amazon Mechanical Turk with over 27,000 respondents to test the us- ability of
different feature combinations. Then we studied user preferences using Google’s
consumer survey infrastructure. Finally, drawing on the insights gleaned during
those studies, we tested our new captcha schemes first on Mechanical Turk and then
on a fraction of production traffic. The resulting scheme is now an integral part
of our production system and is served to millions of users. Our scheme achieved a
95.3% human accuracy, a 6.7% improvement.
