Easy Does It: More Usable CAPTCHAs
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 a new CAPTCHA schemes for Google that focus on maximizing usability. Our new scheme which is now an integral part of our production system and is served to millions of users, achieved a 95.3% human accuracy, a 6.7% improvement compared to the old one.
@CHI, April 2014