Multi-Factor CAPTCHA: A Usability Study

CAPTCHAs are an important tool for distinguishing human users from computer programs.This paper presents a user study that examined the accuracy, error rate, and user preference for different CAPTCHA schemes, both in a traditional single-factor mode and in a multi-factor mode that combines two different CAPTCHA types in a single challenge.The study involved participants interacting with various CAPTCHA challenges, while collecting data on errors, completion time, and user ratings.Analysis of the collected data revealed that text-based CAPTCHAs had higher error rates than the other types in both single-factor and multi-factor modes.The checkbox CAPTCHA was found to have the highest accuracy and likability in both authentication modes.Conversely, the audiobased CAPTCHA was the least preferred method by users and also the slowest to complete.