LAUSR

This paper presents an analysis of the CAPTCHA interfaces in terms of their usability to Internet users. The usability is represented by the time needed to the users for finding a solution to the CAPTCHA, which is called response time. Specifically, the analysis is focused on four examples of text and image-based CAPTCHA. The aim is to study the cognitive factors influencing the Internet users in finding a solution to these four CAPTCHA types. Accordingly, an experiment is conducted on 100 Internet users, characterized by demographic factors, such as age, gender, Internet experience, and education level. Each user is asked to solve the four CAPTCHA types, and the response time for each of them is registered. Collected data including demographic factors and response time is subjected to association rule mining, using the FP-Growth algorithm for extracting the association rules. They show the dependence of the response time on the co-occurrence of the demographic factors. Also, an additional statistical analysis is performed using the nonparametric one-way Kruskal Wallis’ test. Experiments comparing the proposed method with the earlier studies of the CAPTCHA usability show the novelty of the method for the understanding of usability of CAPTCHA interfaces, which is based on the cognitive factors that influence the response time.