Response time analysis of text-based CAPTCHA by association rules

The paper introduces and discusses the usability problem of text-based type of CAPTCHA. In particular, two types of text-based CAPTCHA, with text and with numbers, are in the focus. The usability is considered in terms of response time to find a solution for the two aforementioned types of CAPTCHA. To analyze the response time, an experiment is conducted on 230 Internet users, characterized by multiple features, like age, number of years of Internet use, education level, response time in solving text-based CAPTCHA and response time in solving text-number-based CAPTCHA. Then, association rules are extracted from the values of these features, by employing the Apriori algorithm. It determines a new and promising statistical analysis in this context, revealing the dependence of response time to CAPTCHA to the co-occurrence of the feature values and the strength of these dependencies by rule support, confidence and lift analysis.