Association rule mining for the usability of the CAPTCHA interfaces: a new study of multimedia systems

  • Darko Brodić
  • Alessia Amelio
Regular Paper


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.


CAPTCHA Multimedia interface Association rule mining Human–computer interaction Usability 

Mathematics Subject Classification

68Q10 91E10 97K40 97K80 97N80 97R40 97R99 



The authors are fully grateful to the anonymous users for publicly providing its data, and to Mr. Lucio Amelio, student of the Faculty of Medicine and Surgery, University of Bologna, Italy, for the helpful discussions about the biological effects of the human factors. This work was partially supported by the Grant of the Ministry of Education, Science and Technological Development of the Republic Serbia, as a part of the Project TR33037.

Compliance with ethical standards

Conflicts of interest

Author Darko Brodić declares that he has no conflict of interest. Author Alessia Amelio declares that she has no conflict of interest.

Ethical approval

This article does not contain any hazardous study involving human participants.


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Technical Faculty in BorUniversity of BelgradeBorSerbia
  2. 2.DIMESUniversity of CalabriaRendeItaly

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