  In this paper the elements of the CAPTCHA usability are analyzed. CAPTCHA, as
a time progressive element in computer science, has been under constant
interest of ordinary, professional as well as the scientific users of the
Internet. The analysis is given based on the usability elements of CAPTCHA
which are abbreviated as user-centric approach to the CAPTCHA. To demonstrate
it, the specific type of Dice CAPTCHA is used in the experiment. The experiment
is conducted on 190 Internet users with different demographic characteristics
on laptop and tablet computers. The obtained results are statistically
processed. At the end, the results are compared and conclusion of their use is
drawn.
