Captchas are used as a security mechanism on the web to distinguish human users from automated programs. However, existing captchas are not well-adapted to mobile devices and may lead users to abandon tasks. Although Web developers have many available captchas, they lack the tools to evaluate if these captchas are suitable for their mobile site. In this paper, we present domain specific usability heuristics for evaluating captchas on smartphones. To assess effectiveness, we compared our proposed heuristics against Nielsen's during evaluations of four captcha schemes on smartphones. The custom heuristics revealed more major problems and more detailed feedback on the problems than Nielsen's.

Additional Metadata
Keywords Captchas, Evaluation, HCI, Heuristic evaluation, HIPs, Smartphones
Persistent URL dx.doi.org/10.1145/2783446.2783583
Conference British HCI Conference, British HCI 2015
Citation
Reynaga, G. (Gerardo), Chiasson, S, & Van Oorschot, P. (2015). Heuristics for the evaluation of captchas on smartphones. In ACM International Conference Proceeding Series (pp. 126–135). doi:10.1145/2783446.2783583